JP7598396B2 - Vacuum pump - Google Patents

Description

The present invention relates to a vacuum pump, such as a turbomolecular pump.

Turbomolecular pumps are generally known as a type of vacuum pump. In these turbomolecular pumps, a motor inside the pump body is energized to rotate rotors, which eject the gas molecules of the gas (process gas) sucked into the pump body, thereby discharging the gas. Some turbomolecular pumps are equipped with heaters and cooling tubes to properly manage the temperature inside the pump.

In addition, Patent Document 1 (see paragraphs 0005, 0006, etc.) below discloses that the base is provided with a cover member that covers the base via an air insulation layer, thereby preventing the user from coming into contact with a hot part.

JP 2022-158145 A

Patent Document 1 (paragraph 0029, etc.) discloses that the outer periphery of the base is covered with a cover member to prevent the user from touching the base, which is a hot part, and that heat is not transferred to the cover member, and that the cover member is cooled. However, further improvements are needed to further improve the safety of the vacuum pump.

The objective of the present invention is to provide a vacuum pump that can further improve safety.

In order to achieve the above object, the vacuum pump according to the present invention comprises:
a casing provided with at least the exhaust port among an intake port and an exhaust port;
a heating means for heating at least a part of the casing and the exhaust port to a high temperature;
A vacuum pump comprising:
The vacuum pump is
a ring-shaped thin plate-shaped side cover that covers a side surface of the casing;
A thin plate-shaped exhaust port cover that covers the periphery of the exhaust port;
having
The exhaust port cover is a separate part from the side cover, and is removable even when the side cover is attached.

The above invention provides a vacuum pump that can further improve safety.

1 is an explanatory diagram illustrating a schematic configuration of a turbomolecular pump according to an embodiment of the present invention. FIG. 2 is a circuit diagram of an amplifier circuit. 6 is a time chart showing control when a current command value is larger than a detection value. 6 is a time chart showing control when a current command value is smaller than a detection value. FIG. 2 is an explanatory diagram showing the configuration of the turbomolecular pump that is the same as that of FIG. 1, but with different reference numerals assigned to different portions. FIG. 2 is a side view showing the side where an exhaust port 15 of the turbo molecular pump is provided. FIG. 2 is a side view showing the turbomolecular pump with the side on which the exhaust port 15 is provided facing backward. FIG. 7 is a side view showing the turbomolecular pump of FIG. 6 with a second exhaust port cover part 222B and a second side cover part 224B removed. FIG. 8 is a side view of the turbomolecular pump of FIG. 7 with the second side cover part 224B removed. 1A is a perspective view showing a second exhaust port cover part 222B, and FIG. 1B is a perspective view showing a second side surface cover part 224B. FIG. 13 is an explanatory diagram illustrating a schematic configuration of a turbomolecular pump according to a modified example.

First Embodiment
A vacuum pump according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows a turbomolecular pump 100 as a vacuum pump according to a first embodiment of the present invention. This turbomolecular pump 100 is adapted to be connected to a vacuum chamber (not shown) of a target device such as a semiconductor manufacturing device.

<<Basic Configuration of Turbomolecular Pump 100>>
A longitudinal cross-sectional view of this turbomolecular pump 100 is shown in Fig. 1. In Fig. 1, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer tube 127. Inside the outer tube 127, a rotor 103 is provided, the rotor 103 having a plurality of rotors 102 (102a, 102b, 102c, ...) which are turbine blades for sucking in and exhausting gas, formed radially on its periphery in multiple stages. A rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing.

The upper radial electromagnets 104 are arranged in pairs on the X-axis and Y-axis. Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to each of the upper radial electromagnets 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on the change in inductance of the conductive windings, which changes according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send it to the control device 200 shown by the dashed line.

In this control device 200, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on the position signal detected by the upper radial sensor 107, and the amplifier circuit 150 (described later) shown in FIG. 2 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

The rotor shaft 113 is made of a material with high magnetic permeability (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. The lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107, and adjust the lower radial position of the rotor shaft 113 in the same manner as the upper radial position.

Furthermore, the axial electromagnets 106A and 106B are arranged above and below a circular metal disk (also called an "armature disk") 111 provided at the bottom of the rotor shaft 113. The metal disk 111 is made of a highly magnetic permeable material such as iron. An axial sensor 109 is provided to detect the axial displacement of the rotor shaft 113, and the axial position signal is sent to the control device 200.

In the control device 200, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

In this way, the control device 200 appropriately adjusts the magnetic force that the axial electromagnets 106A and 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. The amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

On the other hand, the motor 121 has multiple magnetic poles arranged circumferentially to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 so as to rotate the rotor shaft 113 via electromagnetic forces acting between the magnetic poles and the rotor shaft 113. In addition, the motor 121 incorporates a rotational speed sensor, such as a Hall element, resolver, or encoder (not shown), and the rotational speed of the rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

In addition, a phase sensor (not shown) is attached, for example, near the lower radial sensor 108, to detect the phase of rotation of the rotor shaft 113. The control device 200 uses the detection signals of both this phase sensor and the rotation speed sensor to detect the position of the magnetic poles.

Multiple fixed blades 123 (123a, 123b, 123c...) are arranged with a small gap (predetermined interval) between the rotor blades 102 (102a, 102b, 102c...). The rotor blades 102 (102a, 102b, 102c...) are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward by collision.

The fixed blades 123 are also formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged in a staggered manner with the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral end of the fixed blades 123 is supported by being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, ...).

The fixed wing spacer 125 is a ring-shaped member, and is made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a small gap between them. A base portion 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129, and is connected to the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) side and is transferred to the base portion 129 is sent to the exhaust port 133.

Furthermore, depending on the application of the turbomolecular pump 100, a threaded spacer 131 is disposed between the lower part of the fixed vane spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical member made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has a plurality of helical thread grooves (not shown) engraved on its inner circumferential surface. The helical direction of the thread groove (not shown) is the direction in which the molecules of the exhaust gas are transported toward the exhaust port 133 when they move in the rotation direction of the rotor 103. The rotor lower cylindrical part 103b is suspended from the lower part of the rotor main body 103a on which the rotor vanes 102 (102a, 102b, 102c, ...) of the rotor 103 are formed. The outer peripheral surface of the rotor lower cylindrical portion 103b is cylindrical and protrudes toward the inner peripheral surface of the threaded spacer 131, and is adjacent to the inner peripheral surface of the threaded spacer 131 with a specified gap between them. The exhaust gas transferred to the thread groove (not shown) by the rotor 102 and the fixed blade 123 is guided by the thread groove (not shown) and sent to the base portion 129. In this way, the threaded spacer 131 and the rotor lower cylindrical portion 103b facing it constitute a Holweck type exhaust mechanism. The Holweck type exhaust mechanism gives directionality to the exhaust gas by the rotation of the rotor lower cylindrical portion 103b relative to the threaded spacer 131, improving the exhaust characteristics of the turbo molecular pump 100.

The base portion 129 is a disk-shaped member that forms the base of the turbomolecular pump 100, and is generally made of a metal such as iron, aluminum, or stainless steel. The base portion 129 not only physically holds the turbomolecular pump 100, but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the rotor 102 and the fixed blades 123 act to draw exhaust gas from the chamber through the intake port 101. The exhaust gas drawn in through the intake port 101 passes between the rotor 102 and the fixed blades 123 and is transferred to the base 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and the conduction of heat generated by the motor 121, but this heat is transferred to the fixed blades 123 by radiation or conduction by gas molecules (gas molecules) of the exhaust gas.

The fixed blade spacers 125 are joined together at their outer periphery and transmit to the outside heat received by the fixed blades 123 from the rotor blades 102 and frictional heat generated when exhaust gas comes into contact with the fixed blades 123.

In the above description, the threaded spacer 131 is disposed on the outer periphery of the lower cylindrical portion 103b of the rotor 103, and a thread groove (not shown) is engraved on the inner periphery of the threaded spacer 131. However, conversely, there are also cases where a thread groove is engraved on the outer periphery of the lower cylindrical portion 103b of the rotor, and a spacer having a cylindrical inner periphery is disposed around it.

Depending on the application of the turbomolecular pump 100, the electrical equipment section may be covered by a stator column 122 to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section, which is composed of the upper radial electromagnet 104, upper radial sensor 107, motor 121, lower radial electromagnet 105, lower radial sensor 108, axial electromagnets 106A and 106B, and axial sensor 109, and the inside of the stator column 122 may be kept at a predetermined pressure by a purge gas (protective gas).

In this case, a pipe for introducing purge gas (also called a "purge gas port", not shown) is provided in the base portion 129, and purge gas is introduced through this pipe. The introduced purge gas is sent to the exhaust port 133 through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, between the stator column 122 and the inner cylindrical portion of the rotor 102 (lower cylindrical portion 103b of the rotor) and between the base portion 129.

The turbomolecular pump 100 requires control based on the model identification and individually adjusted unique parameters (e.g., various characteristics corresponding to the model). To store these control parameters, the turbomolecular pump 100 has an electronic circuit section within its body. The electronic circuit section is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor elements for accessing the memory, and a substrate for mounting these components. This electronic circuit section is housed below a rotational speed sensor (not shown), for example near the center of the base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom cover 145.

In the semiconductor manufacturing process, some process gases introduced into the chamber have the property of becoming solid when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. If the pressure of the process gas becomes higher than a predetermined value or its temperature falls below a predetermined value while the process gas is being transferred from the intake port 101 to the exhaust port 133, the process gas becomes solid and adheres to and accumulates inside the turbomolecular pump 100.

For example, when _SiCl4 is used as a process gas in an Al etching apparatus, at low vacuum (760 [torr] to 10 ^-2 [torr]) and low temperature (about 20 [°C]), a solid product (e.g. _AlCl3 ) precipitates and accumulates inside the turbomolecular pump 100, as can be seen from the vapor pressure curve. As a result, when precipitates of the process gas accumulate inside the turbomolecular pump 100, the deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The above-mentioned product is prone to solidification and adhesion in high pressure areas near the exhaust port and near the threaded spacer 131.

Therefore, in order to solve this problem, conventionally, a heater (not shown) or an annular (ring-shaped) water-cooled tube 149 is wrapped around the outer periphery of the base part 129, and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base part 129, and the heating of the heater and the cooling by the water-cooled tube 149 are controlled based on the signal from this temperature sensor to keep the temperature of the base part 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; TMS; Temperature Management System).

Next, regarding the turbomolecular pump 100 configured in this manner, we will explain the amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B. A circuit diagram of this amplifier circuit is shown in Figure 2.

In FIG. 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to the positive pole 171a of the power supply 171 via the transistor 161, and the other end is connected to the negative pole 171b of the power supply 171 via the current detection circuit 181 and the transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

At this time, the transistor 161 has its diode cathode terminal 161a connected to the positive electrode 171a, and its anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has its diode cathode terminal 162a connected to the current detection circuit 181, and its anode terminal 162b connected to the negative electrode 171b.

On the other hand, the current regeneration diode 165 has its cathode terminal 165a connected to one end of the electromagnet winding 151 and its anode terminal 165b connected to the negative pole 171b. Similarly, the current regeneration diode 166 has its cathode terminal 166a connected to the positive pole 171a and its anode terminal 166b connected to the other end of the electromagnet winding 151 via a current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall sensor type current sensor or an electrical resistance element.

The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled on five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) (not shown) of the control device 200, and this amplifier control circuit 191 is configured to switch the transistors 161 and 162 on and off.

The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Then, based on the result of this comparison, it determines the size of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control. As a result, gate drive signals 191a, 191b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of transistors 161, 162.

When the rotor 103 passes through a resonance point during accelerated operation or when a disturbance occurs during constant speed operation, it is necessary to control the position of the rotor 103 at high speed and with strong force. For this reason, a high voltage of, for example, about 50 V is used as the power supply 171 so that the current flowing through the electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between the positive pole 171a and the negative pole 171b of the power supply 171 to stabilize the power supply 171.

In this configuration, when both transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereafter referred to as electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

Furthermore, when one of the transistors 161, 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By passing a flywheel current through the amplifier circuit 150 in this manner, the hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Furthermore, by controlling the transistors 161, 162 in this manner, high-frequency noise such as harmonics generated in the turbo molecular pump 100 can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.

In other words, when the detected current value is smaller than the current command value, both transistors 161 and 162 are turned on for a time period equivalent to pulse width time Tp1 only once during control cycle Ts (e.g., 100 μs) as shown in FIG. 3. Therefore, during this period, electromagnet current iL increases toward current value iLmax (not shown) that can flow from positive pole 171a to negative pole 171b via transistors 161 and 162.

On the other hand, if the detected current value is greater than the current command value, both transistors 161 and 162 are turned off for a time period equivalent to pulse width time Tp2 only once during control cycle Ts, as shown in FIG. 4. Therefore, during this period, the electromagnet current iL decreases from negative pole 171b to positive pole 171a toward a current value iLmin (not shown) that can be regenerated via diodes 165 and 166.

In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, during this period, a flywheel current is maintained in the amplifier circuit 150.

The turbomolecular pump 100 having such a basic configuration has an intake section connected to the target device on the upper side in FIG. 1 (the side of the intake port 101), and an exhaust section connected to an auxiliary pump (back pump) (not shown) on the lower side (the side on which the exhaust port 15 constituting the exhaust port 133 is provided on the base portion 129 so as to protrude to the right side in the figure). The turbomolecular pump 100 can be used not only in the vertical position shown in FIG. 1, but also in an inverted position, horizontal position, or inclined position.

In the turbomolecular pump 100, the outer cylinder 127 described above, the heater spacer 212 described below, the outer wall 214 described below, and the base portion 129 are combined to form a casing 215. The casing 215 will be described later. The turbomolecular pump 100 in the example of FIG. 1 also includes a circular box-shaped electrical equipment case 198, and the control device 200 described above is disposed within the electrical equipment case 198.

The internal structure of the casing 215 of the turbomolecular pump 100 can be divided into a rotation mechanism that rotates the rotor shaft 113, etc., by the motor 121, and an exhaust mechanism that is driven to rotate by the rotation mechanism. The exhaust mechanism can be divided into a turbomolecular pump mechanism that is composed of the rotor 102, fixed blades 123, etc., and a threaded pump mechanism (Holbeck-type exhaust mechanism) that is composed of the rotor lower cylindrical portion 103b, threaded spacer 131, etc.

The aforementioned purge gas (protective gas) is used to protect the bearing parts and the rotor 102, etc., to prevent corrosion caused by exhaust gas (process gas), and to cool the rotor 102. This purge gas can be supplied by a general method.

For example, a purge gas port (not shown) extending linearly in the radial direction is provided at a predetermined location of the base portion 129 (such as a position approximately 180 degrees away from the exhaust port 133). Purge gas is then supplied to this purge gas port from the outside of the base portion 129 via a purge gas cylinder (such as an N2 gas cylinder) or a flow rate regulator (valve device).

The protective bearings 120 mentioned above are also called "touch-down (T/D) bearings" or "backup bearings." These protective bearings 120 prevent the position or attitude of the rotor shaft 113 from changing significantly, and prevent damage to the rotor blades 102 and their surroundings, even in the unlikely event of a problem with the electrical system or atmospheric inrush.

In addition, in FIG. 1, which shows the structure of the turbomolecular pump 100 and the rotor 103, hatching showing cross sections of parts has been omitted except for the heater 148 to avoid cluttering the drawing.

<<Configuration of casing 215>>
Fig. 5 shows the internal structure of the turbomolecular pump 100 in this embodiment, similar to Fig. 1. In Fig. 1, in order to avoid the illustration becoming complicated, the details of the casing 215 and the reference numerals relating to the heat insulating cover 210 described later are omitted.

In FIG. 5, details of the casing 215 and reference symbols for the insulating cover 210, which will be described later, are shown. Also, in FIG. 5, hatching is used only for some of the components (heater 148, outer wall 214, heat insulator washer 220) to clearly distinguish them from the surrounding components.

The casing 215 has a partially double structure. The section of the casing 215 from the midway axial position to the base portion 129 is constructed using a heater spacer 212 and an outer wall 214. As will be described in detail later, the heater spacer 212 is a structure that ensures a vacuum in the exhaust flow path within the turbo molecular pump 100, and constitutes the inner casing. The outer wall 214 is a structure that covers the periphery of the heater spacer 212, and constitutes the outer casing.

The heater spacer 212 and the outer wall 214 are both made of metals such as aluminum, stainless steel, or alloys containing these metals. The heater spacer 212 and the outer wall 214 are machined into an uneven cylindrical shape by cutting.

The heater spacer 212 is formed with a smaller diameter than the outer wall 214 and is disposed inside (on the inner periphery side) of the outer wall 214. In other words, the outer wall 214 is disposed outside (on the outer periphery side) of the heater spacer 212 and disposed so as to surround the heater spacer 212.

<<Heater Spacer 212>>
A cartridge-type heater 148 is incorporated in the heater spacer 212. Although only one heater 148 is shown in the figure, multiple heaters 148 (e.g., four or more) may be arranged in the left-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 is electrically connected to the control device 200.

The heater spacer 212 is heated all over by the heater 148. The temperature of the heater spacer 212 may reach, for example, a little over 150°C. The heater spacer 212 is in contact with the threaded spacer 131 described above so as to enable heat transfer. The exhaust port 15 is inserted and connected to the heater spacer 212. The heat of the heater spacer 212 is transferred to the threaded spacer 131 and the exhaust port 15, and the threaded spacer 131 and the exhaust port 15 are heated.

The heater spacer 212 is in contact with the bottom-most fixed wing spacer 125f, which is located closest to the exhaust port 15 (the base portion 129 side) among the fixed wing spacers 125 (125a, 125b, 125c, etc.), so that heat can be transferred to it. The heat of the heater spacer 212 is also transferred to the bottom-most fixed wing spacer 125f, heating the bottom-most fixed wing spacer 125f and its surroundings.

<<Outer Wall 214>>
An outer wall 214 located on the outside of the heater spacer 212 provides thermal insulation from surrounding components. A gap 216 is provided between the outer wall 214 and the heater spacer 212, and the outer wall 214 is disposed so as not to directly contact the heater spacer 212 over the entire periphery.

<<Water-cooled spacer 125d>>
A water-cooled spacer 125d is provided on one axial end side (upper side in FIG. 1) of the outer wall 214. The water-cooled spacer 125d is one of the fixed wing spacers 125 (125a, 125b, 125c, ...).

The water-cooled spacer 125d is formed into an annular shape, for example, by machining, and constitutes a portion of the casing 215 in the axial direction. In this structure, the water-cooled spacer 125d is located closer to the intake port 101 than the exhaust port 15, but the position can be changed as appropriate depending on the temperature distribution inside the turbomolecular pump 100. The water-cooled spacer 125d may be manufactured by casting or forging.

The water-cooled spacer 125d incorporates a water-cooled pipe 218 through which cooling water flows. The water-cooled spacer 125d is cooled by the water-cooled pipe 218 to adjust the temperature. The water-cooled spacer 125d is not in contact with the heater spacer 212, and other fixed wing spacers (fixed wing 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 (thermal insulation 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) cross section in vertical cross section.

The heat insulator washer 220 is interposed between the water-cooled spacer 125d and the outer wall 214. A gap 221 is formed between the water-cooled spacer 125d and the outer wall 214 on the outer periphery of the insulator washer 220. The heat insulator washer 220 and the gap 221 prevent the heat of the water-cooled spacer 125d from being transferred to the outer wall 214.

<<Cooling by Water-Cooling Spacer 125d>>
Of the multi-stage rotors 102 (102a, 102b, 102c...) and stators 123 (123a, 123b, 123c...), the rotors 102 (e.g., rotors 102e, 102f) and stators 123 (e.g., stators 123e, 123f) on the exhaust port 15 side (base portion 129 side, downstream side) may become relatively hot (e.g., around 100°C) due to the transport of exhaust gas.

In addition, the fixed vanes 123 (here, fixed vanes 123e, 123f) on the exhaust port 15 side (base portion 129 side, downstream side) are close to the heater spacer 212, so they also become hot due to the heat of the heater spacer 212. Furthermore, the rotor 102 (here, rotor 102e, 102f) on the exhaust port 15 side (base portion 129 side) also becomes hot due to the radiant heat from the fixed vanes 123 (here, fixed vanes 123e, 123f). By raising the temperature of the fixed vanes 123 and rotor 102 on the exhaust port 15 side (base portion 129 side, downstream side), it is possible to prevent the accumulation of products made from exhaust gas components.

In this embodiment, to cope with such a temperature environment, the fixed wing spacer 125 (125a, 125b, 125c, ...) includes a water-cooled spacer 125d. The water-cooled spacer 125d is cooled by a water-cooled pipe 218. This reduces the heat of the fixed wing spacer 125 (125e, 125f), the fixed wing 123 (here, fixed wings 123e, 123f), and the rotor 102 (here, rotor 102e, 102f) on the exhaust port 15 side (base portion 129 side).

In addition, the heat insulator washer 220 and the gap 216 are interposed between the water-cooled spacer 125d and the outer wall 214. Therefore, in the heat path between the heater spacer 212 and the outer wall 214, the water-cooled spacer 125d, the heat insulator washer 220, and the gap 216 adjust the temperature, preventing the temperature of the outer wall 214 from rising. In other words, the outer wall 214 is one of the components whose temperature is adjusted so that heat inside the casing 215 is not easily transmitted.

<<Insulation by the Insulating Cover 210>>
A heat insulating cover 210 is provided on the outside of the outer cylinder 127 and the base portion 129. The heat insulating cover 210 covers the range from the water-cooled spacer 125d of the outer cylinder 127 to the base portion 129 over almost the entire circumference.

As shown in Figures 6 and 7, the heat insulating cover 210 is composed of an exhaust port cover 222 and a side cover 224. The exhaust port cover 222 and the side cover 224 are separate parts, and both are made using thin plates (sheet metal) with a thickness of about 0.5 mm to several mm.

<<Exhaust port cover 222>>
The exhaust port cover 222 surrounds the exhaust port 15 (exhaust port 133) and covers almost the entire circumference in the circumferential direction of the exhaust port 15. In other words, the exhaust port cover 222 covers almost the entire circumference (the entire circumferential circumference of the exhaust port 15) so as to surround the exhaust port 15 (exhaust port 133). This exhaust port cover 222 can also be called, for example, an "exhaust port cover".

The exhaust port cover 222 is composed of multiple parts (two parts in this embodiment), a first exhaust port cover part 222A and a second exhaust port cover part 222B. Both exhaust port cover parts 222A, 222B are stainless steel sheet metal parts with a thickness of about 0.5 mm to several mm. However, since both exhaust port cover parts 222A, 222B have a smaller curved area than the side cover 224, it is easy to increase the thickness. Not only does the thickness have an advantage in terms of insulation, but it also makes it easier to deal with (remove, etc.) burrs and edges that occur on the ends when manufacturing by press processing, etc.

Figure 10 (a) shows the second exhaust port cover part 222B out of the two exhaust port cover parts 222A, 222B. The second exhaust port cover part 222B is curved to fit the curved surface of the outer tube 127. Although not shown, the other first exhaust port cover part 222A is also curved to fit the curved surface of the outer tube 127.

The first exhaust port cover part 222A and the second exhaust port cover part 222B are arranged symmetrically with respect to the center line A (shown by a dashed line in FIG. 6). The center line A is parallel to the axis of the turbomolecular pump 100 and passes through the center of the exhaust port 133 when viewed from the front.

The shapes and arrangement of the two exhaust port cover parts 222A, 222B are not limited to being line-symmetric. For example, although not shown in the figures, the balance of the sizes of the two exhaust port cover parts 222A, 222B may be determined so that the center line A passes through one of the two exhaust port cover parts 222A, 222B.

Furthermore, the center line A is not limited to being parallel to the axis of the turbomolecular pump 100. For example, it is also possible to define a center line B that is oriented in a direction that intersects (e.g., perpendicular to) the center line A, and to arrange both exhaust port cover parts 222A and 222B in line symmetry with respect to this center line B.

Both exhaust port cover parts 222A, 222B can be removed even with the side cover 224 attached. By making them removable even with the side cover 224 attached in this way, for example, when attaching an exhaust port heater 226 (described later) to the exhaust port 15, the work becomes easier than when the side cover 224 is also removed or when the entire insulating cover 210 is removed.

For example, as shown in FIG. 5, an exhaust port heater 226 (schematically shown by a two-dot chain line) may be attached to the exhaust port 15 depending on the application of the turbomolecular pump 100. The exhaust port heater 226 is attached to the exhaust port 15 so as to cover the periphery of the exhaust port 15. Furthermore, the exhaust port heater 226 is often attached and removed on-site by the user.

The base end of the exhaust port 15 enters the recess 228 of the outer wall 214, and the base end of the exhaust port heater 226 also reaches the back of the recess 228 of the outer wall 214. When the exhaust port heater 226 is installed, the base end of the exhaust port heater 226 is inserted into the recess 228 of the outer wall 214.

When installing such an exhaust port heater 226, if the insulation cover 210 (here, both exhaust port cover parts 222A, 222B) is left attached, the exhaust port heater 226 may be pushed in while interfering with the insulation covers, which may result in deformation of the insulation covers.

Therefore, by removing both exhaust port cover parts 222A and 222B, a wide field of view for work can be secured. This allows the exhaust port heater 226 to be installed accurately. In addition, the range of work required for removal is small, making removal and reinstallation easier and more efficient than if the entire insulation cover 210 were removed.

Furthermore, in this embodiment, both exhaust port cover parts 222A, 222B are attached to the outer wall 214. Both exhaust port cover parts 222A, 222B are attached using anti-falloff screws 230. Various general anti-falloff screws can be used as the anti-falloff screws 230. In this embodiment, a combination of a cross recessed anti-falloff pan head screw and an anti-falloff washer (not shown) is used.

Although not shown in the figure, the threaded portion of the cross recessed capsizing pan head screw protrudes radially beyond the shaft portion. The cross recessed capsizing pan head screw is screwed in such a way that it sandwiches the first exhaust port cover part 222A (or the second exhaust port cover part 222B) and the capsizing washer. When the cross recessed capsizing pan head screw is loosened, the threaded portion gets caught in the recessed portion of the capsizing washer, preventing the cross recessed capsizing pan head screw from falling off.

As such cross-recessed captive pan head screws and captive washers, it is possible to use those manufactured by Nabeya Bi-Tech Co., Ltd., for example.

Note that the fixing of the exhaust port cover parts 222A and 222B is not limited to screws, and other fixing devices may be used. Examples of fixing devices other than screws include hook-and-loop fasteners (sufficiently heat-resistant).

<<Side cover 224>>
Next, the side cover 224 described above covers the side of the turbo molecular pump 100 except for the area around the exhaust port 15. The side cover 224 and the exhaust port cover 222 cover the side of the turbo molecular pump 100 over approximately 360 degrees.

The side cover 224 is divided into multiple parts (two in this case) in the circumferential direction of the turbomolecular pump 100, and is composed of a first side cover part 224A and a second side cover part 224B. Both side cover parts 224A, 224B are stainless steel sheet metal parts with a thickness of about 0.5 mm to several mm.

Figure 10 (b) shows the second side cover part 224B of the two side cover parts 224A, 224B. The second side cover part 224B is curved along the curved surfaces of the outer wall 214, the water-cooled spacer 125d, and the base part 129. Although not shown, the other first side cover part 224A is similarly curved along the curved surfaces of the outer wall 214, the water-cooled spacer 125d, and the base part 129.

In this embodiment, the side cover parts 224A and 224B are attached to the outer wall 214. The side cover parts 224A and 224B are also attached using anti-falloff screws 230. As with the exhaust port cover parts 222A and 222B, various general anti-falloff screws can be used for the anti-falloff screws 230.

<<Reducing the Surface Temperature of the Exhaust Port Cover 222 and the Side Cover 224>>
As described above, the exhaust port cover 222 and the side cover 224 are fixed to the outer wall 214. A gap 216 is provided between the outer wall 214 and the heater spacer 212. In addition, a heat insulator washer 220 is provided between the outer wall 214 and the water-cooled spacer 125d.

As mentioned above, the temperature of the heater spacer 212 may reach over 150°C, and the temperature of the rotor 102 (e.g., rotor 102e, 102f) on the exhaust port 15 side (base portion 129 side, downstream side) and the fixed blade 123 (e.g., fixed blade 123e, 123f) may reach, for example, approximately 100°C.

In such a temperature environment, the surface temperatures of the exhaust port cover 222 and the side cover 224 were measured and found to be kept below 65°C. This is because, in the turbomolecular pump 100 of this embodiment, the outer wall 214 to which the exhaust port cover 222 and the side cover 224 contact is temperature-adjusted against the heat inside the casing 215. This is also because the heat insulator washer 220 and the gap 221 are interposed between the outer wall 214 and the water-cooled spacer 125d.

<<Measures to improve strength of side cover 224>>
Strengthening measures are taken for the side cover 224. In this embodiment, sheet metal bending is adopted as the strength enhancing measure. The strength enhancing measure is intended to reduce deformation of the side cover 224.

As shown in FIG. 10(b), a bent structure is adopted for one end of the second side cover part 224B in the longitudinal direction (circumferential direction of the turbo molecular pump 100). The bent structure is formed by bending the end of the second side cover part 224B inward (toward the inner circumferential surface) by a width of about several millimeters (e.g., 5 mm) to provide a bent portion 232B.

As shown in FIG. 6, the second side cover part 224B is attached to the outer wall 214 with the folded portion 232B facing the second exhaust port cover part 222B.

A similar structure is used for the first side cover part 224A. As shown in FIG. 6, the first side cover part 224A is attached to the outer wall 214 with the bent portion 232A facing the first exhaust port cover part 222A.

By providing such bent portions 232A, 232B, the rigidity of one end of both side cover parts 224A, 224B is increased, improving the strength of the side cover 224. In addition, the bent portions 232A, 232B can fill the gap between the end of the first side cover part 224A and the recess 228 of the outer wall 214, and the gap between the end of the second side cover part 224B and the recess 228 of the outer wall 214, over the width C of the bent portions 232A, 232B (shown for bent portion 232B in FIG. 10(b)).

If such strength-improving measures are not taken, for example, if an excessive load or impact is applied from the outside to the boundary between the side cover parts 224A, 224B and the exhaust port cover parts 222A, 222B, the side cover parts 224A, 224B and the exhaust port cover parts 222A, 222B may deform. Furthermore, the gaps 234A, 234B (Figure 6) may widen to, for example, about 10 mm, which may allow the entry of an operator's fingers, tools, etc.

The area around the exhaust port 15 is prone to high temperatures, and if fingers or tools enter the gaps 234A and 234B, the fingers or tools may come into contact with hot areas. In addition, the heater spacer 212 is surrounded by lead wires 148a for the heater 148 and has electrical terminals, so fingers may come into contact with these electrical system components. Therefore, it is important to prevent fingers or tools from entering the gaps 234A and 234B.

By taking the above-mentioned strength improvement measures, both side cover parts 224A, 224B are reinforced, and the rigidity of the ends of both side cover parts 224A, 224B is improved. This makes it possible to prevent deformation of both side cover parts 224A, 224B and to prevent the gaps 234A, 234B from expanding. This also makes it possible to prevent the worker's fingers or tools from entering the gaps 234A, 234B.

In addition, when considering not only rigidity but also thermal insulation, it is desirable not to increase the area of the portions of the side cover parts 224A, 224B that come into contact with the outer wall 214. For this reason, for example, the relationship between the bent portions 232A, 232B and the recessed portion 228 of the outer wall 214 is set to a degree that the width C of the bent portions 232A, 232B (shown for the bent portion 232B in FIG. 10(b)) fits within the recessed portion 228 of the outer wall 214.

By doing this, the bent portions 232A, 232B can be prevented from contacting the outer wall 214, and the area of the portions of the side cover parts 224A, 224B that contact the outer wall 214 can be prevented from increasing.

Although not shown in the figures, it is possible to provide bent portions (e.g., similar to bent portions 232A, 232B) at the ends 236A, 236B of the side cover parts 224A, 224B that face each other. In this case, even if an impact is applied to the ends 236A, 236B of the side cover parts 224A, 224B, deformation of the side cover parts 224A, 224B is prevented.

The above-mentioned strength improvement measures can be applied not only to the side cover parts 224A and 224B, but also to the exhaust port cover parts 222A and 222B. Although not shown in the figures, it is possible to form bent parts (e.g., similar to bent parts 232A and 232B) in the exhaust port cover parts 222A and 222B.

Furthermore, the strength improvement measures are not limited to bending the metal plate. For example, as a strength improvement measure, it is possible to install a support member 238 as shown in a modified example (which may be a second embodiment) in FIG. 11. In the turbomolecular pump 260 of the type shown in FIG. 11, a gap 242 is formed between the exhaust port cover 222 and the outer wall 214. A gap 244 is also formed between the side cover 224 and the outer wall 214.

Support members 238 are installed in these gaps 242, 244. Multiple support members 238 (e.g., eight) are installed around the outer wall 214. The cross-sectional shape of the support members 238 is, for example, a perfect cylinder (collar-shaped or sleeve-shaped).

In the example of FIG. 11, the shaft of the anti-fall-off screw 230 is passed through the support member 238, and the support member 238 surrounds the entire circumference of the shaft of the anti-fall-off screw 230. One axial end of the support member 238 contacts the outer wall 214, and the other end contacts both exhaust port cover parts 222A, 222B and both side cover parts 224A, 224B.

By providing such a support member 238, when there is a gap 242 between the exhaust port cover 222 and the outer wall 214, or a gap 244 between the side cover 224 and the outer wall 214, the exhaust port cover 222 and the side cover 224 do not simply float relative to the outer wall 214, but can be reinforced. This prevents the exhaust port cover 222 and the side cover 224 from deforming and widening the gap to a level that would allow an operator's fingers or tools to enter.

In the turbomolecular pump 260 of FIG. 11, not only are the strength-improving measures as described above taken, but insulation is also provided by support members 238 and the like. This type omits the heat insulator washer 220 in the turbomolecular pump 100 of the example of FIG. 5, and instead has gaps 242, 244 between the outer wall 214 and the exhaust port cover 222 and the side cover 224. The turbomolecular pump 260 of FIG. 11 suppresses temperature rise in the exhaust port cover 222 and the side cover 224 by forming the gaps 242, 244.

In addition, in the example of FIG. 11, the support member 238 is in contact with the outer wall 214, the exhaust port cover 222, and the side cover 224. Therefore, the support member 238 not only functions as a reinforcing material, but also as a heat insulator. The support member 238 can prevent heat from being transferred from the outer wall 214 to the exhaust port cover 222 and the side cover 224.

The configuration shown in FIG. 11 is more suitable for turbomolecular pumps in which the outer wall 214 is more likely to reach high temperatures than the configuration shown in FIG. 5.

In the example shown in FIG. 11, the support member 238 is cylindrical, and is fixed via the anti-falloff screw 230. However, this is not limited to this, and for example, the support member 238 can be a solid rod-shaped member. In this case, although not shown in the figure, the support member 238 can be fixed by various general methods.

For example, male threads are formed on both axial ends of the support member 238. One male threaded portion is then screwed into the outer wall 214 and connected to the outer wall 214. The other male threaded portion is then passed through holes in the exhaust port cover parts 222A, 222B and the side cover parts 224A, 224B, and is fixed to the exhaust port cover parts 222A, 222B and the side cover parts 224A, 224B by tightening nuts from the outside.

<<Other benefits of the turbomolecular pumps 100 and 260>>
In addition to the advantages described above, the turbomolecular pump 100 of this embodiment (FIG. 5, etc.) and the modified turbomolecular pump 260 (FIG. 11) have the following advantages: for example, the outer wall 214 is not a metal plate component but a machined component, so that it is easy to chamfer the edge of the step with a large radius of curvature (R). This makes it easy to ensure safety when the user's fingers touch the edge of the outer wall 214.
<<Inventions that can be extracted from this embodiment>>

The following inventions can be extracted from the above-described embodiment.
(1) a casing (e.g., a casing 215 including an outer cylinder 127, an outer wall 214, and a heater spacer 212) in which at least one of an intake port (e.g., intake port 101) and an exhaust port (e.g., exhaust port 133) is provided;
a heating means (such as a heater 148) for heating at least a part of the casing and the exhaust port to a high temperature;
A vacuum pump (such as turbomolecular pump 100) comprising:
The vacuum pump is
An annular, thin-plate-shaped side cover (such as side cover 224) that covers a side surface of the casing;
A thin plate-shaped exhaust port cover (such as exhaust port cover 222) that covers the periphery of the exhaust port;
having
The vacuum pump according to claim 1, wherein the exhaust port cover is a separate part from the side cover and can be detached even when the side cover is attached.
(2) The vacuum pump according to (1) above, characterized in that the exhaust port cover substantially completely surrounds the periphery of the exhaust port and is composed of at least two parts.
(3) The vacuum pump according to (2) above, wherein the exhaust port cover has a structure divided symmetrically with respect to a center line (such as center line A) passing through the center of the exhaust port.
(4) A gap (gap 242, 244, etc.) is provided between the side cover or the exhaust port cover and the casing,
The vacuum pump described in (1) above, characterized in that strength improvement measures (such as providing bent portions 232A, 232B, providing support members 238, etc.) are taken in the gap to reduce deformation of the side cover or the exhaust port cover.
(5) The vacuum pump described in (4) above, wherein the strength improving measure is a structure in which at least one end of the side cover or the exhaust port cover is bent toward the casing (such as a structure provided with bent portions 232A, 232B).
(6) The vacuum pump according to (4) above, wherein the strength improving measure uses a support structure (such as a structure provided with a support member 238) arranged between the casing and the side cover or the exhaust port cover.
(7) A vacuum pump described in any one of (1) to (6) above, characterized in that the portion of the casing in which the side cover or the exhaust port cover is arranged is temperature-controlled by a temperature control means (such as a heater 148).
(8) A vacuum pump according to any one of (1) to (6) above, characterized in that the casing is formed in a double structure of an inner casing (such as the heater spacer 212) which is a structure for ensuring a vacuum in an exhaust flow path within the vacuum pump, and an outer casing (such as the outer wall 214) which surrounds the inner casing.

The present invention is not limited to the above-described embodiments, and various modifications and combinations of the embodiments are possible without departing from the spirit of the present invention.

15: exhaust port 100, 260: turbo molecular pump 101: intake port 102: rotor 103: rotor 123: stator 125: stator spacer 125d: water-cooled spacer 133: exhaust port 148: heater 148a: lead wire 149: water-cooled pipe 210: heat insulating cover 212: heater spacer 214: outer wall 215: casing 216: gap 218: water-cooled pipe 220: heat insulator washer 222: exhaust port cover 222A: first exhaust port cover part 222B: second exhaust port cover part 224: side cover 224A: first side cover part 224B: second side cover part 226: exhaust port heater 228: recess 230: fall prevention screw 232A, 232B : Bent portions 234A, 234B : Gap 238 : Support members 242, 244 : Void

Claims (8)

a casing provided with at least the exhaust port among an intake port and an exhaust port;
a heating means for heating at least a part of the casing and the exhaust port to a high temperature;
A vacuum pump comprising:
The vacuum pump is
a ring-shaped thin plate-shaped side cover that covers a side surface of the casing;
A thin plate-shaped exhaust port cover that covers the periphery of the exhaust port;
having
The vacuum pump according to claim 1, wherein the exhaust port cover is a separate part from the side cover and can be detached even when the side cover is attached. The vacuum pump according to claim 1, characterized in that the exhaust port cover covers almost the entire circumference of the exhaust port and is composed of at least two parts. The vacuum pump according to claim 2, characterized in that the exhaust port cover is divided symmetrically with respect to a center line passing through the center of the exhaust port. a gap is provided between the side cover or the exhaust port cover and the casing;
2. The vacuum pump according to claim 1, wherein a strength improving measure is implemented in the gap to reduce deformation of the side cover or the exhaust port cover. The vacuum pump according to claim 4, characterized in that the strength-improving measures are implemented by using a structure in which at least one end of the side cover or the exhaust port cover is bent toward the casing. The vacuum pump according to claim 4, characterized in that the strength improvement measures are implemented by using a support structure arranged between the casing and the side cover or the exhaust port cover. A vacuum pump according to any one of claims 1 to 6, characterized in that the temperature of the portion of the casing where the side cover or the exhaust port cover is disposed is controlled by a temperature control means. 7. The vacuum pump according to claim 1, wherein the casing is formed in a double structure of an inner casing which is a structure for ensuring a vacuum in an exhaust flow path within the vacuum pump, and an outer casing which surrounds the inner casing.