JP7652576B2 - Vacuum pump and spacer - Google Patents

Description

The present invention relates to a vacuum pump and a spacer used in the vacuum pump.

Vacuum pumps such as turbomolecular pumps are used to evacuate the inside of vacuum chambers installed in semiconductor manufacturing equipment. The semiconductor manufacturing process includes a step in which various process gases are applied to the semiconductor substrate, and vacuum pumps are used not only to create a vacuum inside the chamber of the semiconductor device, but also to evacuate the process gas from inside the chamber.

When a process gas flows through a flow passage in a vacuum pump, the process gas solidifies and accumulates on the inner wall surface of the flow passage at the point where the pressure-temperature relationship shown in the vapor pressure curve changes from gas phase to solid phase. For example, in a vacuum pump that has a turbomolecular pump mechanism consisting of a fixed blade and a rotor on the intake side, and a threaded pump mechanism consisting of a cylindrical part of a rotor and a threaded spacer on the exhaust side, the pressure of the process gas increases in the threaded pump mechanism. As a result, solidified products accumulate on the walls of the flow passage, especially on the exhaust side, and the performance of the pump may decrease.

To address this issue, a conventional approach has been to use a heating source such as a heater to heat the exhaust side periphery of the vacuum pump, thereby increasing the temperature of the process gas in the exhaust side flow path, thereby suppressing the deposition of products.

However, the heat from the above heating source is also transferred to the fixed vanes adjacent to the exhaust side periphery and the fixed vane spacers (hereinafter sometimes referred to as spacers) that hold the fixed vanes in place, so extra energy is required to heat the process gas.

In addition, if the temperature of the rotor rises due to frictional heat with the gas it comes into contact with, there is a risk that creep will cause the rotor's durability to be compromised, so it is essential to suppress the temperature rise by dissipating heat to the fixed blades through radiation, etc. However, if the temperature of the fixed blades or fixed blade spacers rises due to heat from the heat source, heat cannot be dissipated efficiently from the rotor to the fixed blades, and there is a risk that the temperature of the rotor will rise too high.

In order to solve these problems, a vacuum pump has been proposed in Patent Document 1. This vacuum pump has multiple heat insulating members intermittently arranged in the circumferential direction at the connection between an upper casing that covers the outer periphery of the turbo molecular pump mechanism and an intermediate casing that is connected to the upper casing and has a heater installed therein, thereby suppressing the temperature of the fixed blades by preventing the heat from the heater from being transmitted to the fixed blades via the upper casing.

JP 2006-37951 A

On the other hand, the vacuum pump in Patent Document 1 requires separate insulating materials, which increases parts costs. In addition, the number of assembly steps increases with the increase in the number of parts, which increases manufacturing costs.

In view of these circumstances, the present invention aims to provide a vacuum pump that can suppress the temperature rise of the fixed blades due to heat from a heating source without increasing the number of parts, and a spacer for use in such a vacuum pump.

The present invention relates to a vacuum pump comprising a casing, a rotating shaft supported rotatably inside the casing, a plurality of rotors arranged in multiple stages on the outer periphery of the rotating shaft and rotating together with the rotating shaft, a plurality of stationary blades arranged in multiple stages between the rotors, a plurality of spacers arranged in multiple stages inside the casing and holding the stationary blades in predetermined positions, and a heater provided on the exhaust side of the plurality of spacers , wherein the plurality of spacers that hold the stationary blades have one surface that contacts an intake side surface of the stationary blade and another surface that contacts an exhaust side surface of the stationary blade located on the one-stage intake side, and at least one spacer among the plurality of spacers that hold the stationary blades has a heater that is disposed on the exhaust side of the stationary blade. the first surface has a concave surface, the first surface is provided with a second positioning portion that protrudes from an outer edge of the first surface toward the exhaust side and is inserted into the outer peripheral surface of the fixed wing with which the first surface comes into contact, the other surface is provided with a first positioning portion that is a portion of the outer edge of the other surface that is concave toward the exhaust side and opens to the outer peripheral side, the first positioning portion engages with the second positioning portion of the spacer located on the first-stage intake side, the spacer having the concave surface is made by cutting from an extruded material, the first surface and the other surface, the concave surface, the second positioning portion, and the first positioning portion are machined portions, and the other surface is a surface that does not have a recess except for the first positioning portion .

It is also preferable that the spacer located closest to the exhaust side among the multiple spacers has the concave surface.

Here, the wrought material is preferably an aluminum alloy.

The present invention also relates to a vacuum pump including a casing, a rotating shaft supported rotatably inside the casing, a plurality of rotors arranged in multiple stages on the outer periphery of the rotating shaft and rotating together with the rotating shaft, and a plurality of fixed blades arranged in multiple stages between the rotors, the spacers being arranged in multiple stages inside the casing and holding the fixed blades in predetermined positions, the vacuum pump including a heater provided on the exhaust side of the plurality of spacers, the plurality of spacers holding the fixed blades each having one surface that contacts an intake side surface of the fixed blade and another surface that contacts an exhaust side surface of the fixed blade located on the one-stage intake side, and at least one of the plurality of spacers holding the fixed blades Each spacer has a concave surface on one side , and a second positioning portion is provided on the one side which protrudes from the outer edge of the one side toward the exhaust side and is inserted into the outer peripheral surface of the fixed wing with which the one side comes into contact, and a first positioning portion is provided on the other side, where the outer edge of the other side is recessed toward the exhaust side and opens to the outer peripheral side, and the second positioning portion of the spacer located on the first-stage intake side engages with the first positioning portion, and the spacer having the concave surface is made by cutting from an extruded material, and the one side and the other side, the concave surface, the second positioning portion, and the first positioning portion are machined portions, and the other side is a surface that does not have a recess except for the first positioning portion .

In the vacuum pump of the present invention, the spacer that holds the fixed blades in place has a concave surface on the contact surface that comes into contact with the fixed blades, which reduces the contact area with the fixed blades and increases the thermal resistance at the contact surface, thereby suppressing the transfer of heat between the spacer and the fixed blades and suppressing the rise in temperature of the fixed blades. In addition, the provision of a concave surface narrows the thermal path of the spacer and prevents the transfer of heat, making it possible to suppress a drop in temperature in areas where it is desired to maintain a certain temperature, such as the threaded pump mechanism.

1 is a vertical cross-sectional view that shows a schematic diagram of an embodiment of a vacuum pump according to the present invention. FIG. 2 is a circuit diagram of an amplifier circuit of the vacuum pump shown in FIG. 1 . 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. 2 is a partial enlarged view of a portion A shown in FIG. 1 and a partial enlarged view of a spacer. 13A and 13B are diagrams showing modified examples of the spacer. 7A to 7C are diagrams relating to a method of manufacturing the spacer shown in FIG. 6. 6A to 6C are diagrams relating to a method of manufacturing the spacer shown in FIG. 5 .

The turbomolecular pump 100, which is one embodiment of a vacuum pump according to the present invention, will now be described with reference to the drawings. First, the overall configuration of the turbomolecular pump 100 will be described with reference to Figs. 1 to 4. Note that the "casing" according to the present invention described above, in the turbomolecular pump 100 of this embodiment, is composed of a main casing portion 114 equipped with an outer cylinder 127, and a base portion 129. Also, in this embodiment, the "rotating shaft" according to the present invention is composed of a rotating body 103 and a rotor shaft 113, which will be described below.

A longitudinal cross-sectional view of this turbomolecular pump 100 is shown in FIG. 1. In FIG. 1, the turbomolecular pump 100 is provided with an intake port 101 at the upper end of a cylindrical outer tube 127. Inside the outer tube 127, a rotor 103 is provided, with multiple rotors 102 (102a, 102b, 102c, ...) which are turbine blades for sucking in and exhausting gas, formed radially around the periphery in multiple stages. A rotor shaft 113 is attached to the center of this rotor 103, and this rotor shaft 113 is supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing. The rotor 103 is generally made of a metal such as aluminum or an aluminum alloy.

The upper radial electromagnets 104 are arranged in pairs on the X-axis and Y-axis. Four upper radial sensors 107 are provided in close proximity 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.

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, axial electromagnets 106A and 106B are arranged above and below a circular metal disk 111 provided at the bottom of rotor shaft 113. Metal disk 111 is made of a high magnetic permeability material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and the axial position signal is sent to 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.

Furthermore, for example, a phase sensor (not shown) is attached 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 pole.

Multiple fixed blades 123 (123a, 123b, 123c...) are arranged with a small gap 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 (123a, 123b, 123c...) are made of metals such as aluminum, iron, stainless steel, copper, etc., or alloys containing these metals as components.

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 as components. 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 131a engraved on its inner peripheral surface. The helical direction of the thread groove 131a 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. A cylindrical part 102d hangs down from the lowest part of the rotor 103, which is connected to the rotor vanes 102 (102a, 102b, 102c, ...). The outer peripheral surface of this cylindrical part 102d 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 predetermined gap therebetween. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blade 123 is guided by the thread groove 131a and sent to the base portion 129.

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 rotation speed of the rotor 102 is usually 20,000 rpm to 90,000 rpm, and the peripheral speed at the tip of the rotor 102 reaches 200 m/s to 400 m/s. The exhaust gas drawn in from the intake port 101 passes between the rotor 102 and the fixed blades 123 and is transferred to the base part 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 conduction of heat generated by the motor 121, but this heat is transferred to the fixed blades 123 side by radiation or conduction by gas molecules of the exhaust gas.

The fixed blade spacers 125 are joined together at their outer peripheries and transmit 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 to the main casing portion 114. In this embodiment, a ring-shaped water-cooled pipe 115 is wrapped around the outer periphery of the upper portion of the outer cylinder 127 to efficiently dissipate the heat transmitted to the main casing portion 114.

In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotor 103, and the thread groove 131a is engraved on the inner periphery of the threaded spacer 131. However, there are also cases where the opposite is true, that is, a thread groove is engraved on the outer periphery of the cylindrical portion 102d, 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, 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, may be covered with a stator column 122 and a predetermined pressure may be maintained inside the stator column 122 with purge gas to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section.

In this case, piping (not shown) is provided in the base portion 129, and purge gas is introduced through this piping. The introduced purge gas is sent to the exhaust port 133 through the gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102.

The turbomolecular pump 100 requires control based on the model identification and individually adjusted unique parameters (for example, various characteristics corresponding to the model). To store these control parameters, the turbomolecular pump 100 has an electronic circuit section 141 in its main body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown) 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 the 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 the process gas in an Al etching device, the vapor pressure curve shows that at low vacuum (760 torr to 10-2 torr) and low temperature (approximately 20°C), solid products (e.g. AlCl3) precipitate and deposit inside the turbomolecular pump 100. As a result, when process gas deposits 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 aforementioned products are prone to solidification and adhesion in areas of high pressure near the exhaust port 133 and near the threaded spacer 131.

Therefore, in order to solve this problem, conventionally, a heater 116 is placed around the outer circumference of the main body casing 114 or base 129, etc., and a circular water-cooled tube 115 or water-cooled tube 149 is wrapped around it. In addition, a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base 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 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 150 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 of the rotation speed, 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.

That is, 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.

Next, the above-mentioned fixed vane spacers 125 (125a, 125b, 125c, etc.) will be described in detail with reference to Figures 1 and 5. The turbomolecular pump 100 of this embodiment includes first fixed vane spacers 125a, 125b, and 125c, and second fixed vane spacers 125d and 125e as the fixed vane spacers 125.

As shown in Figures 1 and 5, the first fixed wing spacers 125a, 125b, and 125c are ring-shaped members centered on the central axis CA. The first fixed wing spacers 125a, 125b, and 125c have flat upper surfaces 125a1, 125b1, and 125c1 extending horizontally. The outer edges of the upper surfaces 125a1, 125b1, and 125c1 are provided with first positioning portions 125a2, 125b2, and 125c2 that are recessed downward. The first fixed wing spacers 125a, 125b, and 125c also have flat lower surfaces 125a3, 125b3, and 125c3 that extend parallel to the upper surfaces 125a1, 125b1, and 125c1. Second positioning portions 125a5, 125b5, and 125c5 that protrude downward are provided on the outer edges of the lower surfaces 125a3, 125b3, and 125c3.

As shown in Figures 1 and 5, the second fixed wing spacer 125d, 125e is also a ring-shaped member centered on the central axis CA, and has a flat upper surface 125d1, 125e1 extending horizontally, and a first positioning portion 125d2, 125e2 provided on the outer edge of the upper surface 125d1, 125e1 and having a shape recessed downward. The second fixed wing spacer 125d, 125e also has a lower surface 125d3, 125e3 extending parallel to the upper surface 125d1, 125e1, and the lower surface 125d3, 125e3 has a concave surface 125d4, 125e4 that is recessed upward from the lower surface 125d3, 125e3. The outer edge of the lower surface 125d3, 125e3 is provided with a second positioning portion 125d5, 125e5 that protrudes downward.

The first fixed wing spacers 125a, 125b, 125c and the second fixed wing spacers 125d, 125e having such a configuration are arranged in multiple stages in the order of the first fixed wing spacers 125a, 125b, 125c, the second fixed wing spacers 125d, 125e from top to bottom (from the intake port 101 side to the exhaust port 133 side) inside the outer tube 127 between the overhanging portion 114a provided on the upper part of the main body casing portion 114 and the threaded spacer 131, as shown in Figures 1 and 5. At this time, the outer peripheral ends of the fixed wing 123 (123a, 123b, 123c...) are inserted between the stacked fixed wing spacers 125. Here, the lower surfaces 125a3, 125b3, 125c3, 125d3, 125e3 of the first fixed wing spacer 125a etc. contact the upper surface of the outer circumferential end of the fixed wing 123 (123a, 123b, 123c, ...), and the upper surfaces 125b1, 125c1, 125d1, 125e1 of the first fixed wing spacer 125b etc. or the upper surface of the threaded spacer 131 contact the lower surface of the outer circumferential end of the fixed wing 123, so that the fixed wing 123 is clamped. That is, the fixed wing 123 is held at a predetermined position in the vertical direction by the first fixed wing spacer 125a etc. Also, the outer circumferential surface of the fixed wing 123 contacts the inner circumferential surface of the second positioning parts 125a5, 125b5, 125c5, 125d5, 125e5 of the first fixed wing spacer 125a etc. Here, the inner circumferential surfaces of the second positioning portions 125a5, 125b5, 125c5, 125d5, and 125e5 are also in contact with the inner circumferential surfaces of the first positioning portions 125a2, 125b2, 125c2, 125d2, and 125e2. That is, the fixed wing 123 (123a, 123b, 123c, etc.) is held at a predetermined position in the radial direction by the first fixed wing spacer 125a, etc.

In this embodiment, in order to suppress deposition of precipitates on the threaded spacer 131, the threaded spacer 131 is provided with a heater 116, and the threaded spacer 131 is heated. This heat is also transmitted to the lowest fixed blade 123e that contacts the threaded spacer 131. As a structure for heating the threaded spacer 131, the heater 116 may be provided on the base portion 129 as described above.
On the other hand, a concave surface 125e4 is provided on the lower surface 125e3 of the second fixed wing spacer 125e that contacts the lowest fixed wing 123e. That is, the contact area between the fixed wing 123 and the second fixed wing spacer 125e is reduced, and the thermal resistance at the contact surface is increased, so that the transfer of heat from the lowest fixed wing 123e to the second fixed wing spacer 125e can be suppressed, and the temperature rise of the fixed wing 123 (123a, 123b, 123c, ...) above the lowest stage can be suppressed. In addition, the provision of the concave surface 125e4 narrows the thermal path of the second fixed wing spacer 125e, so that the transfer of heat from the threaded spacer 131 is hindered, and the temperature drop of the threaded spacer 131 can be suppressed.

In this embodiment, the second fixed wing spacer 125d, which is located one step above the second fixed wing spacer 125e, also has a concave surface 125d4 on its lower surface 125d3. Therefore, the temperature rise of the fixed wing 123 and the temperature drop of the threaded spacer 131 can be more effectively suppressed.

In this embodiment, there are two second fixed wing spacers 125d, 125e, but there may be one or three or more. The position of the second fixed wing spacers 125d... is not limited to the illustrated example, and they may be arranged, for example, in the second row, the third row, etc. from the bottom. It is more preferable to arrange the second fixed wing spacer 125e in the bottom row as in this embodiment, because the number of fixed wings 123 that can suppress temperature rise increases, and the temperature rise of the rotor 102 (102a, 102b, 102c...) can be effectively suppressed.

The second fixed wing spacers 125d and 125e described above have concave surfaces 125d4 and 125e4 on the lower surfaces 125d3 and 125e3, but as in the second fixed wing spacers 125d and 125e shown in FIG. 6, concave surfaces 125d4 and 125e4 may be provided on the upper surfaces 125d1 and 125e1.

The second fixed wing spacers 125d and 125e can be formed by casting or by cutting a wrought material. When forming the second fixed wing spacers 125d and 125e by cutting a wrought material, it is preferable to provide the concave surfaces 125d4 and 125e4 on the lower surfaces 125d3 and 125e3 of the second fixed wing spacers 125d and 125e. This will be explained with reference to Figures 7 and 8.

7 shows a case where the concave surfaces 125d4, 125e4 are provided on the upper surfaces 125d1, 125e1 when forming the second fixed wing spacers 125d, 125e by cutting the wrought material. Here, the wrought material is a pipe material P that is cylindrical. There is no particular limitation on the material of the wrought material, but considering the ease of processing when making the wrought material into a cylindrical shape and the ease of subsequent cutting, it is preferable to use an aluminum alloy. When forming the second fixed wing spacers 125d, 125e from such a pipe material P, as shown in the figure, one end of the pipe material P is held by a chuck C or the like, and the hatched h1 and h2 parts at the other end are cut by a cutting tool T. Then, the other end of the pipe material P is cut along the line L by the cutting tool T, and the h3 part is cut from the cut part by the cutting tool T. In other words, when cutting the h3 part, it is necessary to hold the cut part again by a chuck C or the like.

On the other hand, when providing the concave surfaces 125d4, 125e4 on the lower surfaces 125d3, 125e3 of the second fixed wing spacers 125d, 125e, as shown in FIG. 8, one end of the pipe material P is held by a chuck C or the like, and then the hatched h4 and h5 parts at the other end are cut with a cutting tool T. The other end of the pipe material P is then cut off along line L to form the second fixed wing spacers 125d, 125e. In other words, when providing the concave surfaces 125d4, 125e4 on the lower surfaces 125d3, 125e3, re-holding by a chuck C or the like is not necessary, simplifying the manufacturing process, thereby shortening the processing time and reducing costs.

Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the spirit of the present invention described in the claims unless otherwise specifically limited in the above description. Furthermore, the effects in the above embodiment are merely examples of the effects resulting from the present invention, and do not mean that the effects of the present invention are limited to the above effects.

100: Turbo molecular pump (vacuum pump)
102: Rotor 103: Rotor (rotating shaft)
113: Rotor shaft (rotating shaft)
114: Main body casing part (casing)
123: Fixed wing 125: Fixed wing spacer (spacer)
125d1, 125e1: Top surface (contact surface)
125d3, 125e3: Bottom surface (contact surface)
125d4, 125e4: concave surface 129: base portion (casing)

Claims (4)

A casing;
A rotating shaft rotatably supported inside the casing;
A plurality of rotors provided in multiple stages on an outer periphery of the rotary shaft and rotating together with the rotary shaft;
A plurality of stator blades arranged in multiple stages between the rotor blades;
a plurality of spacers provided in multiple stages inside the casing and holding the stator blades in predetermined positions;
a heater provided on an exhaust side of the plurality of spacers ,
the spacers for holding the fixed vanes each have one surface contacting an intake side surface of the fixed vane and another surface contacting an exhaust side surface of the fixed vane located on the first stage intake side,
At least one of the spacers that hold the stator blades has a concave surface on the one surface ,
a second positioning portion is provided on the one surface, protruding from an outer edge portion of the one surface to an exhaust side and fitted into an outer circumferential surface of the fixed blade with which the one surface comes into contact;
The other surface is provided with a first positioning portion, the first positioning portion being a portion in which an outer edge of the other surface is recessed toward the exhaust side and opens toward an outer circumferential side, and the second positioning portion of the spacer located on the first stage intake side engages with the first positioning portion,
A vacuum pump characterized in that the spacer having the concave surface is made by cutting a wrought material, the one surface and the other surface, the concave surface, the second positioning portion, and the first positioning portion are machined portions, and the other surface is a surface that does not have a recess except for the first positioning portion . 2. The vacuum pump according to claim 1 , wherein the spacer located closest to the exhaust side among the plurality of spacers has the concave surface. 2. A vacuum pump according to claim 1 , wherein the wrought material is an aluminum alloy. A casing;
A rotating shaft rotatably supported inside the casing;
A plurality of rotors provided in multiple stages on an outer periphery of the rotary shaft and rotating together with the rotary shaft;
a plurality of stator vanes arranged in multiple stages between the rotor vanes, the spacer being provided in multiple stages inside the casing and holding the stator vanes in predetermined positions,
the vacuum pump includes a heater provided on an exhaust side of the plurality of spacers;
the spacers for holding the fixed vanes each have one surface contacting an intake side surface of the fixed vane and another surface contacting an exhaust side surface of the fixed vane located on the first stage intake side,
At least one of the spacers that hold the stator blades has a concave surface on the one surface ,
a second positioning portion is provided on the one surface, protruding from an outer edge portion of the one surface to an exhaust side and fitted into an outer circumferential surface of the fixed blade with which the one surface comes into contact;
The other surface is provided with a first positioning portion, the first positioning portion being a portion in which an outer edge of the other surface is recessed toward the exhaust side and opens toward an outer circumferential side, and the second positioning portion of the spacer located on the first stage intake side engages with the first positioning portion,
The spacer having the concave surface is made by cutting a wrought material, and the one surface and the other surface, the concave surface, the second positioning portion, and the first positioning portion are machined portions, and the other surface is a surface that does not have a recess except for the first positioning portion .

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