Vacuum pump apparatus

Abstract

A vacuum pump device is provided that can maintain the interior of the rotor chamber of the pump casing at a high temperature and allows for easy installation and removal of the heater. The vacuum pump device includes: a pump casing (2); a pump rotor (5) disposed in the rotor chamber (1); a rotating shaft (7) on which the pump rotor (5) is fixed; an electric motor (8) connected to the rotating shaft (7); side covers (10A, 10B) forming the end face (31a) of the rotor chamber (1); housing structures (14, 16) located axially on the side covers (10A, 10B) outside the side covers (10A, 10B); and a cylindrical heater (70A, 70B) disposed in the side covers (10A, 10B) and installed in a detachable manner, the cylindrical heater (70A, 70B) having a heater (71) and a heater shell (72) covering at least a portion of the heater (71), the heater shell (72) having a slit (72a) extending from one end of the heater shell to the other end.

Description

Technical Field

[0001] The present invention relates to a vacuum pump device, and more particularly to a vacuum pump device suitable for use in exhausting processing gases used in the manufacture of semiconductor devices, liquid crystals, LEDs, solar cells, and the like. Prior Art

[0002] In the manufacturing process of semiconductor devices, liquid crystal panels, LEDs, solar cells, etc., processing gases are introduced into a processing chamber to perform various processes such as etching and CVD. The processing gases introduced into the processing chamber are exhausted by a vacuum pump device. Generally, in these manufacturing processes that require high cleanliness, the vacuum pump device used 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 transfers gas by rotating a pair of pump rotors disposed in a rotor chamber in opposite directions.

[0003] There are cases where the processing gas contains by-products with a high sublimation temperature. When the temperature in the rotor chamber of the vacuum pump device is low, there are cases where the by-products solidify in the rotor chamber and accumulate on the inner surfaces of the pump rotor and the pump casing. The solidified by-products hinder the rotation of the pump rotor, causing a decrease in the speed of the pump rotor, and in the worst case, resulting in the stoppage of the operation of the vacuum pump device. Therefore, in order to prevent the solidification of the by-products, a heater is installed on the outer surface of the pump casing to heat the rotor chamber.

[0004] On the other hand, the motor that drives the pump rotor and the gears fixed to the rotating shaft of the pump rotor also need to be cooled. Therefore, the above-mentioned vacuum pump device generally includes a cooling system for cooling the motor and the gears. The cooling system is configured, for example, to cool the motor and the gears by circulating a coolant through cooling pipes provided in a motor housing that houses the motor and cooling pipes provided in a gear housing that houses the gears. With such a cooling system, it is possible to prevent overheating of the motor and the gears and achieve stable operation of the vacuum pump device. [Prior Art Documents] [Patent Documents]

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-35290 Patent Document 2: Japanese Patent Application Laid-Open No. 2021-63503 Summary of the Invention Problems to be Solved by the Invention

[0006] The heater installed in the pump housing is structured to be clamped by the side covers. Therefore, when replacing the heater due to its lifespan or the like, the vacuum pump device needs to be disassembled, and it is not easy to replace the heater.

[0007] Therefore, the present invention provides a vacuum pump device capable of maintaining the inside of the rotor chamber of the pump housing at a relatively high temperature and facilitating the loading and unloading of the heater. Means for Solving the Problem

[0008] In one aspect, a vacuum pump device is provided, including: a pump housing having a rotor chamber inside; a pump rotor disposed in the rotor chamber; a rotating shaft with the pump rotor fixed thereto; an electric motor connected to the rotating shaft; a side cover forming an end face of the rotor chamber; a housing structure located outside the side cover in the axial direction of the rotating shaft; and a cylindrical heater disposed inside the side cover or the pump housing and installed in a detachable manner. The cylindrical heater has a heater and a heater housing covering at least a part of the heater, and the heater housing has a slit extending from one end to the other end thereof.

[0009] In one aspect, the heater housing is made of a material having a higher linear expansion coefficient than the material of the outer housing of the heater. In one aspect, the heater housing is made of any one of aluminum alloy, aluminum, copper, and magnesium. In one aspect, the side cover or the pump housing has a hole that opens on the outer surface of the side cover or the pump housing and extends linearly, and the cylindrical heater has a rod-like outer shape and is disposed in the hole. In one aspect, the vacuum pump device further includes a fixing mechanism that fixes the cylindrical heater to the side cover or the pump housing in a detachable manner. Advantageous Effects of the Invention

[0010] According to the present invention, by installing the cylindrical heater inside the side cover or the pump housing, the inside of the rotor chamber can be maintained at a relatively high temperature. The slit formed in the heater housing can absorb the thermal expansion of the heater and the heater housing. Thereby, deformation of the cylindrical heater caused by deformation of the heater over time can be prevented, and the cylindrical heater can be easily removed from the side cover or the pump housing. The heater housing is made of a material with a higher coefficient of linear expansion than the material constituting the heater's outer shell, allowing it to fill the gap between the side cover or pump housing and the heater through thermal expansion. Therefore, heat can be efficiently transferred from the cylindrical heater to the side cover or pump housing. Simple Explanation of the Diagram

[0011] Figure 1 is a cross-sectional view showing one embodiment of the vacuum pump device. Figure 2 is a side view of the side cover according to the embodiment shown in Figure 1. Figure 3 is a cross-sectional view along line AA in Figure 2. Figure 4 is a three-dimensional view of a cylindrical heater. Figure 5 is a cross-sectional view of the BB line in Figure 4. Figure 6 is an enlarged cross-sectional view of the cylindrical heater inserted into the hole. Figure 7 is an enlarged cross-sectional view of the cylindrical heater during heating. Figure 8 is a cross-sectional view showing another embodiment of the vacuum pump device. Figure 9 is a cross-sectional view along line CC of Figure 8. Figure 10 is a cross-sectional view showing another embodiment of the vacuum pump device. Figure 11 is a side view of the side cover according to the embodiment shown in Figure 10. Figure 12 is a view taken from the direction indicated by arrow D in Figure 11. Figure 13 is a perspective view of the side cover shown in Figure 11. Implementation

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 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 Figure 1 is a so-called dry vacuum pump device that does not use oil in the gas flow path. Since the vaporized oil in the dry vacuum pump device does not flow upstream, it can be applied to manufacturing apparatuses for semiconductor devices that require high cleanliness.

[0013] As shown in Figure 1, the vacuum pump device includes: a pump casing 2 having a rotor chamber 1 inside; a pump rotor 5 disposed within the rotor chamber 1; a rotating shaft 7 fixed to the pump rotor; 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. Although only one pump rotor 5 and one rotating shaft 7 are depicted in Figure 1, a pair of pump rotors 5 are disposed within the rotor chamber 1 and respectively fixed to a pair of rotating shafts 7. The motor 8 is connected to one of the pair of rotating shafts 7. In one embodiment, the motor 8 may also be a pair of motors 8 each connected to a pair of rotating shafts 7.

[0014] The pump rotor 5 in this embodiment is a root-type pump rotor, but the type of 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 in this embodiment is a single-stage pump rotor, but in one embodiment, the pump rotor 5 may also be a multi-stage pump rotor.

[0015] The vacuum pump assembly also includes side covers 10A and 10B located on the outer side of the pump housing 2 along the axial direction of the rotating shaft 7. The side covers 10A and 10B are disposed 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 face of the pump housing 2 by screws (not shown).

[0016] 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 inlet 2a and an outlet 2b. The inlet 2a is connected to a chamber (not shown) filled with the gas to be transferred. In one example, the inlet 2a is connected to a processing chamber of a semiconductor device manufacturing apparatus, and the vacuum pump is used to exhaust the processing gas introduced into the processing chamber.

[0017] The vacuum pump assembly also includes, along the axial direction of the rotating shaft 7, a motor housing 14 and a gear housing 16, which are housing structures located outside the side covers 10A and 10B. 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.

[0018] The rotating shaft 7 is supported by bearing 17 held in side cover 10A and bearing 18 held in side cover 10B, enabling it to rotate. The motor housing 14 houses the motor rotor 8A and motor stator 8B of the motor 8. The motor housing 14 and gear housing 16 are examples of housing structures, but the housing structure is not limited to this embodiment. For example, the housing structure could also be a bearing housing that holds the bearings.

[0019] A pair of meshing gears 20 are arranged inside the gear housing 16. Furthermore, only one gear 20 is depicted in Figure 1. The electric motor 8 rotates via a motor driver (not shown), and the rotating shaft 7 of the side connected to the electric motor 8 rotates in the opposite direction via the gears 20 on the other side, which is not connected to the electric motor 8.

[0020] In one embodiment, a pair of electric motors 8 may be provided, each connected to a pair of rotating shafts 7. The pair of electric motors 8 rotate synchronously in opposite directions by a motor driver (not shown), and cause the pair of rotating shafts 7 and the pair of pump rotors 5 to rotate synchronously in opposite directions. In this case, the gear 20 serves to prevent inconsistencies in the synchronous rotation of the pump rotors 5 caused by sudden external factors.

[0021] When the pump rotor 5 rotates by the motor 8, gas is drawn into the pump casing 2 from the inlet 2a. The gas is then transferred from the inlet 2a to the outlet 2b by the rotating pump rotor 5.

[0022] A cooling flow path 21 is provided inside the motor housing 14. Similarly, a cooling flow path 22 is provided inside the gear housing 16. The cooling flow path 21 extends integrally into the peripheral wall of the motor housing 14, and the cooling flow path 22 extends integrally into the peripheral wall of the gear housing 16. Cooling flow paths 21 and 22 are connected to a coolant supply source (not shown). Coolant is supplied from the coolant supply source to the cooling flow paths 21 and 22. The coolant flowing in the cooling flow path 21 cools the motor housing 14, thereby cooling the motor 8 and bearing 17 disposed within the motor housing 14. The coolant flowing in the cooling flow path 22 cools the gear housing 16, thereby cooling the gear 20 and bearing 18 disposed within the gear housing 16.

[0023] The process gas handled by the vacuum pump device contains byproducts that solidify as the temperature decreases. During the operation of the vacuum pump device, the process gas is compressed as it is transferred from the inlet 2a to the outlet 2b by the pump rotor 5. Therefore, due to the heat of compression of the process gas, the interior of the rotor chamber 1 becomes high-temperature. The side cover 10A is configured to reduce heat transfer from the pump housing 2 to the motor housing 14, and the side cover 10B is configured to reduce heat transfer from the pump housing 2 to the gear housing 16. Therefore, the side covers 10A and 10B can maintain the high temperature inside the rotor chamber 1. In particular, the motor housing 14 and the gear housing 16 are cooled by the coolant flowing in the cooling channels 21 and 22, and the side covers 10A and 10B can maintain the high temperature inside the rotor chamber 1.

[0024] In this embodiment, the pump casing 2 and side covers 10A and 10B forming the rotor chamber 1 are made of cast iron. In one embodiment, the side covers 10A and 10B may also be made of a material with a lower thermal conductivity than cast iron.

[0025] The vacuum pump unit also includes cylindrical heaters 70A and 70B respectively disposed within side covers 10A and 10B. The cylindrical heaters 70A and 70B are detachably mounted on the side covers 10A and 10B. The structure of the cylindrical heaters 70A and 70B is described in detail below.

[0026] Since side covers 10A and 10B have essentially the same structure, and cylindrical heaters 70A and 70B have essentially the same structure, the side cover 10A and cylindrical heater 70A will be described below. Figure 2 is a side view of the side cover 10A according to the embodiment shown in Figure 1. Figure 3 is a cross-sectional view along line AA in Figure 2. The side cover 10A has a through hole 27 through which the rotating shaft 7 passes. The through hole 27 communicates with the rotor chamber 1.

[0027] The side cover 10A has: an inner wall portion 31 forming the end face 31a of the rotor chamber 1; an outer wall portion 32 located on the outer side of the inner wall portion 31 in the axial direction of the rotating shaft 7; and a plurality of partitions 34 sandwiched between the inner wall portion 31 and the outer wall portion 32. The inner wall portion 31 and the outer wall portion 32 are separated from each other by the partitions 34. The inner wall portion 31 is connected to the pump housing 2 (see Figure 1), and the outer wall portion 32 is connected to the motor housing 14. The outer wall portion 32 has a recess (not shown) for accommodating the bearing 17. A heat insulation member may also be arranged between the outer wall portion 32 and the motor housing 14.

[0028] The inner wall portion 31 of the side cover 10A has a hole 31b that opens onto the outer surface of the side cover 10A (more specifically, the outer surface of the inner wall portion 31). The hole 31b extends linearly. The cylindrical heater 70A has a linearly extending rod-shaped form and is disposed within the hole 31b. By providing the hole 31b at the location where the cylindrical heater 70A is to be installed, the vacuum pump device of this embodiment can partially install the cylindrical heater 70A.

[0029] In this embodiment, two cylindrical heaters 70A are arranged to clamp the rotating shaft 7 (see Figure 1). In one embodiment, only one cylindrical heater 70A may be provided, or more than three cylindrical heaters 70A may be provided. Although in this embodiment, the inner wall portion 31 and the outer wall portion 32 are separate, in one embodiment, the inner wall portion 31 and the outer wall portion 32 may be integrally formed without the separator 34. Moreover, in one embodiment, a hole 31b may be formed on the outer surface of the side cover of a conventional vacuum pump device, and the cylindrical heater 70A may be inserted into the hole 31b.

[0030] The cylindrical heater 70A is fixed to the side cover 10A by a screw 45, which serves as a fixing mechanism, while being inserted into the hole 31b. More specifically, the inner wall 31 of the side cover 10A has a screw hole 46 communicating with the hole 31b. When the screw 45 is screwed into the screw hole 46, the tip of the screw 45 presses the cylindrical heater 70A inside the hole 31b against the inner wall 31. Thus, the position of the cylindrical heater 70A is fixed. When the screw 45 is loosened, the cylindrical heater 70A can be removed from the hole 31b. Since the hole 31b is open on the outer surface of the side cover 10A, the cylindrical heater 70A can be removed from the side cover 10A without disassembling the vacuum pump device. Therefore, in the event of a malfunction of the cylindrical heater 70A, a new cylindrical heater can be easily replaced.

[0031] Next, the structure of the cylindrical heater 70A will be described. Figure 4 is a perspective view of the cylindrical heater 70A. Figure 5 is a cross-sectional view along line BB of Figure 4. The cylindrical heater 70A has a heater 71 and a heater housing 72 covering at least a portion of the heater 71. The heater 71 has a heating element 71a and a housing 71b surrounding the heating element 71a. The housing 71b is made of metal and functions to protect the heating element 71a and transfer the heat generated by the heating element 71a. The cylindrical heater 70A is a heating device in which the heater 71 is inserted inside the heater housing 722. Although the type of heater 71 is not particularly limited, a sheathed heater, which is a type of electric heater, can be used for the heater 71. The heater 71 is a linearly extending rod-shaped heater.

[0032] The heater housing 72 has openings at both ends and a cylindrical shape with a cylindrical space disposed inside. The heater housing 72 has a slit 72a extending from one end to the other. The slit 72a extends across the entire length of the heater housing 72. The cross-section of the heater housing 72 has an annular shape with the slit 72a opening having a width s1. In this embodiment, the total length of the heater housing 72 is the same as the total length of the heater 71, and the heater housing 72 covers the entire heater 71. In one embodiment, the total length of the heater housing 72 may also be longer than the total length of the heater 71.

[0033] Figure 6 is an enlarged cross-sectional view of the cylindrical heater 70A inserted into the hole 31b. As shown in Figure 6, before the heater 71 generates heat, the inner diameter of the hole 31b in the side cover 10A is... 1 ratio to the outer diameter of the heater housing 72 2. Therefore, with the cylindrical heater 70A inserted into the hole 31b, a gap is formed between the side cover 10A (more specifically, the inner wall constituting the hole 31b) and the heater housing 72. Before the heater 71 generates heat, the inner diameter of the heater housing 72... 3 ratio heater 71 outer diameter 4. Therefore, before the heater 71 generates heat, a gap is formed between the heater 71 and the heater housing 72.

[0034] In this embodiment, the outer casing 71b of the heater 71 is made of stainless steel. The coefficient of linear expansion of stainless steel is higher than that of cast iron, which constitutes the pump casing 2 and the side covers 10A and 10B. The heater casing 72 is made of a material with a higher coefficient of linear expansion than that of the outer casing 71b of the heater 71. More specifically, the heater casing 72 is made of a metal with a higher coefficient of linear expansion than that of the outer casing 71b of the heater 71. Examples of metals with a higher coefficient of linear expansion than the stainless steel constituting the outer casing 71b of the heater 71 include aluminum alloys, aluminum, copper, and magnesium.

[0035] When heat is generated from heater 71, the heat is transferred from side cover 10A to rotor chamber 1 (see Figure 1) via heater housing 72, thereby heating rotor chamber 1. As a result, the interior of rotor chamber 1 is maintained at a high temperature, thus preventing byproducts in the processed gas from solidifying.

[0036] Heater 71 can heat to approximately 600°C, and it undergoes thermal expansion. When heater 71 is repeatedly heated during long-term operation, it may deform. As a result, it becomes impossible to remove heater 71 from the side cover 10A, and it is difficult to easily replace heater 71 in case of failure. Considering the deformation of heater 71, the inner diameter of the hole 31b in the inner wall portion 31 is increased. At time 1, heat cannot be effectively transferred from heater 71 to side cover 10A. Therefore, the power consumption of heater 71 increases, and the operating cost increases.

[0037] Figure 7 is an enlarged cross-sectional view of the cylindrical heater 70A during heating. According to this embodiment, since the cylindrical heater 70A has a heater shell 72 covering the heater 71, when the heater 71 generates heat, the heater 71 and the heater shell 72 undergo thermal expansion. As a result, the gap between the heater 71 and the heater shell 72 becomes smaller. More specifically, the inner diameter of the heater shell 72... 3 and the outer diameter of heater 71 4. Equal. The heater housing 72 with slit 72a can absorb the deformation of the heater 71 over time. Therefore, it is possible to prevent the overall deformation of the cylindrical heater 70A caused by the deformation of the heater 71 over time, so that the cylindrical heater 70A can be easily removed from the side cover 10A.

[0038] The heater housing 72, made of a material with a higher coefficient of linear expansion than the outer shell 71b of the heater 71, expands more thermally than the heater 71. The heater housing 72 expands until it contacts the inner wall of the hole 31b forming the side cover 10A. More specifically, the outer diameter of the heater housing 72... 2 and the inner diameter of hole 31b 1. Equal. In this way, the thermally expanded heater shell 72 can fill the gap between the side cover 10A (more specifically, the inner wall forming the hole 31b) and the heater 71. Therefore, heat can be effectively transferred from the cylindrical heater 70A to the side cover 10A.

[0039] A comparison of Figures 6 and 7 shows that the thermal expansion of the heater housing 72 after contact with the hole 31b is absorbed by the slit 72a of the heater housing 72. More specifically, the thermal expansion of the heater housing 72 is limited by the hole 31b, while the heater housing 72 expands in the direction where the slit 72a narrows. As a result, the stress generated within the heater housing 72 is reduced, and deformation and damage to the heater housing 72 are prevented.

[0040] When the heater 71 stops heating and the temperature of the heater 71 and the heater housing 72 drops, the heater 71 and the heater housing 72 contract, creating a gap again between the side cover 10A (more specifically, the inner wall forming the hole 31b) and the heater housing 72. Therefore, the cylindrical heater 70A can be easily installed and removed from the side cover 10A.

[0041] Figure 8 is a cross-sectional view showing another embodiment of the vacuum pump device. Figure 9 is a cross-sectional view along line CC of Figure 8. Unless otherwise specified, the structure of this embodiment is the same as that described with reference to Figures 1 to 7, and therefore repeated descriptions are omitted. The cylindrical heater 70 of the vacuum pump device shown in Figure 8 is disposed within the pump housing 2. The cylindrical heater 70 is detachably mounted on the pump housing 2. The specific structure of the cylindrical heater 70 is the same as that of the cylindrical heater 70A described with reference to Figures 4 and 5.

[0042] A cylindrical heater 70 is disposed on both sides of the air inlet 2a and the air outlet 2b of the pump housing 2. As shown in FIG. 9, the pump housing 2 has a hole 2c opening on the outer surface of the pump housing 2. The hole 2c extends linearly. The cylindrical heater 70 has a linearly extending rod-shaped shape and is disposed within the hole 2c. In this embodiment, the vacuum pump device can partially install the cylindrical heater 70 by providing the hole 2c at the location where the cylindrical heater 70 is to be installed. In this embodiment, four cylindrical heaters 70 are arranged to clamp the air inlet 2a and the air outlet 2b of the pump housing 2. In one embodiment, three or fewer or five or more cylindrical heaters 70 may also be provided.

[0043] The cylindrical heater 70, when inserted into the hole 2c, is fixed to the pump housing 2 by a screw 45, which serves as a fixing mechanism. More specifically, the pump housing 2 has a screw hole 46 communicating with the hole 2c. When the screw 45 is screwed into the screw hole 46, the tip of the screw 45 presses the cylindrical heater 70 inside the hole 2c against the pump housing 2. Thus, the position of the cylindrical heater 70 is fixed. When the screw 45 is loosened, the cylindrical heater 70 can be removed from the hole 2c. Since the hole 2c is an opening on the outer surface of the pump housing 2, the cylindrical heater 70 can be removed from the pump housing 2 without disassembling the vacuum pump assembly. Therefore, in the event of a malfunction of the cylindrical heater 70, a new cylindrical heater can be easily replaced.

[0044] Since the inner diameter of the hole 2c of the pump housing 2, the outer and inner diameters of the heater housing 72 of the cylindrical heater 70, and the outer diameter of the heater 71 are related to the inner diameter of the hole 31b of the side cover 10A as described with reference to Figures 6 and 7, 1. The outer diameter of the heater shell 72 of the cylindrical heater 70A 2 and inner diameter 3 and the outer diameter of heater 71 The relationship in section 4 is the same, so its repeated explanation is omitted.

[0045] When heat is generated from heater 71, the heat is transferred from pump housing 2 to rotor chamber 1 (see Figure 8) via heater housing 72, thereby heating rotor chamber 1. As a result, the interior of rotor chamber 1 is maintained at a high temperature, thus preventing byproducts in the processed gas from solidifying.

[0046] According to this embodiment, since the cylindrical heater 70 has a heater housing 72 covering the heater 71, the heater 71 and the heater housing 72 undergo thermal expansion when the heater 71 generates heat. As a result, the gap between the heater 71 and the heater housing 72 becomes smaller. More specifically, the inner diameter of the heater housing 72 is equal to the outer diameter of the heater 71. The heater housing 72, having a slit 72a, can absorb the deformation of the heater 71 over time. Therefore, it is possible to prevent overall deformation of the cylindrical heater 70 caused by the deformation of the heater 71 over time, thereby allowing the cylindrical heater 70 to be easily removed from the pump housing 2.

[0047] The heater shell 72, made of a material with a higher coefficient of linear expansion than the outer shell 71b of the heater 71, expands more thermally than the heater 71. The heater shell 72 expands until it contacts the inner wall of the hole 2c that forms the pump housing 2. More specifically, the outer diameter of the heater shell 72 is equal to the inner diameter of the hole 2c. In this way, the thermally expanded heater shell 72 can fill the gap between the pump housing 2 (more specifically, the inner wall forming the hole 2c) and the heater 71. Therefore, heat can be effectively transferred from the cylindrical heater 70 to the pump housing 2.

[0048] When the heating of heater 71 stops and the temperature of heater 71 and heater housing 72 drops, heater 71 and heater housing 72 contract, and a gap is formed again between pump housing 2 (more specifically, the inner wall constituting orifice 2c) and heater housing 72. Therefore, the cylindrical heater 70 can be easily installed and removed from pump housing 2.

[0049] In one embodiment, in addition to the cylindrical heater 70 inside the pump housing 2 described above, the vacuum pump device may also further include cylindrical heaters 70A and 70B inside the side covers 10A and 10B, similar to the embodiments described with reference to Figures 1 to 7.

[0050] Figure 10 is a cross-sectional view showing another embodiment of the vacuum pump device. Figure 11 is a side view of the side cover involved in the embodiment shown in Figure 10. Figure 12 is a view taken from the direction indicated by arrow D in Figure 11. Figure 13 is a perspective view of the side cover 10A shown in Figure 11. The structure of this embodiment, unless otherwise described, is the same as that of the embodiments described with reference to Figures 1 to 7, and therefore repeated descriptions are omitted. The side covers 10A and 10B of the vacuum pump device shown in Figure 10 also include a reduced diameter portion 33 and a heater housing 35. The cylindrical heaters 70A and 70B are detachably mounted on the heater housings 35 of the side covers 10A and 10B, respectively. The specific structures of the cylindrical heaters 70A and 70B are the same as those of the cylindrical heater 70A described with reference to Figures 4 and 5.

[0051] The side cover 10A of this embodiment has: an inner wall portion 31 forming the end face 31a of the rotor chamber 1; an outer wall portion 32 located on the outer side relative to the inner wall portion 31 in the axial direction of the rotating shaft 7; and a reduced diameter portion 33 located between the inner wall portion 31 and the outer wall portion 32. The inner wall portion 31 is connected to the pump housing 2, and the outer wall portion 32 is connected to the motor housing 14. The outer wall portion 32 has a recess 32a for accommodating the bearing 17. A heat insulation member may also be provided between the outer wall portion 32 and the motor housing 14.

[0052] The inner sidewall portion 31, the outer sidewall portion 32, and the reduced diameter portion 33 are integrally formed. In this embodiment, the inner sidewall portion 31, the outer sidewall portion 32, and the reduced diameter portion 33 are integrally cast parts. Since the side cover 10A is thus an integrally formed part, it is not necessary to separately manufacture multiple parts and assemble them. As a result, manufacturing costs can be reduced.

[0053] The reduced diameter portion 33 has a shorter outer circumference than the inner wall portion 31 and the outer wall portion 32. That is, the reduced diameter portion 33 has a smaller cross-sectional area than the inner wall portion 31 and the outer wall portion 32. Although the inner wall portion 31, the outer wall portion 32, and the reduced diameter portion 33 are made of the same material, because the cross-sectional area of ​​the reduced diameter portion 33 is smaller than that of the inner wall portion 31 and the outer wall portion 32, it is difficult to transfer heat from the inner wall portion 31 to the outer wall portion 32 through the reduced diameter portion 33. Although the description is omitted, the side cover 10B also has essentially the same structure. Because the side covers 10A and 10B with such a reduced diameter portion 33 have high thermal insulation performance, the rotor chamber 1 can be maintained at a high temperature. Furthermore, it is possible to prevent the coolant flowing in the cooling flow path 21 and the cooling flow path 22 from cooling the pump casing 2.

[0054] The side cover 10A has two heater housings 35, each having a hole 35a. The two heater housings 35, the inner sidewall portion 31, the outer sidewall portion 32, and the reduced diameter portion 33 are integrally formed. Each hole 35a opens on the outer surface of the side cover 10A (more specifically, the outer surface of the heater housing 35), and a cylindrical heater 70A is disposed within the hole 35a. In this embodiment, the two cylindrical heaters 70A are arranged to clamp the rotating shaft 7. In one embodiment, only one cylindrical heater 70A may be provided, or three or more cylindrical heaters 70A may be provided.

[0055] The hole 35a extends linearly, and the cylindrical heater 70A is also a linearly extending rod-shaped heater. The cylindrical heater 70A, when inserted into the hole 35a, is fixed to the side cover 10A by a screw 45, which serves as a fixing mechanism. More specifically, the heater housing 35 has a screw hole 46 communicating with the hole 35a. When the screw 45 is screwed into the screw hole 46, the tip of the screw 45 presses the cylindrical heater 70A inside the hole 35a against the heater housing 35. Thus, the position of the cylindrical heater 70A is fixed. When the screw 45 is loosened, the cylindrical heater 70A can be removed from the hole 35a. Since the hole 35a is open on the outer surface of the side cover 10A, the cylindrical heater 70A can be removed from the side cover 10A without disassembling the vacuum pump unit. Therefore, in the event of a malfunction of the cylindrical heater 70A, a new cylindrical heater can be easily replaced.

[0056] Since the inner diameter of the hole 35a of the heater housing 35 in this embodiment, the outer and inner diameters of the heater housing 72 of the cylindrical heater 70A, and the outer diameter of the heater 71 are related to the inner diameter of the hole 31b of the side cover 10A as described with reference to Figures 6 and 7... 1. The outer diameter of the heater shell 72 of the cylindrical heater 70A 2 and inner diameter 3 and the outer diameter of heater 71 The relationship in section 4 is the same, so its repeated explanation is omitted.

[0057] When heat is generated from heater 71, the heat is transferred from heater housing 35 and inner wall portion 31 to rotor chamber 1 (see Figure 10) via heater housing 72, thereby heating rotor chamber 1. This maintains the interior of rotor chamber 1 at a high temperature, preventing the solidification of byproducts in the processed gas. In particular, since heater housing 35 and inner wall portion 31 are integrally formed, the heat transfer efficiency from cylindrical heater 70A to inner wall portion 31 is improved.

[0058] As shown in Figure 13, at least a portion of the heater housing 35 is separated from the outer wall portion 32. Although not shown, the entire heater housing 35 may also be separated from the outer wall portion 32. With this structure, heat generated from the heater 71 and transferred through the heater housing 72 is difficult to transfer to the outer wall portion 32. Therefore, the cylindrical heater 70A can heat the rotor chamber 1 and prevent heating of the motor housing 14 (see Figure 10), which is a housing structure connected to the outer wall portion 32.

[0059] According to this embodiment, since the cylindrical heater 70A has a heater housing 72 covering the heater 71, the heater 71 and the heater housing 72 undergo thermal expansion when the heater 71 generates heat. As a result, the gap between the heater 71 and the heater housing 72 becomes smaller. More specifically, the inner diameter of the heater housing 72 is equal to the outer diameter of the heater 71. The heater housing 72, having a slit 72a, can absorb the deformation of the heater 71 over time. Therefore, it is possible to prevent overall deformation of the cylindrical heater 70A caused by the deformation of the heater 71 over time, thereby allowing the cylindrical heater 70A to be easily removed from the heater housing 35.

[0060] The heater shell 72, made of a material with a higher coefficient of linear expansion than the outer shell 71b of the heater 71, expands more thermally than the heater 71. The heater shell 72 expands until it contacts the inner wall of the hole 35a forming the heater housing 35. More specifically, the outer diameter of the heater shell 72 is equal to the inner diameter of the hole 35a. In this way, the thermally expanded heater shell 72 can fill the gap between the heater housing 35 (more specifically, the inner wall forming the hole 35a) and the heater 71. Therefore, heat can be effectively transferred from the cylindrical heater 70A to the heater housing 35.

[0061] When the heater 71 stops heating and the temperature of the heater 71 and the heater housing 72 drops, the heater 71 and the heater housing 72 contract, and a gap is formed again between the heater housing 35 (more specifically, the inner wall forming the hole 35a) and the heater housing 72. Therefore, the cylindrical heater 70A can be easily installed and removed from the heater housing 35.

[0062] As shown in Figure 10, a cylindrical heater 70B is also disposed inside the side cover 10B. Since the descriptions with reference to Figures 11 to 13 also apply to the side cover 10B and the cylindrical heater 70B disposed inside the side cover 10B, these repeated descriptions are omitted.

[0063] In one embodiment, in addition to the cylindrical heaters 70A and 70B inside the side covers 10A and 10B as described above, the vacuum pump device may also further include a cylindrical heater 70 inside the pump housing 2, similar to the embodiment described with reference to FIG8 and FIG9.

[0064] The above embodiments are described with the aim of enabling those skilled in the art to implement the present invention. Various modifications of the above embodiments can naturally be implemented by 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, and the technical concept is interpreted in the broadest sense according to the scope of the claims.

[0065] 1: Rotor chamber 2: Pump casing 2a: Air intake 2b: Exhaust port 2c: Hole 5: Pump rotor 7: Rotation axis 8: Electric motor 8A: Motor rotor 8B: Motor stator 10A, 10B: Side shields 14: Motor housing (housing structure) 16: Gear housing (housing structure) 17, 18: Bearings 20: Gear 21,22: Cooling flow path 27: Through hole 31: Inner wall portion 31a: End face 31b: Hole 32: Outer wall portion 32a: Recessed portion 33: Reduction section 34: Separator 35: Heater housing 35a: Hole 45: Screw 46: Screw hole 70, 70A, 70B: Cylindrical heaters 71: Heater 71a: Heating element 71b: Outer shell 72: Heater housing 72a: Slit

Claims

1. A vacuum pump device comprising: a pump housing having a rotor chamber inside; a pump rotor disposed within the rotor chamber; a rotating shaft to which the pump rotor is fixed; an electric motor connected to the rotating shaft; a side cover forming an end face of the rotor chamber; a housing structure located axially outside the side cover of the rotating shaft; and a cylindrical heater disposed within the side cover or the pump housing and detachably mounted, the cylindrical heater having a heater and a heater housing covering at least a portion of the heater, the heater housing having a slit extending from one end to the other, and the heater housing being made of a material having a coefficient of linear expansion higher than that of the material constituting the outer shell of the heater.

2. The vacuum pump apparatus as claimed in claim 1, wherein, The aforementioned heater housing is made of any one of aluminum alloy, aluminum, copper, and magnesium.

3. The vacuum pump apparatus as claimed in claim 1 or 2, wherein, The aforementioned side cover or the aforementioned pump housing has a hole that opens on the outer surface of the side cover or the pump housing and extends in a straight line. The aforementioned cylindrical heater has a rod-shaped shape and is disposed within the aforementioned hole.

4. The vacuum pump device as claimed in claim 1 or 2, further comprising a fixing mechanism that secures the aforementioned cylindrical heater to the aforementioned side cover or the aforementioned pump housing in a detachable manner.

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