EP4656883A1

EP4656883A1 - Vacuum pump

Info

Publication number: EP4656883A1
Application number: EP24747274.9A
Authority: EP
Inventors: Kentaro Sato; Tooru Miwata; Shigeyoshi Nakatsuji
Original assignee: Edwards Japan Ltd
Current assignee: Edwards Japan Ltd
Priority date: 2023-01-24
Filing date: 2024-01-23
Publication date: 2025-12-03
Also published as: JP7598396B2; TW202436764A; CN120569568A; KR20250135869A; WO2024157947A1; JP2024104364A

Abstract

A vacuum pump capable of further improving safety is provided. A turbomolecular pump 100 includes: a casing 215 including at least an outlet port 133 from among an inlet port 101 and the outlet port 133; a heater 148 configured to cause a portion of at least the casing 215 to have a high temperature from among the casing 215 and the outlet port 133. The turbomolecular pump 100 includes a side surface cover 224 that covers the side surface of the casing 215, the side surface cover having an annular shape and a thin plate shape, and an outlet port cover 222 that covers a surrounding of the outlet port 133, the outlet port cover having a thin plate shape. The outlet port cover 222 and the side surface cover 224 are separate components and is attachable and detachable, with the side surface cover 224 being attached.

Description

The present invention relates to a vacuum pump such as a turbomolecular pump.
Turbomolecular pumps are commonly known as one type of vacuum pumps. In a turbomolecular pump, a motor in a pump main body is energized to rotate rotor blades, which hit gaseous molecules (gas molecules) of gas (process gas) drawn into the pump main body, thereby exhausting the gas. Some types of such turbomolecular pumps have heaters and cooling pipes to appropriately control a temperature inside the pumps.
PTL 1 described below indicates that a cover member covers a base through an air insulating layer and that a risk of a user coming into contact with a high temperature portion is avoided (paragraphs 0005 and 0006, for example).
[PTL 1] Japanese Patent Application Publication No. 2022-158145
PTL 1 (paragraph 0029, for example) indicates that the cover member covers an outer circumference of a base to avoid a risk of a user coming into contact with the base, which is a high temperature portion, and that heat is not transmitted to the cover member, and moreover that the cover member is cooled, for example. However, further improvements are needed to further improve the safety of vacuum pumps.
It is an object of the present invention to provide a vacuum pump capable of further improving safety.
A vacuum pump according to the present invention for achieving the above object includes:

a casing including at least an outlet port from among an inlet port and the outlet port; and
a heating means for causing a portion of at least the casing to have a high temperature, from among the casing and the outlet port, wherein
the vacuum pump includes:
- a side surface cover that covers a side surface of the casing, the side surface cover having an annular shape and a thin plate shape; and
- an outlet port cover that covers a surrounding of the outlet port, the outlet port cover having a thin plate shape, and
- the outlet port cover is a member separate from the side surface cover and is attachable and detachable, with the side surface cover being attached.

According to the above invention, it is possible to provide a vacuum pump capable of further improving safety.

[Fig. 1]
Fig. 1 is an explanatory diagram schematically showing the configuration of a turbomolecular pump according to an embodiment of the present invention.
[Fig. 2]
Fig. 2 is a circuit diagram of an amplifier circuit.
[Fig. 3]
Fig. 3 is a time chart showing control performed when a current command value is greater than a detected value.
[Fig. 4]
Fig. 4 is a time chart showing control performed when a current command value is less than a detected value.
[Fig. 5]
Fig. 5 is an explanatory diagram showing the configuration of the same turbomolecular pump as in Fig. 1 with different parts assigned with reference numerals.
[Fig. 6]
Fig. 6 is a side view showing the side of the turbomolecular pump including an exhaust port 15.
[Fig. 7]
Fig. 7 is a side view showing the turbomolecular pump with the side including the exhaust port 15 located on the rear side.
[Fig. 8]
Fig. 8 is a side view of the turbomolecular pump of Fig. 6 with a second outlet port cover component 222B and a second side surface cover component 224B removed.
[Fig. 9]
Fig. 9 is a side view of the turbomolecular pump of Fig. 7 with the second side surface cover component 224B removed.
[Fig. 10]
Fig. 10(a) is a perspective view showing the second outlet port cover component 222B, and Fig. 10(b) is a perspective view showing the second side surface cover component 224B.
[Fig. 11]
Fig. 11 is an explanatory diagram schematically showing the configuration of a turbomolecular pump of a modification.

Referring to the drawings, a vacuum pump according to a first embodiment of the present invention is now described. Fig. 1 shows a turbomolecular pump 100 as a vacuum pump according to the first embodiment of the present invention. The turbomolecular pump 100 is to be connected to a vacuum chamber (not shown) of a target apparatus such as a semiconductor manufacturing apparatus.

<<Basic Configuration of Turbomolecular Pump 100>>

Fig. 1 is a vertical cross-sectional view of the turbomolecular pump 100. As shown in Fig. 1, the turbomolecular pump 100 has a circular outer cylinder 127 having an inlet port 101 at its upper end. A rotating body 103 in the outer cylinder 127 includes a plurality of rotor blades 102 (102a, 102b, 102c, ...), which are turbine blades for gas suction and exhaustion, in its outer circumference section. The rotor blades 102 extend radially in multiple stages. The rotating body 103 has a rotor shaft 113 in its center. The rotor shaft 113 is supported and suspended in the air and position-controlled by a magnetic bearing of 5-axis control, for example.
Upper radial electromagnets 104 include four electromagnets arranged in pairs on an X-axis and a Y-axis. Four upper radial sensors 107 are provided in close proximity to the upper radial electromagnets 104 and associated with the respective upper radial electromagnets 104. Each upper radial sensor 107 may be an inductance sensor or an eddy current sensor having a conduction winding, for example, and detects the position of the rotor shaft 113 based on a change in the inductance of the conduction winding, which changes according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect a radial displacement of the rotor shaft 113, that is, the rotating body 103 fixed to the rotor shaft 113, and send it to the controller 200 indicated by a dashed line.
In the controller 200, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnets 104 based on a position signal detected by the upper radial sensors 107. Based on this excitation control command signal, an amplifier circuit 150 (described below) shown in Fig. 2 controls and excites the upper radial electromagnets 104 to adjust a radial position of an upper part of the rotor shaft 113.
The rotor shaft 113 may be made of a high magnetic permeability material (such as iron and stainless steel) and is configured to be attracted by magnetic forces of the upper radial electromagnets 104. The adjustment is performed independently in the X-axis direction and the Y-axis direction. Lower radial electromagnets 105 and lower radial sensors 108 are arranged in a similar manner as the upper radial electromagnets 104 and the upper radial sensors 107 to adjust the radial position of the lower part of the rotor shaft 113 in a similar manner as the radial position of the upper part.
Additionally, axial electromagnets 106A and 106B are arranged so as to vertically sandwich a metal disc 111 (also referred to as an "armature disc"), which has the shape of a circular disc and is provided in the lower part of the rotor shaft 113. The metal disc 111 is made of a high magnetic permeability material such as iron. An axial sensor 109 is provided to detect an axial displacement of the rotor shaft 113 and send an axial position signal to the controller 200.
In the controller 200, the compensation circuit having the PID adjustment function may generate an excitation control command signal for each of the axial electromagnets 106A and 106B based on the signal on the axial position detected by the axial sensor 109. Based on these excitation control command signals, the amplifier circuit 150 controls and excites the axial electromagnets 106A and 106B separately so that the axial electromagnet 106A magnetically attracts the metal disc 111 upward and the axial electromagnet 106B attracts the metal disc 111 downward. The axial position of the rotor shaft 113 is thus adjusted.
As described above, the controller 200 appropriately adjusts the magnetic forces exerted by the axial electromagnets 106A and 106B on the metal disc 111, magnetically levitates the rotor shaft 113 in the axial direction, and suspends the rotor shaft 113 in the air in a non-contact manner. The amplifier circuit 150, which controls and excites the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B, is described below.
The motor 121 includes a plurality of magnetic poles circumferentially arranged to surround the rotor shaft 113. Each magnetic pole is controlled by the controller 200 so as to drive and rotate the rotor shaft 113 via an electromagnetic force acting between the magnetic pole and the rotor shaft 113. The motor 121 also includes a rotational speed sensor (not shown), such as a Hall element, a resolver, or an encoder, and the rotational speed of the rotor shaft 113 is detected based on a detection signal of the rotational speed sensor.
Furthermore, a phase sensor (not shown) is attached adjacent to the lower radial sensors 108 to detect the phase of rotation of the rotor shaft 113. The controller 200 detects the position of the magnetic poles using both detection signals of the phase sensor and the rotational speed sensor.
A plurality of stator blades 123 (123a, 123b, 123c, ...) are arranged slightly spaced apart (by predetermined gaps) from the rotor blades 102 (102a, 102b, 102c). Each rotor blade 102 (102a, 102b, 102c, ...) is inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transfer exhaust gas molecules downward through collision.
The stator blades 123 are also inclined by a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113. The stator blades 123 extend inward of the outer cylinder 127 and alternate with the stages of the rotor blades 102. The outer circumference ends of the stator blades 123 are inserted between and thus supported by a plurality of layered stator blade spacers 125 (125a, 125b, 125c, ...).
The stator blade spacers 125 are ring-shaped members made of a metal, such as aluminum, iron, stainless steel, or copper, or an alloy containing these metals as components, for example. The outer cylinder 127 is fixed to the outer circumferences of the stator blade spacers 125 with a slight gap. A base portion 129 is located at the base of the outer cylinder 127. The base portion 129 has an outlet port 133 providing communication to the outside. The exhaust gas transferred to the base portion 129 through the inlet port 101 from the chamber (vacuum chamber) is then sent to the outlet port 133.
According to the application of the turbomolecular pump 100, a threaded spacer 131 may be provided between the lower part of the stator blade spacer 125 and the base portion 129. The threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, or iron, or an alloy containing these metals as components. The threaded spacer 131 has a plurality of helical thread grooves (not shown) in its inner circumference surface. When exhaust gas molecules move in the rotation direction of the rotating body 103, these molecules are transferred toward the outlet port 133 in the direction of the helix of the thread grooves (not shown). A rotating body lower cylindrical portion 103b extends downward from the lower part of a rotating body main portion 103a of the rotating body 103 including the rotor blades 102 (102a, 102b, 102c, ...). The outer circumference surface of the rotating body lower cylindrical portion 103b is cylindrical and projects toward the inner circumference surface of the threaded spacer 131. The outer circumference surface is adjacent to but separated from the inner circumference surface of the threaded spacer 131 by a predetermined gap. The exhaust gas transferred to the thread groove (not shown) by the rotor blades 102 and the stator blades 123 is guided by the thread groove (not shown) to the base portion 129. Thus, the threaded spacer 131 and the opposed rotating body lower cylindrical portion 103b form a Holweck type exhaust mechanism portion. The Holweck type exhaust mechanism portion gives directivity to the exhaust gas by rotating the rotating body lower cylindrical portion 103b relative to the threaded spacer 131, thereby improving the exhaust characteristics of the turbomolecular pump 100.
The base portion 129 is a disc-shaped member forming the base section of the turbomolecular pump 100, and is generally made of a metal such as iron, aluminum, or stainless steel. The base portion 129 physically holds the turbomolecular pump 100 and also serves as a heat conduction path. As such, the base portion 129 is preferably made of rigid metal with high thermal conductivity, such as iron, aluminum, or copper.
In this configuration, when the motor 121 drives and rotates the rotor blades 102 together with the rotor shaft 113, the interaction between the rotor blades 102 and the stator blades 123 causes the suction of exhaust gas from the chamber through the inlet port 101. The exhaust gas taken through the inlet port 101 moves between the rotor blades 102 and the stator blades 123 and is transferred to the base portion 129. At this time, factors such as the friction heat generated when the exhaust gas comes into contact with the rotor blades 102 and the conduction of heat generated by the motor 121 increase the temperature of the rotor blades 102. This heat is conducted to the stator blades 123 through radiation or conduction via gaseous molecules (gas molecules) of the exhaust gas, for example.
The stator blade spacers 125 are joined to each other at the outer circumference portion and conduct the heat received by the stator blades 123 from the rotor blades 102, the friction heat generated when the exhaust gas comes into contact with the stator blades 123, and the like to the outside.
In the above description, the threaded spacer 131 is provided at the outer circumference of the rotating body lower cylindrical portion 103b of the rotating body 103, and the thread groove (not shown) is engraved in the inner circumference surface of the threaded spacer 131. However, this may be inversed in some cases, and a thread groove may be engraved in the outer circumference surface of the rotating body lower cylindrical portion 103b, while a spacer having a cylindrical inner circumference surface may be arranged around the outer circumference surface.
According to the application of the turbomolecular pump 100, to prevent the gas drawn through the inlet port 101 from entering an electrical portion, which includes the upper radial electromagnets 104, the upper radial sensors 107, the motor 121, the lower radial electromagnets 105, the lower radial sensors 108, the axial electromagnets 106A, 106B, and the axial sensor 109, the electrical portion may be surrounded by a stator column 122. The inside of the stator column 122 may be maintained at a predetermined pressure by purge gas (protection gas).
In this case, the base portion 129 has a purge gas introduction pipe (not shown, also referred to as a "purge gas port") through which the purge gas is introduced. The introduced purge gas is sent to the outlet port 133 through gaps between a protective bearing 120 and the rotor shaft 113, between the rotor and the stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102 (the rotating body lower cylindrical portion 103b) and the base portion 129.
The turbomolecular pump 100 requires the identification of the model and control based on individually adjusted unique parameters (for example, various characteristics associated with the model). To store these control parameters, the turbomolecular pump 100 includes an electronic circuit portion 141 in its main body. The electronic circuit portion 141 may include a semiconductor memory, such as an EEPROM, electronic components such as semiconductor elements for accessing the semiconductor memory, and a substrate 143 for mounting these components. The electronic circuit portion 141 is housed under a rotational speed sensor (not shown) near the center, for example, of the base portion 129, which forms the lower part of the turbomolecular pump 100, and is closed by an airtight bottom lid 145.
Some process gas introduced into the chamber in the manufacturing process of semiconductors has the property of becoming solid when its pressure becomes higher than a predetermined value or its temperature becomes lower than a predetermined value. In the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the inlet port 101 and highest at the outlet port 133. When the pressure of the process gas increases beyond a predetermined value or its temperature decreases below a predetermined value while the process gas is being transferred from the inlet port 101 to the outlet port 133, the process gas is solidified and adheres and accumulates on the inner side of the turbomolecular pump 100.
For example, when SiCl4 is used as the process gas in an Al etching apparatus, according to the vapor pressure curve, a solid product (for example, AlCl3) is deposited at a low vacuum (760 [torr] to 10-2 [torr]) and a low temperature (about 20 [°C]) and adheres and accumulates on the inner side of the turbomolecular pump 100. When the deposit of the process gas accumulates in the turbomolecular pump 100, the accumulation may narrow the pump flow passage and degrade the performance of the turbomolecular pump 100. The above-mentioned product tends to solidify and adhere in areas with higher pressures, such as the vicinity of the outlet port 133 and the vicinity of the threaded spacer 131.
To solve this problem, conventionally, a heater or annular water-cooled tube 149 (not shown) is wound around the outer circumference of the base portion 129, and a temperature sensor (e.g., a thermistor, not shown) is embedded in the base portion 129, for example. The signal of this temperature sensor is used to perform control to maintain the temperature of the base portion 129 at a constant high temperature (preset temperature) by heating with the heater or cooling with the water-cooled tube 149 (hereinafter referred to as TMS (temperature management system)). In the present embodiment, a heater (not shown) embedded in the threaded spacer 131 heats the threaded spacer 131, and the water-cooled tube 149 embedded in the bottom lid 145 cools the base portion 129.
The amplifier circuit 150 is now described that controls and excites the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B of the turbomolecular pump 100 configured as described above. Fig. 2 is a circuit diagram of the amplifier circuit.
In Fig. 2, one end of an electromagnet winding 151 forming an upper radial electromagnet 104 or the like is connected to a positive electrode 171a of a power supply 171 via a transistor 161, and the other end is connected to a negative electrode 171b of the power supply 171 via a current detection circuit 181 and a transistor 162. Each transistor 161, 162 is a power MOSFET and has a structure in which a diode is connected between the source and the drain thereof.
In the transistor 161, a cathode terminal 161a of its diode is connected to the positive electrode 171a, and an anode terminal 161b is connected to one end of the electromagnet winding 151. In the transistor 162, a cathode terminal 162a of its diode is connected to a current detection circuit 181, and an anode terminal 162b is connected to the negative electrode 171b.
A diode 165 for current regeneration has a cathode terminal 165a connected to one end of the electromagnet winding 151 and an anode terminal 165b connected to the negative electrode 171b. Similarly, a diode 166 for current regeneration has a cathode terminal 166a connected to the positive electrode 171a and an anode terminal 166b connected to the other end of the electromagnet winding 151 via the current detection circuit 181. The current detection circuit 181 may include a Hall current sensor or an electric resistance element, for example.
The amplifier circuit 150 configured as described above corresponds to one electromagnet. Accordingly, when the magnetic bearing uses 5-axis control and has ten electromagnets 104, 105, 106A, and 106B in total, an identical amplifier circuit 150 is configured for each of the electromagnets. These ten amplifier circuits 150 are connected to the power supply 171 in parallel.
An amplifier control circuit 191 may be formed by a digital signal processor portion (not shown, hereinafter referred to as a DSP portion) of the controller 200. The amplifier control circuit 191 switches the transistors 161 and 162 between on and off.
The amplifier control circuit 191 is configured to compare a current value detected by the current detection circuit 181 (a signal reflecting this current value is referred to as a current detection signal 191c) with a predetermined current command value. The result of this comparison is used to determine the magnitude of the pulse width (pulse width time Tp1, Tp2) generated in a control cycle Ts, which is one cycle in PWM control. As a result, gate drive signals 191a and 191b having this pulse width are output from the amplifier control circuit 191 to gate terminals of the transistors 161 and 162.
Under certain circumstances such as when the rotational speed of the rotating body 103 reaches a resonance point during acceleration, or when a disturbance occurs during a constant speed operation, the rotating body 103 may require positional control at high speed and with a strong force. For this purpose, a high voltage of about 50 V, for example, is used for the power supply 171 to enable a rapid increase (or decrease) in the current flowing through the electromagnet winding 151. Additionally, a capacitor is generally connected between the positive electrode 171a and the negative electrode 171b of the power supply 171 to stabilize the power supply 171 (not shown).
In this configuration, when both transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereinafter referred to as an electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.
Also, when one of the transistors 161 and 162 is turned on and the other is turned off, a freewheeling current is maintained. Passing the freewheeling current through the amplifier circuit 150 in this manner reduces the hysteresis loss in the amplifier circuit 150, thereby limiting the power consumption of the entire circuit to a low level. Moreover, by controlling the transistors 161 and 162 as described above, high frequency noise, such as harmonics, generated in the turbomolecular pump 100 can be reduced. Furthermore, by measuring this freewheeling current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.
That is, when the detected current value is smaller than the current command value, as shown in Fig. 3, the transistors 161 and 162 are simultaneously on only once in the control cycle Ts (for example, 100 µs) for the time corresponding to the pulse width time Tp1. During this time, the electromagnet current iL increases accordingly toward the current value iLmax (not shown) that can be passed from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.
When the detected current value is larger than the current command value, as shown in Fig. 4, the transistors 161 and 162 are simultaneously off only once in the control cycle Ts for the time corresponding to the pulse width time Tp2. During this time, the electromagnet current iL decreases accordingly toward the current value iLmin (not shown) that can be regenerated from the negative electrode 171b to the positive electrode 171a via the diodes 165 and 166.
In either case, after the pulse width time Tp1, Tp2 has elapsed, one of the transistors 161 and 162 is on. During this period, the freewheeling current is thus maintained in the amplifier circuit 150.
In the turbomolecular pump 100 with the basic configuration described above, the upper side as viewed in Fig. 1 (the side including the inlet port 101) serves as a suction portion connected to the target apparatus, and the lower side (the side including an exhaust port 15 forming the outlet port 133 and protruding rightward as viewed in the figure from the base portion 129) serves as an exhaust portion connected to an auxiliary pump (back pump) or the like (not shown). The turbomolecular pump 100 can be used not only in an upright position in the vertical direction shown in Fig. 1, but also in an inverted position, a horizontal position, and an inclined position.
In the turbomolecular pump 100, the above-mentioned outer cylinder 127, a heater spacer 212 described below, an outer wall 214 described below, the base portion 129, and the like are combined to form a casing 215. The casing 215 will be described below. The turbomolecular pump 100 of the example of Fig. 1 includes a circular box-shaped electrical case 198. The above-mentioned controller 200 is placed in the electrical case 198.
The configuration inside the casing 215 of the turbomolecular pump 100 may be divided into a rotation mechanism portion, which rotates the rotor shaft 113 and the like with the motor 121, and an exhaust mechanism portion, which is driven and rotated by the rotation mechanism portion. The exhaust mechanism portion may be divided into a turbomolecular pump mechanism portion, which may include the rotor blades 102, the stator blades 123, and the like, and a thread groove pump mechanism portion (Holweck type exhaust mechanism portion), which may include the rotating body lower cylindrical portion 103b, the threaded spacer 131, and the like.
The above-mentioned purge gas (protection gas) is used to protect components such as the bearing portions and the rotor blades 102, prevents corrosion caused by the exhaust gas (process gas), and cools the rotor blades 102, for example. This purge gas may be supplied by a general technique.
For example, a purge gas port (not shown) extending linearly in a radial direction may be provided in a predetermined section of the base portion 129 (for example, at a position approximately 180 degrees apart from the outlet port 133). The purge gas may be supplied to the purge gas port from the outside of the base portion 129 via a purge gas cylinder (e.g., N2 gas cylinder), a flow rate regulator (valve device), or the like.
The protective bearing 120 described above is also referred to as a "touchdown (T/D) bearing", a "backup bearing", or the like. In case of any trouble such as trouble in the electrical system or entry of air, the protective bearing 120 prevents a significant change in the position and orientation of the rotor shaft 113, thereby limiting damage to the rotor blades 102 and surrounding portions.
In Fig. 1 of the structure of the turbomolecular pump 100 and the rotating body 103, hatch patterns indicating cross sections of components other than the heater 148 are omitted to avoid complicating the drawing.

<<Configuration of Casing 215>>

As with Fig. 1, Fig. 5 shows the internal structure of the turbomolecular pump 100 of the present embodiment. In Fig. 1, details of the casing 215 and reference numerals relating to a heat insulating cover 210, which will be described below, are omitted to avoid complicating the drawing.
Fig. 5 shows details of the casing 215 and reference numerals for the heat insulating cover 210, which will be described below. Also, in Fig. 5, only some components (the heater 148, the outer wall 214, and a heat insulator washer 220) are hatched to clearly distinguish them from surrounding components.
The casing 215 partially has a double structure. The section of the casing 215 from a midpoint in the axial direction to the base portion 129 is constituted by a heater spacer 212 and the outer wall 214. Although details will be described below, the heater spacer 212 is a structure that retains a vacuum in the exhaust flow passage in the turbomolecular pump 100, and constitutes an inner casing. The outer wall 214 is a structure that covers the surrounding of the heater spacer 212 and constitutes an outer casing.
The heater spacer 212 and the outer wall 214 are both made of a metal such as aluminum or stainless steel, or a metal such as an alloy containing these metals as components. The heater spacer 212 and the outer wall 214 are each processed to have the shape of a cylinder with protrusions and recesses by machining.
The heater spacer 212 is formed to have a smaller diameter than the outer wall 214 and is arranged inside (inner circumference side) of the outer wall 214. In other words, the outer wall 214 is arranged outside (outer circumference side) of the heater spacer 212 so as to surround the heater spacer 212.

<<Heater Spacer 212>>

The cartridge-type heater 148 is incorporated in the heater spacer 212. Although only one heater 148 is shown, multiple heaters 148 (for example, four or more) may be arranged in the left and right direction. A conductive lead wire 148a is led out from the heater 148. The lead wire 148a is routed around the heater spacer 212 and electrically connected to the controller 200.
The entire heater spacer 212 is heated by the heater 148. The temperature of the heater spacer 212 may reach over 150°C, for example. The heater spacer 212 is in contact with the threaded spacer 131 so as to enable heat transmission. The exhaust port 15 is inserted and connected to the heater spacer 212. The heat of the heater spacer 212 is transmitted to the threaded spacer 131 and the exhaust port 15 and heats the threaded spacer 131 and the exhaust port 15.
The heater spacer 212 is in contact with the lowermost stator blade spacer 125f, which is the closest to the exhaust port 15 (closest to the base portion 129) among the stator blade spacers 125 (125a, 125b, 125c, ...) so as to allow heat to be transmitted to the lowermost stator blade spacer 125f. The heat of the heater spacer 212 is thus transmitted to the lowermost stator blade spacer 125f, heating the lowermost stator blade spacer 125f and its surroundings.

<<Outer Wall 214>>

The outer wall 214 located outside the heater spacer 212 is thermally insulated from surrounding components. A gap 216 is formed between the outer wall 214 and the heater spacer 212, and the outer wall 214 is arranged so as not to be in direct contact with the heater spacer 212 over the entire circumference.

<<Water-cooled Spacer 125d>>

A water-cooled spacer 125d is provided at one end side of the outer wall 214 in the axial direction (upper side as viewed in Fig. 1). The water-cooled spacer 125d is one of the stator blade spacers 125 (125a, 125b, 125c, ...).
The water-cooled spacer 125d is machined in an annular shape, for example, and constitutes a middle section of the casing 215 in the axial direction. In the illustrated structure, the water-cooled spacer 125d is positioned closer to the inlet port 101 than to the exhaust port 15, but the position can be changed as appropriate depending on the temperature distribution within the turbomolecular pump 100. The process of making the water-cooled spacer 125d may include casting and forging.
A water-cooled pipe 218 is incorporated in the water-cooled spacer 125d, and cooling water flows through the water-cooled pipe 218. The water-cooled spacer 125d is cooled by the water-cooled pipe 218 so that its temperature is adjusted. The water-cooled spacer 125d is not in contact with the heater spacer 212, and other stator blade spacers (the stator blade spacers 125e and 125f in the example of Fig. 5) are interposed between the water-cooled spacer 125d and the heater spacer 212.

<<Heat Insulator Washer 220>>

An annular heat insulator washer (heat insulating ring) 220 is provided between the water-cooled spacer 125d and the outer wall 214. The heat insulator washer 220 is formed to have a gate-shaped (U-shaped) longitudinal cross-section.
The heat insulator washer 220 is interposed between the water-cooled spacer 125d and the outer wall 214. At the outer circumference of the insulator washer 220, a gap 221 is formed between the water-cooled spacer 125d and the outer wall 214. The heat insulator washer 220 and the gap 221 prevent the heat of the water-cooled spacer 125d from being transmitted to the outer wall 214.

<<Cooling by Water-cooled Spacer 125d>>

Of the rotor blades 102 (102a, 102b, 102c, ...) and the stator blades 123 (123a, 123b, 123c, ...) in multiple stages, the rotor blades 102 (such as the rotor blades 102e and 102f) and the stator blades 123 (the stator blades 123e and 123f) on the side corresponding to the exhaust port 15 (the side corresponding to the base portion 129, the downstream side) may be heated to a relatively high temperature (such as about 100°C) as the exhaust gas is transferred.
Also, the stator blades 123 (such as the stator blades 123e and 123f) on the side corresponding to the exhaust port 15 (the side corresponding to the base portion 129, the downstream side) are close to the heater spacer 212 and thus heated to a high temperature also by the heat of the heater spacer 212. Furthermore, the radiant heat from the stator blades 123 (the stator blades 123e and 123f in this example) also heats the rotor blades 102 (the rotor blades 102e and 102f in this example) on the side corresponding to the exhaust port 15 (the side corresponding to the base portion 129). Heating the stator blades 123 and the rotor blades 102 on the side corresponding to the exhaust port 15 (the side corresponding to the base portion 129, the downstream side) can prevent the accumulation of products generated from components of the exhaust gas.
Under the temperature environment described above, the present embodiment includes the water-cooled spacer 125d in the stator blade spacers 125 (125a, 125b, 125c, ...). The water-cooled pipe 218 cools the water-cooled spacer 125d. This alleviates the heat of the stator blade spacers 125 (125e and 125f), the stator blades 123 (the stator blades 123e and 123f in this example), and the rotor blades 102 (the rotor blades 102e and 102f in this example) on the side corresponding to the exhaust port 15 (the side corresponding to the base portion 129).
Also, the heat insulator washer 220 and the gap 216 are interposed between the water-cooled spacer 125d and the outer wall 214. As a result, the water-cooled spacer 125d, the heat insulator washer 220, and the gap 216 adjust the temperature in the heat path between the heater spacer 212 and the outer wall 214, preventing a temperature rise of the outer wall 214. In other words, the outer wall 214 is one of the components whose temperature is adjusted to reduce heat transmission within the casing 215.

<<Heat Insulation by Heat Insulating Cover 210>>

A heat insulating cover 210 is provided outside the outer cylinder 127 and the base portion 129. The heat insulating cover 210 covers substantially the entire circumference of the area of the outer cylinder 127 from the water-cooled spacer 125d to the base portion 129.
As shown in Figs. 6 and 7, the heat insulating cover 210 is constituted by an outlet port cover 222 and a side surface cover 224. The outlet port cover 222 and the side surface cover 224 are separate components, and both are formed of thin plates (sheet metal) with a thickness of about 0.5 mm to several mm.

<<Outlet Port Cover 222>>

The outlet port cover 222 surrounds the exhaust port 15 (the outlet port 133), and covers substantially around the perimeter in the circumferential direction of the exhaust port 15. In other words, the outlet port cover 222 covers substantially around the perimeter (the perimeter of the exhaust port 15 in the circumferential direction) so as to surround the exhaust port 15 (the outlet port 133). This outlet port cover 222 may also be referred to as an "exhaust port cover", for example.
The outlet port cover 222 is constituted of multiple components (two components in the present embodiment) including a first outlet port cover component 222A and a second outlet port cover component 222B. These two outlet port cover components 222A and 222B are sheet metal components made of stainless steel and having a thickness of about 0.5 mm to several mm. Nevertheless, the two outlet port cover components 222A and 222B have a smaller curved area than the side surface cover 224, so that their thickness can be easily increased. The thickness not only has an advantageous effect on heat insulation, but also allows the burrs and edges created at end portions during press working or the like to be easily treated (for example, removed).
Fig. 10(a) shows the second outlet port cover component 222B of the two outlet port cover components 222A and 222B. The second outlet port cover component 222B is curved along the curved surface of the outer cylinder 127. Although not shown, the other first outlet port cover component 222A is similarly curved along the curved surface of the outer cylinder 127.
The first outlet port cover component 222A and the second outlet port cover component 222B are arranged to be linearly symmetrical with respect to a center line A (indicated by the dashed dotted line in Fig. 6). The center line A is a line that is parallel to the axis of the turbomolecular pump 100 and extends through the center of the outlet port 133 in front view.
The shape and arrangement of the two outlet port cover components 222A and 222B are not limited to line symmetry. For example, although not shown, the balance of the sizes of the two outlet port cover components 222A and 222B may be determined such that the center line A extends through one of the two outlet port cover components 222A and 222B.
Also, the center line A does not have to be parallel to the axis of the turbomolecular pump 100. For example, a center line B may be defined intersecting (for example, perpendicular to) the center line A, and the two outlet port cover components 222A and 222B may be arranged to be linearly symmetrical with respect to the center line B.
The two outlet port cover components 222A and 222B can be attached and detached with the side surface cover 224 attached. Allowing the detachment and attachment with the side surface cover 224 attached facilitates the operation when an outlet port heater 226 (described below) is attached to the exhaust port 15, for example, as compared with a situation in which the side surface cover 224 is also removed together or the entire heat insulating cover 210 is removed.
For example, as shown in Fig. 5, according to the application of the turbomolecular pump 100, the outlet port heater 226 (schematically indicated by dashed double-dotted lines) is attached to the exhaust port 15. The outlet port heater 226 is attached to the exhaust port 15 so as to cover the surrounding of the exhaust port 15. The outlet port heater 226 is often attached or detached on-site by a user.
The proximal end of the exhaust port 15 enters a recess 228 of the outer wall 214, and the proximal end of the outlet port heater 226 also reaches a deep side of the recess 228 of the outer wall 214. When the outlet port heater 226 is attached, the proximal end of the outlet port heater 226 is inserted into the recess 228 of the outer wall 214.
When such attachment of the outlet port heater 226 is performed with the heat insulating cover 210 (the two outlet port cover components 222A and 222B in this example) attached, the outlet port heater 226 may be pushed in while interfering with the heat insulating cover or the like. This may deform the heat insulating cover or the like.
In this respect, removing the two outlet port cover components 222A and 222B widens the field of view for operation. This allows the attachment operation of the outlet port heater 226 to be correctly performed. Furthermore, the range of operation for removal is small, increasing the ease and workability of removal and reattachment as compared with a situation in which the entire heat insulating cover 210 is removed.
Additionally, in the present embodiment, the two outlet port cover components 222A and 222B are attached to the outer wall 214. The two outlet port cover components 222A and 222B are attached using fall prevention screws 230. As the fall prevention screws 230, screws of various general types may be used. In this embodiment, combinations of fall prevention cross recessed pan head screws and fall prevention washers (not shown) are used.
Although not shown, each fall prevention cross recessed pan head screw has a thread portion radially protruding from the shaft portion. The fall prevention cross recessed pan head screw is inserted such that the fall prevention washer is sandwiched between the fall prevention cross recessed pan head screw and the first outlet port cover component 222A (or the second outlet port cover component 222B). When a fall prevention cross recessed pan head screw is loosened, the thread portion is caught in the recessed section of the fall prevention washer to prevent the fall prevention cross recessed pan head screw from falling off.
As such fall prevention cross recessed pan head screws and fall prevention washers, those manufactured by Nabeya Bi-tech Kaisha may be used, for example.
The fixing of the two outlet port cover components 222A and 222B does not have to be achieved with screws, and other fasteners may also be used. Examples of fasteners other than screws include hook-and-loop fasteners (with sufficient heat resistance).

<<Side Surface Cover 224>>

The above-mentioned side surface cover 224 covers the side surface of the turbomolecular pump 100 except for the surrounding of the exhaust port 15. The side surface cover 224 and the outlet port cover 222 cover the side surface of the turbomolecular pump 100 approximately 360 degrees.
The side surface cover 224 is divided into multiple (two in this example) parts in the circumferential direction of the turbomolecular pump 100, and is constituted by a first side surface cover component 224A and a second side surface cover component 224B. The two side surface cover components 224A and 224B are sheet metal components made of stainless steel and having a thickness of about 0.5 mm to several mm.
Fig. 10(b) shows the second side surface cover component 224B of the two side surface cover components 224A and 224B. The second side surface cover component 224B curves along the curved surfaces of the outer wall 214, the water-cooled spacer 125d, and the base portion 129. Although not shown, the other first side surface cover component 224A is similarly curved along the curved surfaces of the outer wall 214, the water-cooled spacer 125d, and the base portion 129.
In the present embodiment, the two side surface cover components 224A and 224B are attached to the outer wall 214. The two side surface cover components 224A and 224B are also attached with fall prevention screws 230. As the fall prevention screws 230, screws of various general types may be used as with the two outlet port cover components 222A and 222B.

<<Limitation of Surface Temperature of Outlet Port Cover 222 and Side Surface Cover 224>>

As described above, the outlet port cover 222 and the side surface cover 224 are fixed to the outer wall 214. The gap 216 is interposed between the outer wall 214 and the heater spacer 212. Also, the heat insulator washer 220 is interposed between the outer wall 214 and the water-cooled spacer 125d.
As described above, the temperature of the heater spacer 212 may reach over 150°C, and the temperatures of the rotor blades 102 (such as the rotor blades 102e and 102f) and the stator blades 123 (such as the stator blades 123e and 123f) on the side corresponding to the exhaust port 15 (the side corresponding to the base portion 129, the downstream side) may become about 100°C, for example.
Under such a temperature environment, the surface temperatures of the outlet port cover 222 and the side surface cover 224 are limited to 65°C or less, as indicated by a result of measurement. This is because the temperature of the outer wall 214, which is in contact with the outlet port cover 222 and the side surface cover 224, of the turbomolecular pump 100 of the present embodiment is adjusted with respect to the heat inside the casing 215. Another reason is that the heat insulator washer 220 and the gap 221 are interposed between the outer wall 214 and the water-cooled spacer 125d.

<<Measure to Improve Strength of Side Surface Cover 224>>

A measure to improve strength is provided in the side surface cover 224. In the present embodiment, sheet metal bending is employed as the measure to improve strength. The measure to improve strength limits deformation of the side surface cover 224.
As shown in Fig. 10(b), a bent structure is employed at one end of the second side surface cover component 224B in the longitudinal direction (the circumferential direction of the turbomolecular pump 100). The bent structure is formed by bending an end portion of the second side surface cover component 224B inward (inner circumference surface side) with a width of about several millimeters (such as 5 mm) to provide a bent portion 232B.
As shown in Fig. 6, the second side surface cover component 224B is attached to the outer wall 214 with the bent portion 232B directed toward the second outlet port cover component 222B.
A similar structure is employed for the first side surface cover component 224A. As shown in Fig. 6, the first side surface cover component 224A is attached to the outer wall 214 with a bent portion 232A directed toward the first outlet port cover component 222A.
Providing such bent portions 232A and 232B increases the rigidity at one end of each of the two side surface cover components 224A and 224B, improving the strength of the side surface cover 224. Also, the bent portions 232A and 232B fill the gap between the end portion of the first side surface cover component 224A and the recess 228 of the outer wall 214 and the gap between the end portion of the second side surface cover component 224B and the recess 228 of the outer wall 214 over the width C of the bent portions 232A and 232B (indicated for the bent portion 232B in Fig. 10(b)).
When such a measure to improve strength is not provided, any excessive load or impact applied from the outside to the boundaries between the two side surface cover components 224A and 224B and the two outlet port cover components 222A and 222B may deform the two side surface cover components 224A and 224B and the two outlet port cover components 222A and 222B. This may cause the gaps 234A and 234B (Fig. 6) to widen to about 10 mm, for example, enabling entry of fingers of the operator, tools, or the like.
The area around the exhaust port 15 tends to become hot, and entry of fingers or tools into the gaps 234A and 234B may result in the fingers or tools coming into contact with a hot section. Also, since the lead wire 148a for the heater 148 and electrical terminals are provided around the heater spacer 212, the inserted fingers may come into contact with these electrical system components. As such, it is important to prevent fingers and tools from entering the gaps 234A and 234B.
Furthermore, providing the measure to improve strength described above reinforces the two side surface cover components 224A and 224B, thereby improving the rigidity at the ends of the two side surface cover components 224A and 224B. This allows for the prevention of deformation of the two side surface cover components 224A and 224B and the prevention of widening of the gaps 234A and 234B. Additionally, entry of fingers of the operator or tools into the gaps 234A and 234B can also be prevented.
Taking into consideration not only the rigidity but also heat insulation, it is desirable not to increase the area of the portions of the two side surface cover components 224A and 224B that are in contact with the outer wall 214. For this reason, the relationship between the bent portions 232A and 232B and the recess 228 of the outer wall 214 is set such that the width C of the bent portions 232A and 232B (indicated for the bent portion 232B in Fig. 10(b)) is accommodated within the recess 228 of the outer wall 214.
In this manner, it is possible to prevent the bent portions 232A and 232B from coming into contact with the outer wall 214, and prevent an increase in the area of the portions of the two side surface cover components 224A and 224B that come into contact with the outer wall 214.
Although not shown, bent portions (for example, those similar to the bent portions 232A and 232B) may be provided at end portions 236A and 236B of the two side surface cover components 224A and 224B facing each other. In this case, even if an impact is applied to the end portions 236A and 236B of the two side surface cover components 224A and 224B, deformation of the two side surface cover components 224A and 224B is prevented.
The measure to improve strength described above can be applied not only to the two side surface cover components 224A and 224B but also to the two outlet port cover components 222A and 222B, for example. Although not shown, the two outlet port cover components 222A and 222B may have bent portions (for example, those similar to the bent portions 232A and 232B).
The measure to improve strength is not limited to sheet metal bending. For example, as shown in a modification (which may be a second embodiment) of Fig. 11, the measure to improve strength may be the placement of strut members 238. A turbomolecular pump 260 of the type shown in Fig. 11 has a clearance 242 formed between the outlet port cover 222 and the outer wall 214. A clearance 244 is also formed between the side surface cover 224 and the outer wall 214.
The strut members 238 are placed in these clearances 242 and 244. Multiple (such as eight) strut members 238 are placed around the outer wall 214. The cross-section of each strut member 238 has the shape of a cylinder of perfect circle (the shape of a collar, the shape of a sleeve).
In the example of Fig. 11, the shaft portion of a fall prevention screw 230 extends through each strut member 238, and the strut member 238 surrounds the entire circumference of the shaft portion of the fall prevention screw 230. One axial end of the strut member 238 is in contact with the outer wall 214, and the multiple ends are in contact with one of the two outlet port cover components 222A and 222B and the two side surface cover components 224A and 224B.
When there is the clearance 242 between the outlet port cover 222 and the outer wall 214 and the clearance 244 between the side surface cover 224 and the outer wall 214, providing the above strut members 238 reinforces the outlet port cover 222 and the side surface cover 224 because the outlet port cover 222 and the side surface cover 224 are not simply suspended relative to the outer wall 214. Also, the gaps are prevented from widening to an extent that enables entry of fingers of the operator or tools due to deformation of the outlet port cover 222 or the side surface cover 224.
In the turbomolecular pump 260 of Fig. 11, in addition to the measure to improve strength as described above, heat insulation by the strut members 238 and the like is also achieved. It is of a type in which the heat insulator washer 220 in the turbomolecular pump 100 of the example of Fig. 5 is omitted, and, instead of the heat insulator washer 220, the clearances 242 and 244 are interposed between the outer wall 214 and the outlet port cover 222 and the side surface cover 224. Forming the clearances 242 and 244 allows the turbomolecular pump 260 of Fig. 11 to limit an increase in the temperatures of the outlet port cover 222 and the side surface cover 224.
Also, in the example of Fig. 11, each strut member 238 is in contact with the outer wall 214 and the outlet port cover 222 or the side surface cover 224. As such, the strut member 238 functions not only as a reinforcing material but also as a heat insulating material. The strut member 238 can prevent heat from being transmitted from the outer wall 214 to the outlet port cover 222 or the side surface cover 224.
The configuration shown in Fig. 11 is suitable for a type of turbomolecular pump in which the temperature of the outer wall 214 tends to be higher than the configuration shown in Fig. 5.
In the example of Fig. 11, the strut members 238 are cylindrical and fixed through the fall prevention screws 230. However, the configuration is not limited to this, and the strut members 238 can be solid rod-shaped members. In this case, although not shown, the strut members 238 may be fixed by various general methods.
For example, external threads may be formed at both ends of each strut member 238 in the axial direction. One external thread portion is threaded in the outer wall 214 and connected to the outer wall 214. The other external thread portion is inserted through a hole in one of the two outlet port cover components 222A and 222B and the two side surface cover components 224A and 224B, and is fixed to one of the two outlet port cover components 222A and 222B and the two side surface cover components 224A and 224B by tightening a nut from the outside.

<<Other Advantages of Turbomolecular Pumps 100 and 260>>

According to the turbomolecular pump 100 (e.g., Fig. 5) of the present embodiment and the turbomolecular pump 260 (Fig. 11) of the modification, in addition to the advantages described above, the edges of the step portions of the outer wall 214, which is a component formed by machining and not a component formed of sheet metal, can be easily chamfered with a large R (curvature radius). Thus, safety is easily ensured regarding contact between the user's finger and an edge of the outer wall 214.

<<Invention that can be Extracted from Embodiments>>

The following inventions can be extracted from the embodiments described above.

(1) A vacuum pump (such as the turbomolecular pump 100) including:
- a casing (such as the casing 215 including the outer cylinder 127, the outer wall 214, and the heater spacer 212) including at least an outlet port (such as the outlet port 133) of an inlet port (such as the inlet port 101) and the outlet port; and
- a heating means (such as the heater 148) for causing a portion of at least the casing of the casing and the outlet port to have a high temperature, wherein
- the vacuum pump comprises:
  - an annular side surface cover (such as the side surface cover 224) that covers a side surface of the casing and has a shape of a thin plate; and
  - an outlet port cover (such as the outlet port cover 222) that covers a surrounding of the outlet port and has a shape of a thin plate, and
  - the outlet port cover is a member separate from the side surface cover and is attachable and detachable with the side surface cover attached.
(2) The vacuum pump according to (1), wherein the outlet port cover covers substantially around a perimeter so as to surround the outlet port, and is constituted by at least two components.
(3) The vacuum pump according to (2), wherein the outlet port cover is a structure that is divided so as to be linearly symmetrical with respect to a center line (such as the center line A) extending through a center of the outlet port.
(4) The vacuum pump according to (1), wherein
- a clearance (such as the clearance 242, 244) is disposed between the side surface cover or the outlet port cover and the casing, and
- a measure to improve strengths (such as providing the bent portions 232A and 232B, providing the strut members 238) is provided to reduce deformation of the side surface cover or the outlet port cover at the clearance.
(5) The vacuum pump according to (4), wherein the measure to improve strength uses a structure in which at least one end of the side surface cover or the outlet port cover is bent toward the casing (such as a structure including the bent portions 232A and 232B).
(6) The vacuum pump according to (4), wherein the measure to improve strength uses a strut structure (such as a structure including the strut members 238) placed between the casing and the side surface cover or the outlet port cover.
(7) The vacuum pump according to any one of (1) to (6), wherein a temperature of a section of the casing in which the side surface cover or the outlet port cover is placed is adjusted by a temperature adjusting means (such as the heater 148).
(8) The vacuum pump according to any one of (1) to (6), wherein the casing is formed of a double structure including an inner casing (such as the heater spacer 212) that is a structure configured to retain a vacuum pump in an exhaust flow passage in the vacuum pump and an outer casing (such as the outer wall 214) covering a surrounding of the inner casing.

The present invention is not limited to the above-described embodiments, and various modifications and combinations of the embodiments can be made without departing from the scope of the invention.

15: Exhaust port
100, 260: Turbomolecular pump
101: Inlet port
102: Rotor blade
103: Rotating body
123: Stator blade
125: Stator blade spacer
125d: Water-cooled spacer
133: Outlet port
148: Heater
148a: Lead wire
149: Water-cooled tube
210: Heat insulating cover
212: Heater spacer
214: Outer wall
215: Casing
216: Gap
218: Water-cooled tube
220: Heat insulator washer
222: Outlet port cover
222A: First outlet port cover component
222B: Second outlet port cover component
224: Side surface cover
224A: First side surface cover component
224B: Second side surface cover component
226: Outlet port heater
228: Recess
230: Fall prevention screw
232A, 232B: Bent portion
234A, 234B: Gap
238: Strut member
242, 244: Clearance

Claims

A vacuum pump comprising:
a casing including at least an outlet port from among an inlet port and the outlet port; and

a heating means for causing a portion of at least the casing to have a high temperature, from among the casing and the outlet port, wherein

the vacuum pump includes:
a surface cover that covers a side surface of the casing, the side surface cover having an annular shape and a thin plate shape; and

an outlet port cover that covers a surrounding of the outlet port, the outlet port cover having a thin plate shape, and

the outlet port cover is a member separate from the side surface cover and is attachable and detachable, with the side surface cover being attached.
The vacuum pump according to claim 1, wherein the outlet port cover covers the outlet port so as to surround substantially a perimeter thereof, and is constituted of at least two components.
The vacuum pump according to claim 2, wherein the outlet port cover is a structure that is divided so as to be linearly symmetrical with respect to a center line extending through a center of the outlet port.
The vacuum pump according to claim 1, wherein
a clearance is disposed between the side surface cover or the outlet port cover and the casing, and

a measure to improve strength is provided at the clearance to reduce deformation of the side surface cover or the outlet port cover.
The vacuum pump according to claim 4, wherein the measure to improve strength uses a structure in which at least one end of the side surface cover or the outlet port cover is bent toward the casing.
The vacuum pump according to claim 4, wherein the measure to improve strength uses a strut structure placed between the casing and the side surface cover or the outlet port cover.
The vacuum pump according to any one of claims 1 to 6, wherein a temperature of a section, in which the side surface cover or the outlet port cover is placed, of the casing is adjusted by a temperature adjusting means.
The vacuum pump according to any one of claims 1 to 6, wherein the casing is formed of a double structure including an inner casing that is a structure configured to retain a vacuum in an exhaust flow passage in the vacuum pump and an outer casing covering a surrounding of the inner casing.