Vacuum pump and inflow guide part used in said vacuum pump

Abstract

To provide a sigburn air discharge mechanism which improves a back pressure dependency while suppressing reduction in air discharge speed.SOLUTION: A vacuum pump includes: a casing having an air inlet port; a rotor shaft provided inside the casing; one or more rotational disks which can rotate with the rotor shaft; and one or more fixed disks provided facing an axial direction with respect to each of the one or more rotational disks, and having a facing face on which a spiral grooves having a recess and projection is provided. A gas flow path is formed by the spiral groove facing the one or more rotational disks, and an interaction between the one or more rotational disks and the one or more fixed disks allows the gas introduced from the air inlet port to be discharged. An inflow guide part for guiding a flow of the gas is provided on the air inlet port side from the first rotational disk on the air inlet port side among the one or more rotational disks.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The present invention relates to a vacuum pump and an inflow guide component for use in the vacuum pump. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2015-102076 (Patent Document 1) is a background art in this technical field. This publication states, "A vacuum pump according to an embodiment of the present invention is a composite vacuum pump equipped with a vacuum pump component that effectively connects ducts having an exhaust function and a Siegbahn-type exhaust mechanism. The fixed disk has a spiral groove (helical groove) with peaks and valleys formed therein, and has a protrusion (projection) on either or both of its inner diameter portion, which faces the rotating cylinder (rotating body cylindrical portion), and the inner diameter side of the fixed cylinder disposed on the outer circumference side. The rotating disk also has a spiral groove (helical groove) with peaks and valleys formed therein, and has a protrusion (projection) on either or both of its outer diameter portion, which faces the spacer, and the outer diameter side of the rotating disk" (see Abstract). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-102076 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned Patent Document 1 discloses a configuration in which a protrusion is provided in a return flow path of a Siegbahn type (also called Sigbahn) molecular pump to connect a conduit on the intake side, which has an exhaust function, with a conduit on the exhaust side. Patent Document 1 states that such a configuration can improve exhaust efficiency.

[0005] It is known that this Sigburn pumping mechanism has excellent back-pressure dependency, and that this can be improved, for example, by combining it with other pumping mechanisms or by increasing the number of stages. This "back-pressure dependency" is an index that represents the degree of influence that back-pressure (pressure at the exhaust port) has on suction pressure (pressure at the intake port) in a vacuum pumping system; the lower this degree of influence, the better the back-pressure dependency. However, in the Sigburn pumping mechanism, there is a trade-off: as back-pressure dependency improves, the pumping speed decreases. [Means for solving the problem]

[0006] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes a plurality of means for solving the above problems, and examples thereof include: a casing having an intake port; a rotor shaft disposed within the casing; one or more rotating disks rotatable together with the rotor shaft; one or more fixed disks arranged axially opposite each of the one or more rotary disks, and each having a spiral groove with a valley portion and a peak portion on the opposing surface; Equipped with a gas flow path is formed by the spiral groove facing the one or more rotating disks; A vacuum pump that exhausts gas introduced from the inlet by interaction between the one or more rotating disks and the one or more fixed disks, The gas inlet passage is characterized in that an inflow guide portion for guiding the inflow of the gas is provided on the inlet port side of a first rotating disk on the inlet port side among the one or more rotating disks. [Effects of the Invention]

[0007] According to the present invention, in a Sigbahn type exhaust mechanism, it is possible to improve the back pressure dependency while suppressing a decrease in exhaust speed. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an example of a vertical cross-sectional view of a turbomolecular pump. [Figure 2] FIG. 2 is an example of a circuit diagram of an amplifier circuit for controlling the rotor shaft of a turbomolecular pump. [Figure 3] FIG. 3 is an example of a time chart showing control when the current command value is larger than the detected value. [Figure 4] FIG. 4 is an example of a time chart showing control when the current command value is smaller than the detected value. [Figure 5] FIG. 5 is an example of a vertical cross-sectional view of another turbomolecular pump. [Figure 6] FIG. 6 is a partially enlarged view of FIG. [Figure 7] FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is an example of a plan view of the fixed disk. [Figure 9] FIG. 9 is an example of a bottom view of the fixed disk. [Figure 10] FIG. 10 is an example of a longitudinal cross-sectional view of a fixed disk. [Figure 11] FIG. 11 is a graph showing the relationship between the intake pressure and the back pressure of a Sigburn type exhaust mechanism. [Figure 12] FIG. 12 is a vertical cross-sectional view of a turbomolecular pump according to one embodiment. [Figure 13] FIG. 13 is a partially enlarged view of FIG. [Figure 14] FIG. 14 is an example of a bottom view of the inflow guide portion according to one embodiment. [Figure 15] FIG. 15 is a cross-sectional view taken along line XV-XV in FIG. [Figure 16] FIG. 16 is a schematic diagram illustrating the shape of the peaks of the inflow guide portion. [Figure 17] FIG. 17 is a graph showing the simulation results of the relationship between the inner radius of the inlet guide portion and the Sigburn stage inlet pressure. [Figure 18]FIG. 18 is an example of a partial cross-sectional view of an inflow guide portion according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vacuum pump according to one embodiment will be described below with reference to the drawings. Some of the drawings show X-, Y-, and Z-axes, and each axis is drawn so that it is in a common direction in each drawing. However, these directions are merely for the convenience of explanation and do not limit the installation mode of the vacuum pump in any way. Furthermore, the same components may be assigned a reference number in one drawing and omitted in other drawings.

[0010] <Basic configuration of turbomolecular pump> FIG. 1 shows the basic configuration of a turbomolecular pump 100, which is an example of a vacuum pump. The upper part of FIG. 1 is the upstream (intake) side of this turbomolecular pump 100, and an intake port 101 is connected to a vacuum chamber (not shown) of a target device such as a semiconductor manufacturing device. The lower part of FIG. 1 is the downstream (exhaust) side of the turbomolecular pump 100, and an exhaust port 133 is connected to, for example, an auxiliary pump (not shown). This turbomolecular pump 100 can be used in a vertical position as shown in FIG. 1, as well as in an inverted vertical position, a horizontal position, or an inclined position.

[0011] 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 cylinder 127. Inside the outer cylinder 127 is provided a rotor 103 having a plurality of rotors 102 (102a, 102b, 102c, etc.), which are turbine blades for sucking in and exhausting gas, formed radially and in multiple stages around its periphery. A rotor shaft 113 is attached to the center of this rotor 103, and this rotor shaft 113 is levitated and 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 metal such as aluminum or an aluminum alloy.

[0012] The upper radial electromagnets 104 are arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to each upper radial electromagnet 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 changes in the inductance of the conductive windings, which change 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 the detected displacement to the control device 200.

[0013] 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 a position signal detected by the upper radial sensor 107, and an amplifier circuit 150 (described later) shown in Figure 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.

[0014] The rotor shaft 113 is made of a high magnetic permeability material (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnets 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. The lower radial electromagnets 105 and the lower radial sensors 108 are arranged in the same manner as the upper radial electromagnets 104 and the upper radial sensors 107, and adjust the radial position of the lower side of the rotor shaft 113 in the same manner as the radial position of the upper side.

[0015] 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 highly magnetic permeable material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and an axial position signal is sent to control device 200.

[0016] 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 disc 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disc 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0017] In this way, the control device 200 appropriately adjusts the magnetic forces 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.

[0018] Meanwhile, motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround rotor shaft 113. Each magnetic pole is controlled by control device 200 so as to rotate rotor shaft 113 via electromagnetic force acting between the magnetic pole and rotor shaft 113. Motor 121 also incorporates a rotational speed sensor (not shown), such as a Hall element, resolver, or encoder, and the rotational speed of rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

[0019] Furthermore, 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 rotational speed sensor to detect the position of the magnetic pole.

[0020] A plurality of fixed blades 123 (123a, 123b, 123c...) are arranged at small gaps from the rotating blades 102 (102a, 102b, 102c...). Each of the rotating blades 102 (102a, 102b, 102c...) is formed at an angle of a predetermined degree from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward through collision. The fixed blades 123 (123a, 123b, 123c...) are made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing any of these metals as an ingredient.

[0021] Similarly, the fixed blades 123 are 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 rows of rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral ends of the fixed blades 123 are supported by being inserted between a plurality of stacked rows of fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0022] The fixed vane spacer 125 is a ring-shaped member made of a metal such as aluminum, iron, stainless steel, or copper, or an alloy containing any of these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed vane 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 communicates with 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.

[0023] Furthermore, depending on the application of the turbomolecular pump 100, a threaded spacer 131 is disposed between the lower portion of the stator spacer 125 and the base portion 129. The threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing any of these metals, and has multiple spiral thread grooves 131a engraved on its inner circumferential surface. The spiral direction of the threaded grooves 131a corresponds to the direction in which exhaust gas molecules are transported toward the exhaust port 133 when they move in the rotational direction of the rotor 103. A cylindrical portion 102d hangs down from the lowest portion of the rotor 103, adjacent to the rotor blades 102 (102a, 102b, 102c, etc.). The outer circumferential surface of this cylindrical portion 102d is cylindrical and protrudes toward the inner circumferential surface of the threaded spacer 131, and is adjacent to the inner circumferential 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 sent to the base portion 129 while being guided by the thread groove 131a.

[0024] The base portion 129 is a disk-shaped member that forms the base of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, stainless steel, etc. 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.

[0025] In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the action of the rotor 102 and the stator 123 draws exhaust gas from the chamber through the intake port 101. The rotational speed of the rotor 102 is typically 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 through the intake port 101 passes between the rotor 102 and the stator 123 and is transported 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 conduction of heat generated by the motor 121, but this heat is transferred to the stator 123 side by radiation or conduction through gas molecules of the exhaust gas.

[0026] The stator spacers 125 are joined together at their outer peripheries and transmit to the outside heat received by the stator 123 from the rotor 102 and frictional heat generated when exhaust gas comes into contact with the stator 123.

[0027] 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 formed on the inner circumferential surface of the threaded spacer 131. However, there are also cases where the thread groove is formed on the outer circumferential surface of the cylindrical portion 102d, and a spacer having a cylindrical inner circumferential surface is disposed around the outer circumferential surface of the cylindrical portion 102d.

[0028] Depending on the application of the turbomolecular pump 100, the electrical equipment section may be surrounded 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, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., and the interior of this stator column 122 may be kept at a predetermined pressure by purge gas.

[0029] 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 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.

[0030] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that have been individually adjusted and identified for the model. To store these control parameters, the turbomolecular pump 100 is provided with an electronic circuit section 141 within its body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEPROM, 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 a base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom lid 145.

[0031] In the semiconductor manufacturing process, some process gases introduced into a chamber have the property of solidifying 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 inlet port 101 and highest at the outlet port 133. If the pressure of the process gas exceeds a predetermined value or the temperature falls below a predetermined value while the process gas is being transferred from the inlet port 101 to the outlet port 133, the process gas solidifies and adheres to and accumulates inside the turbomolecular pump 100.

[0032] For example, when SiCl4 is used as the process gas in an Al etching system, the low vacuum (760 [torr] to 10 -2The vapor pressure curve shows that at low pressures (approximately 20°C) and pressures of 100[torr], solid products (e.g., AlCl3) precipitate and adhere to and accumulate inside the turbomolecular pump 100. When process gas deposits accumulate inside the turbomolecular pump 100, these deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The aforementioned products tend to solidify and adhere to high-pressure areas near the exhaust port 133 and the threaded spacer 131.

[0033] Therefore, in order to solve this problem, conventionally, a heater (not shown) or a circular water-cooled pipe 149 is wrapped around the outer periphery of the base portion 129, etc., and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 129, and the heating of the heater and the cooling by the water-cooled pipe 149 are controlled based on the signal from this temperature sensor to maintain the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; Temperature Management System).

[0034] Next, a description will be given of the amplifier circuit 150 that controls excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B in the turbomolecular pump 100. A circuit diagram of this amplifier circuit 150 is shown in FIG.

[0035] 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to a positive electrode 171a of a power supply 171 via a transistor 161, and the other end is connected to a negative electrode 171b of the power supply 171 via a current detection circuit 181 and a transistor 162. 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.

[0036] At this time, the transistor 161 has a diode cathode terminal 161a connected to the positive electrode 171a and an anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has a diode cathode terminal 162a connected to the current detection circuit 181 and an anode terminal 162b connected to the negative electrode 171b.

[0037] Meanwhile, current regeneration diode 165 has its cathode terminal 165a connected to one end of electromagnet winding 151 and its anode terminal 165b connected to negative electrode 171b. Similarly, current regeneration diode 166 has its cathode terminal 166a connected to positive electrode 171a and its anode terminal 166b connected to the other end of electromagnet winding 151 via current detection circuit 181. Current detection circuit 181 is configured, for example, with a Hall sensor type current sensor or an electrical resistance element.

[0038] The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled in 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.

[0039] 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 in the figure of the control device 200, and this amplifier control circuit 191 is configured to switch the transistors 161 and 162 on / off.

[0040] 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. Based on the comparison result, the amplifier control circuit 191 determines the size of the pulse width (pulse width times Tp1 and Tp2) to be generated within a control cycle Ts, which is one period under PWM control. As a result, gate drive signals 191a and 191b having these pulse widths are output from the amplifier control circuit 191 to the gate terminals of the transistors 161 and 162.

[0041] It is necessary to control the position of rotor 103 at high speed and with strong force when, for example, rotor 103 passes through a resonance point during acceleration of its rotational speed or when a disturbance occurs during constant-speed operation. For this reason, a voltage of, for example, about 50 V is used as power supply 171 so that the current flowing through electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between positive electrode 171a and negative electrode 171b of power supply 171 to stabilize power supply 171.

[0042] In this configuration, when both transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereinafter referred to as electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

[0043] Furthermore, when one of the transistors 161 and 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, 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 and 162 in this manner, high-frequency noise such as harmonics generated in the turbomolecular 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.

[0044] 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 corresponding to pulse width time Tp1 only once in a control cycle Ts (for example, 100 μs), as shown in Fig. 3. Therefore, during this period, the electromagnet current iL increases toward a current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.

[0045] 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 corresponding to pulse width time Tp2 only once during the control cycle Ts, as shown in Fig. 4. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from the negative pole 171b to the positive pole 171a via diodes 165 and 166.

[0046] In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, a flywheel current is maintained in the amplifier circuit 150 during this period.

[0047] In the turbomolecular pump 100 described above, for example, the outer cylinder 127 and the base portion 129 are mainly combined to form a single housing (hereinafter referred to as "casing"). The exhaust mechanism provided in the casing can be divided into a turbomolecular pump mechanism portion formed by the rotor 102, the fixed blades 123, etc., and a groove exhaust mechanism portion formed by the cylindrical portion 102d and the threaded spacer 131, etc. The groove exhaust mechanism portion is not limited to one formed by the cylindrical portion 102d and the threaded spacer 131, etc., and may be formed by, for example, a Sigburn-type exhaust mechanism portion 301 (described later) or a Holweck-type exhaust mechanism portion. The exhaust mechanism of the turbomolecular pump 100 may be formed by any one of the groove exhaust mechanism portions, or a combination of two or more of them.

[0048] <Sigburn type exhaust mechanism> Next, other aspects of the above-mentioned groove exhaust mechanism will be described with reference to Fig. 5 to Fig. 11. Fig. 5 is a longitudinal cross-sectional view of the turbomolecular pump 100A, and Fig. 6 is a partially enlarged view showing the right side of the rotation axis of the rotor shaft 113 in Fig. 5. The turbomolecular pump 100A is equipped with the above-mentioned turbomolecular pump mechanism 201 and a Sigburn type exhaust mechanism 301 as its groove exhaust mechanism. The Sigburn type exhaust mechanism 301 is provided next to (immediately downstream of) the turbomolecular pump mechanism 201 so as to be spatially continuous with it.

[0049] 5 differs from FIG. 1 in that the groove exhaust mechanism is a Sigburn-type exhaust mechanism 301, but the other basic configurations are the same. Therefore, repeated explanations of the configurations and effects of the common parts will be omitted. Depending on the application, the turbomolecular pump 100A may be provided with another groove exhaust mechanism, such as a Holweck-type exhaust mechanism (not shown), in the next stage (immediately downstream side) of the Sigburn-type exhaust mechanism 301.

[0050] The Sigburn-type exhaust mechanism unit 301 is a Sigburn-type exhaust mechanism, and is generally composed of a rotating disk 320 (320a, 320b) and a fixed disk 330 (330a). The rotating disk 320 (320a, 320b) and the fixed disk 330 (330a) are made of a metal such as aluminum, iron, stainless steel, or copper, or an alloy containing any of these metals as an ingredient.

[0051] Rotating disks 320 (320a, 320b) are generally annular plates that are integrally formed on the outer periphery of cylindrical rotor 103. Rotating disks 320a, 320b are provided coaxially with rotor 103 and spaced apart in the axial direction. Rotating disks 320 (320a, 320b) rotate in the same direction (rotational direction) together with rotor 103, rotor blades 102, etc., when driven by motor 121. In FIG. 6 and other figures, Sigburn-type exhaust mechanism 301 includes two (two stages) rotating disks 320a, 320b, but the number of rotating disks may be one (single stage) or three (three stages) or more, depending on the combination with a fixed disk. In the following, of one (single stage) or multiple (multiple stages) rotating disks 320, the rotating disk 320 arranged closest to the intake port 101 may be referred to as a first rotating disk 320a.

[0052] The fixed disk 330 (330a) is a generally annular plate and is integrally assembled to the casing. The fixed disk 330 (330a) may be formed of a single annular plate, or may be formed of a plurality of arc-shaped segments. The fixed disk 330a is disposed between the two rotating disks 320a and 320b with a predetermined clearance therebetween. In FIG. 5 and other figures, the Sigburn-type exhaust mechanism 301 includes one (first stage) fixed disk 330a, but may include two or more (first stage) fixed disks depending on the combination with the rotating disks. Hereinafter, of the one (first stage) or multiple (multiple stages) fixed disks 330, the fixed disk disposed closest to the intake port 101 may be referred to as the first fixed disk 330a.

[0053] 5, the number of stages of fixed disks 330 is one, and the number of stages of rotating disks 320 is two. These rotating disks 320 and fixed disks 330 are alternately arranged in the order of rotating disk 320 (first rotating disk 320a), fixed disk 330 (first fixed disk 330a), and rotating disk 320 (second rotating disk 320b) from the intake port 101 side.

[0054] In the Sigburn type exhaust mechanism 301, spiral grooves are provided on the opposing surfaces of at least one of the opposing rotating disk 320 and fixed disk 330. In this embodiment, the rotating disk 320 is a substantially flat plate, and spiral grooves 334 are provided on both surfaces of the fixed disk 330, i.e., on both the upstream side (the side of the intake port 101) and the downstream side (the side of the intake port 101).

[0055] FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. 5 , and schematically illustrates the fixed disk 330 of the Sigburn-type exhaust mechanism 301 as viewed from the intake port 101 side. FIGS. 8 to 10 are plan views, bottom views, and partial cross-sectional views of the fixed disk 330. The fixed disk 330 includes, for example, a substantially annular disk portion 331 and a ridge portion 332 protruding from the disk portion 331 toward the rotating disk 320. The rotor 103, the rotor shaft 113, and the like are inserted through a through-hole in the center of the disk portion 331. Although not necessarily limited thereto, the fixed disk 330 of this embodiment includes a substantially annular fixed spacer 335 (see FIG. 10 , etc.) integrally formed on the outer periphery of one surface of the disk portion 331 (here, the surface on the intake port 101 side). The fixed spacer 335 is an element that performs the same function as the fixed wing spacer 125 described above.

[0056] A plurality of ridges 332 are provided on both surfaces of the fixed disk 330, each extending in a spiral (whorl) shape. In FIG. 7, the ridges 332 provided on the upstream surface of the fixed disk 330 are indicated by solid lines, and the ridges 332 provided on the downstream surface are indicated by dotted lines. When the rotating disk rotates in the rotation direction indicated by arrow R, the ridges 332 provided on the upstream surface extend in the same direction (forward direction) as the rotation direction, which is perpendicular to the axial direction, from the outside (outer periphery) to the inside (inner periphery). Furthermore, the ridges 332 provided on the downstream surface extend in the opposite direction to the ridges 332 provided on the upstream surface in a plan view as the rotation direction moves from the inside to the outside. However, as shown in Figure 9, the ridge portion 332 provided on the downstream surface extends in the same direction (forward direction) as the rotation direction (arrow R) as it moves from the inside (inner peripheral side) to the outside (outer peripheral side) in the radial direction when viewed from the bottom.

[0057] The surface of the disk portion 331 that is not provided with the peaks 332 forms valleys 333 that are recessed relative to the peaks 332. The peaks 332 and valleys 333 form spiral grooves 334. A gas flow path for transporting gas is formed by the spiral grooves 334 of the fixed disk 330 and the opposing rotating disk 320. Note that the width, depth, etc. of the spiral grooves 334 may be adjusted so that the flow path step area gradually decreases toward the downstream side, for example.

[0058] In this Sigburn type exhaust mechanism 301, when the rotating disk 320 rotates at high speed, gas molecules present inside the spiral grooves collide with the rotating disk 320, imparting momentum to the gas molecules along the rotational direction. The gas molecules collide with the flow path wall of the gas flow path and are transported toward the exhaust port 133 by the component of this momentum along the longitudinal direction of the spiral grooves 334. This is called the molecular drag effect. Note that, in the turbomolecular pump mechanism 201, the gas molecules are transported along the axial direction, as shown by the dotted line in FIG. 6, for example. In contrast, in the Sigburn type exhaust mechanism 301 downstream of the turbomolecular pump mechanism 201, the gas molecules are transported in the radial direction.

[0059] Specifically, in the Sigburn type exhaust mechanism 301, gas molecules move from the outside to the inside in the radial direction through a spiral gas flow path constructed on the upstream side of the fixed disk 330, and then move from the inside to the outside in the radial direction through a gas flow path constructed on the downstream side of the fixed disk 330, and are sent to the exhaust port 133. Referring to Fig. 7 , on the upstream side of the fixed disk 330, the gas molecules move from the outside to the inside in the radial direction through the spiral gas flow path as shown by the solid arrow, and on the downstream side of the fixed disk 330, the gas molecules are transferred from the inside to the outside in the radial direction through the gas flow path as shown by the dotted arrow.

[0060] Indicators commonly used to express the exhaust performance of a vacuum pump include "exhaust speed," "compression performance," and "back pressure performance." These indicators are defined, for example, in Japanese Industrial Standard JIS B 8329-1:2015, and the values ​​of each indicator can be determined in accordance with the standard. Among these indicators, "exhaust speed" is an indicator expressed as the volume of gas passing through the intake port per unit time. "Compression performance" is an indicator of how much gas can be compressed and is expressed as the ratio of the intake port pressure to the exhaust port pressure when the flow rate is zero. As mentioned above, "back pressure performance" is an indicator of the degree to which changes in back pressure affect the intake pressure.

[0061] 11 is a graph showing the relationship between intake pressure and back pressure, illustrating the exhaust performance of a Sigburn exhaust system. The horizontal axis represents back pressure (the pressure at the exhaust port of the Sigburn exhaust system), and the vertical axis represents intake pressure (the pressure at the intake port of the Sigburn exhaust system), both of which are expressed on a logarithmic scale. The unit of exhaust port pressure is [Torr], and the unit of intake port pressure (Ps) in this case is typically [mTorr].

[0062] Because the pumping speed of a vacuum pump varies depending on the degree of vacuum, it is common to connect an auxiliary pump to the exhaust (downstream) side to operate the pump within the appropriate vacuum range. Here, for a vacuum pump at the desired vacuum level, the pressure (back pressure) on the auxiliary vacuum side generated by the auxiliary pump is gradually increased at a constant flow rate. As shown in Figure 11(a), the vacuum level (suction pressure) on the intake side remains almost constant up to a certain pressure, but deteriorates rapidly once the pressure exceeds that limit. The wider the back pressure range over which the suction pressure remains constant (see "Good" in the figure), the less the back pressure affects the suction pressure, and the better the back pressure dependency. Furthermore, the faster the pumping speed, the lower the curve showing the relationship between suction pressure and back pressure, as shown in Figure 11(b) (see "Good" in the figure).

[0063] It is known that the Sigburn exhaust mechanism has better back pressure performance than other exhaust mechanisms. To further improve this back pressure performance, it is effective to increase the gas flow path length, that is, to increase the number of stages in the Sigburn exhaust mechanism 301. Increasing the gas flow path length is also effective in improving compression performance. However, as shown in FIG. 11(c), increasing the number of stages in the Sigburn exhaust mechanism 301 shifts the curve showing the relationship between suction pressure and back pressure to the upper right (see "multiple stages" in the figure). In other words, there is a tradeoff between improving back pressure performance and decreasing exhaust speed.

[0064] <Inlet guide section> Next, a turbomolecular pump 300 according to the present technology will be described with reference to Figs. 12 to 18. Fig. 12 is a longitudinal cross-sectional view of the turbomolecular pump 300 according to one embodiment, and Fig. 13 is a partially enlarged view thereof. The turbomolecular pump 300 is provided with an inflow guide section 310 downstream of the turbomolecular pump mechanism section 201 and immediately upstream of the Sigburn type exhaust mechanism section 301. Fig. 12 is the same as Fig. 5 except for the inflow guide section 310, and redundant description of the configuration and effects of the common sections will be omitted.

[0065] Inflow guide 310 is an element that guides the flow of gas flowing into Sigburn exhaust mechanism 301. Inflow guide 310 is provided upstream of first rotating disk 320a of Sigburn exhaust mechanism 301 with a predetermined clearance between them. Inflow guide 310 is a generally annular plate, and is a static element that is integrally assembled to the casing. Inflow guide 310 is made of metal such as aluminum, iron, stainless steel, or copper, or an alloy containing any of these metals as a component.

[0066] Fig. 14 is an example of a bottom view (viewed from the exhaust port 133 side) of the inflow guide portion 310, and Fig. 15 is a cross-sectional view taken along line XV-XV thereof. Fig. 16 is a schematic diagram illustrating the shape of the peaks of the inflow guide portion. The inflow guide portion 310 includes a guide disk 311 and a ridge portion 312. Although not necessarily limited to this, the inflow guide portion 310 of this embodiment is integrally provided with a substantially annular fixed spacer 315 on the outer circumferential edge portion of an opposing surface 311a (the surface on the exhaust port 133 side) that faces the first rotating disk 320a. The fixed spacer 315 is an element that performs the same function as the fixed vane spacer 125 described above.

[0067] The guide disk 311 is a plate having a substantially circular ring shape. As will be described in detail later, the inner diameter of the guide disk 311 is typically configured to be larger than the inner diameter of the first fixed disk 330a. Furthermore, for example, the guide disk 311 and the first rotating disk 320a are configured so that a molecular drag effect is exerted when the first rotating disk 320a rotates. The plate surface of the guide disk 311 may be flat, or may be sloped so that the thickness gradually increases from the center to the outer periphery, as shown in FIG. 15 . The rotating body 103, the rotor shaft 113, etc. are inserted into a through hole in the center of the guide disk 311.

[0068] The ridges 312 are integrally formed with the guide disc 311 so as to protrude from the guide disc 311 toward the first rotating disc 320a. The ridges 312 are formed on the opposing surface 311a of the guide disc 311 that faces the first rotating disc 320a, and are not formed on the opposite surface (i.e., the upstream side). The ridges 312 of this embodiment have a strip-like shape with a substantially rectangular cross section. The guide disc 311 of this embodiment is provided with a plurality of ridges 312, but the number of ridges 312 is not particularly limited and may be one or more.

[0069] The peaks 312 are generally spiral-shaped (whorl-shaped), as shown in Fig. 14, for example. When the first rotating disk 320a rotates in the direction indicated by the arrow R, the peaks 312 extend radially from the inside to the outside in the same direction as the rotation direction (forward direction). More specifically, as shown in Figs. 16(a) to 16(c), for example, the peaks 312 are configured so that, with respect to the radial direction perpendicular to the rotation axis of the rotating body 103, the outer circumferential side is inclined in the forward direction of the rotation direction (arrow R) and the inner circumferential side is inclined in the opposite direction to the rotation direction.

[0070] Each peak 312 may be formed in a straight line, as shown in FIG. 16(a), for example. Each peak 312 may be formed in a broken line shape, bending at one or more points, as shown in FIG. 16(b). Each peak 312 may be formed in a smoothly curved line shape, as shown in FIG. 16(c). Each peak 312 may have any combination of these shapes, as long as it slopes in the same direction as the rotational direction from the inner to the outer radial direction. When multiple peaks 312 are provided on one guide disc 311, the peaks 312 may have the same shape, or some or all of them may have different shapes.

[0071] Portions of opposing surface 311a of guide disk 311 where ridges 312 are not provided become valleys 313 that are recessed relatively to ridges 312 (see FIG. 15). Peaks 312 and valleys 313 form spiral grooves 314. The space surrounded by spiral grooves 314 of guide disk 311 and first rotating disk 320a facing it can serve as an introduction gas flow path for introducing gas mainly into Sigburn-type exhaust mechanism 301.

[0072] By providing such an inflow guide portion 310 in the upstream stage (immediately upstream side) of the Sigburn type exhaust mechanism portion 301, gas flowing from the outside of the first rotating disk 320a into the Sigburn type exhaust mechanism portion 301 is transferred from the inside to the outside in the radial direction due to the drag effect. At this time, the gas molecules that have flowed into the inflow guide portion 310 are prevented by the ridge portions 312 from returning from the inside to the outside in the radial direction. This makes it possible to improve the back pressure dependency while preventing a decrease in the pumping speed in the Sigburn type exhaust mechanism portion 301. Below, the mechanism by which the inflow guide portion 310 prevents a decrease in the pumping speed in the Sigburn type exhaust mechanism portion 301 according to the present technology will be described, along with verification by thermal fluid analysis.

[0073] <Fluid analysis> In a vacuum pump, we performed a thermal fluid analysis to evaluate how the exhaust characteristics change when the inlet guide section 310 is combined with and not combined upstream of the Sigbahn type exhaust mechanism section 301. In addition, when the inlet guide section 310 is combined, we also evaluated the exhaust characteristics when the dimensions of the inlet guide section 310 (guide disk) are changed. For the analysis, we used commercially available thermal fluid analysis software.

[0074] An analytical model of the flow path of the Sigburn type exhaust mechanism for the simulation was created by extracting the gas flow path from the position where the gas passed through the turbomolecular pump mechanism 201 to the position where the gas passed through the Sigburn type exhaust mechanism 301, based on the CAD model of the turbomolecular pump 300 shown in Figures 6 and 12, etc. Note that in order to evaluate the exhaust characteristics of the Sigburn type exhaust mechanism 301 in more detail, the Sigburn type exhaust mechanism 301 in the analytical model was a multi-stage Sigburn type having four rotating disks 320 and three fixed disks 330.

[0075] The pressure before the Sigburn exhaust mechanism (i.e., suction pressure) was calculated when the pressure after passing through the Sigburn exhaust mechanism (i.e., back pressure) was set to a predetermined pressure. The Reynolds-averaged Navier-Stokes (RANS) model was used for turbulence analysis, and the k-ε model was applied to evaluate the Reynolds stress, to simulate the pressure distribution of the compressed fluid N2 in the flow path.

[0076] The suction pressure was calculated for a case where the inflow guide portion 310 was not provided (reference) and for a case where the inflow guide portion 310 was provided and its inner diameter was changed in three ways (Nos. 1 to 3). Below, with reference to Fig. 13, a method for expressing the change in the inner diameter of the inflow guide portion 310 will be described.

[0077] <Rotating disc reference> When the inner diameter of inflow guide portion 310 is changed, its shape can be expressed from various viewpoints. One indicator is the position of inner peripheral end portion 316 (see FIG. 13, etc.) of inflow guide portion 310 in the radial direction relative to the opposing first rotating disk 320a. This is because it is believed that inflow guide portion 310 can appropriately guide gas toward Sigburn-type exhaust mechanism portion 301 due to the molecular drag effect generated between inflow guide portion 310 and first rotating disk 320a, and the momentum imparted to gas molecules is thought to be related to the overlap ratio between inflow guide portion 310 and first rotating disk 320a.

[0078] In this fluid analysis, the shapes of the multiple rotating disks 320 (320a...) in the analysis model are essentially the same, so the following explanation will be based on the rotating disk 320. If multiple rotating disks 320 (320a...) are provided and have different shapes, the "rotating disk 320" in the following explanation can be read as the "first rotating disk 320a."

[0079] In this case, as shown in FIG. 13, for example, the position (root portion) where the rotating disk 320 connects to the rotor 103 is defined as the base end 321 of the rotating disk 320, and the position is expressed as the percentage of the rotating disk 320 from the base end 321 at which the inner peripheral end 316 of the inflow guide portion 310 is located. Also, the outer peripheral end of the rotating disk 320 is defined as the outer peripheral end 322. The base end 321 of the rotating disk 320 is located at the distance from the center of the rotating disk 320 to the radius of the rotor 103 (hereinafter referred to as the "inner peripheral radius R of the rotating disk 320" for convenience). RI Therefore, the radial dimension L of the rotary disk 320 is R1 (Width of the ring) is calculated by the following formula: L R1 =R RO -R RI where R RO is the radius of the outer periphery of the rotating disk 320, and is the dimension from the center of the rotating disk 320 to the outer periphery edge 322.

[0080] Next, the inner peripheral end 316 of the inflow guide portion 310 is formed by dividing the inflow guide portion 310 by the inner peripheral radius RGI Therefore, the dimension L from the base end 321 of the rotary disk 320 to the inner peripheral end 316 of the inflow guide portion 310 is G1 is the radius R of the inner periphery of the inflow guide portion 310 GI From the above, the inner radius R of the rotating disk 320 RI The dimension is calculated by subtracting the following formula: L G1 =R GI -R RI ; is expressed as

[0081] From the above, the position of the inner peripheral end 316 of the inflow guide portion 310 relative to the rotary disk 320 from the base end 321 can be expressed by the following equation. Position of the inner peripheral end 316 of the inflow guide portion 310 = (dimension L from the base end 321 to the inner peripheral end 316 G1 ) ÷ (Radial dimension L of the rotating disk 320 R1 ) x 100 =(R GI -R RI ) / (R RO -R RI ) x 100

[0082] Based on this rotating disk standard, the positions of the inner peripheral end 316 of the inflow guide portion 310 of the three analytical models are as follows: Simulation No. 1: 26%, Simulation No. 2: 57%, and Simulation No. 3: 80%. Note that the larger the numerical value of this index, the larger the inner diameter (or inner peripheral radius) of the inflow guide portion 310 and the smaller the overlap ratio with the rotating disk 320.

[0083] <Flow path area standard> On the other hand, as another index for expressing the shape of the inflow guide portion 310, it is also possible to use the area where the flow path widens as a reference, rather than the first rotating disk 320a as a reference. For example, as shown in FIG. 13, there is a dimension L for the return flow path between the outer peripheral end 322 of the rotating disk 320 and the fixed spacers 315, 335. R2 The exhaust characteristics of the Sigburn type exhaust mechanism 301 are ensured by the dimension L of such a turn-back flow path.R2 (L G3 ,L S2 ) is a reasonable consideration.

[0084] Therefore, the radial dimension L of the rotating disk 320 in the above-mentioned rotating disk standard R1 (Width of the annulus)" and "Dimension L in the radial direction of the flow path area" G2 " can be used. Here, the flow path region refers to a region of the Sigburn-type exhaust mechanism 301 that can serve as a gas flow path, and in the radial direction, it is the region from the base end 321 of the rotating disk 320 to the base ends 317, 337 of the inflow guide 310 or the fixed disk 330. The base end 317 of the inflow guide 310 is the position where the guide disk 311 connects to the fixed spacer 315 (the position where the guide disk 311 protrudes from the inner circumferential surface of the fixed spacer 315). The base end 337 of the fixed disk 330 is the position where the disk portion 331 connects to the fixed spacer 335 (the position where the disk portion 331 protrudes from the inner circumferential surface of the fixed spacer 335).

[0085] The radial dimension of the flow area is given by the following formula: L G2 =R GO -R RI where R GO is the outer radius of the guide disc 311 of the inflow guide portion 310, and is the dimension from the center of the inflow guide portion 310 to the base end portion 317 (i.e., not including the fixed spacer 315 portion). The dimension of the flow path region in the radial direction is, for example, expressed by the following formula: L G2 =R SO -R RI ; where R SO is the outer radius of the disk portion 331 of the fixed disk 330, and is the dimension from the center of the fixed disk 330 to the base end portion 337 (that is, not including the fixed spacer 335 portion). The radial position of the inner peripheral end 316 of the inflow guide portion 310 relative to the flow path region can be expressed by the following equation: Position of the inner peripheral end 316 of the inflow guide portion 310 = (dimension L from the base end 321 to the inner peripheral end 316) G1 ) ÷ (Radial dimension of flow path area LG2 ) x 100 =(R GI -R RI ) / (R GO -R RI ) x 100

[0086] Based on these flow path area criteria, the positions of the inner peripheral end 316 of the inflow guide portion 310 in the three simulated cases are as follows: Simulation No. 1: 25%, Simulation No. 2: 55%, and Simulation No. 3: 78%. This index indicates that the larger the numerical value, the larger the inner diameter (or inner peripheral radius) of the inflow guide portion 310 and the smaller the overlap ratio with the rotating disk 320.

[0087] <Simulation results> Simulation results of the pressure distribution of compressed fluid N2 in the flow path showed that by combining inflow guide 310 in front of Sigburn exhaust mechanism 301 (Nos. 1 to 3), the pressure in the space in front of Sigburn exhaust mechanism 301 was reduced overall compared to when inflow guide 310 was not combined (reference). Furthermore, it was found that when inflow guide 310 was not combined (reference), the pressure in the front of Sigburn exhaust mechanism 301 was roughly uniform, whereas when inflow guide 310 was provided (Nos. 1 to 3), large pressure changes occurred in the front of Sigburn exhaust mechanism 301. It was found that the pressure changes occurred particularly within inflow guide 310.

[0088] This is believed to be due to the following reason. For example, as shown in FIGS. 13 and 14 , when the rotating disk 320 rotates in a predetermined rotation direction (arrow R) during operation of the turbomolecular pump 300, a gas fluid is guided into the inlet gas flow passage between the ridges 312 of the inlet guide 310 in the upstream stage of the Sigburn-type exhaust mechanism 301 provided with the inlet guide 310. The gas fluid moves in a spiral pattern along the inlet gas flow passage from the inside to the outside in the radial direction. The gas fluid collides with the inner circumferential surface of the fixed spacer 315 at the outer end of the inlet gas flow passage, and a portion of the gas fluid turns back along the inlet gas flow passage toward the downstream side and is sent to the Sigburn-type exhaust mechanism 301. The other portion of the gas fluid attempts to move radially inward within the inlet gas flow passage. However, the gas fluid attempting to return radially inward is prevented from further movement by the presence of the ridges 312 of the inlet guide 310.

[0089] The peaks 312 of the inflow guide portion 310 are inclined in the direction of rotation (arrow R) as they extend radially outward, thereby promoting the flow of the gas fluid radially outward and inhibiting the gas fluid from moving radially inward. As a result, it is believed that within the inflow guide portion 310, a region where the pressure of the gas fluid is relatively low is formed radially inward from the peaks 312, while a region where the pressure of the gas fluid is relatively high is formed radially outward from the peaks 312. This also contributes to a reduction in overall pressure in the upstream space continuous with the inner periphery of the inflow guide portion 310 compared to the case where the inflow guide portion 310 is not provided (reference).

[0090] This reduction in the pressure in the space upstream of the inlet guide 310 and the Sigburn exhaust mechanism 301 (i.e., the suction pressure of the Sigburn exhaust mechanism 301) means that the pumping speed of the Sigburn exhaust mechanism 301 increases, as shown in FIG. 11(b). For example, the density of gas molecules is reduced in the space upstream of the inlet guide 310 and the Sigburn exhaust mechanism 301, and the drag effect allows the gas molecules to be pumped at a higher speed. As a result, for example, in the graph of FIG. 11(c), even with a multi-stage Sigburn exhaust mechanism 301, the curve showing the relationship between suction pressure and back pressure can be maintained lower, thereby achieving both improved back pressure performance and improved pumping speed.

[0091] FIG. 17 shows the relationship between the shape of the inlet guide section (based on the rotating disk) and the suction pressure of the Sigburn-type exhaust mechanism 301 obtained from the simulation results. The suction pressure of the Sigburn-type exhaust mechanism 301 is shown as a normalized value (%), with the suction pressure without the inlet guide section (baseline) set to 100. While this depends on the Sigburn-type exhaust mechanism 301, in this simulation, the suction pressure (relative value) of the Sigburn-type exhaust mechanism 301 with the inlet guide section 310 was 78% for No. 1, 74% for No. 2, and 86% for No. 3. FIG. 17 also confirms that by combining (a) the inlet guide section 310 in front of the Sigburn-type exhaust mechanism 301, the pressure in the space in front of the Sigburn-type exhaust mechanism 301 is significantly reduced compared to (b) the inlet guide section 310 is not combined. It was also found that the degree of suction pressure reduction changed when the inner diameter of the inlet guide section 310 was changed.

[0092] Specifically, combining the Sigburn exhaust mechanism 301 with the inflow guide 310 provides a pressure reduction effect in the upstream stage. However, if the inner diameter of the inflow guide 310 is too small or too large, the degree of pressure reduction tends to be small. For example, if the inner diameter of the inflow guide 310 is too small, a large proportion of the inflow guide 310 overlaps with the rotating disk 320, making it difficult for the gas fluid in the space upstream of the Sigburn exhaust mechanism 301 to be drawn into the inflow guide 310. This is thought to limit the pressure reduction effect of the inflow guide 310. Therefore, it is preferable to set the inner diameter of the inflow guide 310 so that the radial position of the inner peripheral end 316 of the inflow guide 310 relative to the rotating disk 320 is approximately 10% or more from the base end 321 of the rotating disk 320. The position of the inner peripheral end 316 of the inflow guide portion 310 is more preferably about 20% or more from the base end 321 side of the rotary disk 320, and may be, for example, about 30% or more, 40% or more.

[0093] On the other hand, if the inner diameter of the inflow guide portion 310 is too large, for example, the proportion of the inflow guide portion 310 overlapping the rotating disk 320 will be small, making it difficult to effectively take in the gas fluid in the space upstream of the Sigburn exhaust mechanism 301 into the inflow guide portion 310 or to effectively prevent the taken-in gas fluid from returning from the radially outer side to the radially inner side. This is thought to limit the suction pressure reduction effect of the inflow guide portion 310. Therefore, it is preferable that the inner diameter of the inflow guide portion 310 be set so that the radial position of the inner end portion 316 of the inflow guide portion 310 relative to the rotating disk 320 is approximately 90% or less from the base end portion 321 of the rotating disk 320. The position of the inner end portion 316 of the inflow guide portion 310 is more preferably approximately 80% or less from the base end portion 321 of the rotating disk 320, and may be, for example, approximately 70% or less, or approximately 60% or less.

[0094] For example, the inner peripheral end 316 of the inflow guide portion 310 may be disposed within a range of 10% to 90% in the radial direction perpendicular to the axial direction from the rotor shaft-side base end 337, where the first rotating disk 320a is connected to the rotor shaft 113, to the outer peripheral end 322 of the first rotating disk 320a of the one or more fixed disks 330. It is more preferable that the inner peripheral end 316 of the inflow guide portion 310 be disposed within a range of 40% to 60% from the rotor shaft-side base end 337 to the outer peripheral end 322 of the first rotating disk 320a.

[0095] As described above, the position of the inner peripheral end 316 of the inflow guide portion 310 relative to the rotating disk 320 does not change significantly even if the reference index is changed to the flow path area. Therefore, it is preferable to set the inner diameter of the inflow guide portion 310 so that the radial position of the inner peripheral end 316 of the inflow guide portion 310 relative to the flow path area is approximately 10% or more from the base end 321 of the rotating disk 320. It is more preferable that the position of the inner peripheral end 316 of the inflow guide portion 310 is approximately 20% or more from the base end 321 of the rotating disk 320 relative to the flow path area, and may be, for example, approximately 30% or more, 40% or more. It is also preferable to set the inner diameter of the inflow guide portion 310 so that the radial position of the inner peripheral end 316 of the inflow guide portion 310 relative to the flow path area is approximately 90% or less from the base end 321 of the rotating disk 320. It is more preferable that the position of the inner peripheral end 316 of the inflow guide portion 310 is approximately 80% or less of the flow path area from the base end 321 side of the rotating disk 320, and it may be, for example, approximately 70% or less, 60% or less.

[0096] As shown in FIG. 13, a dimension L for a return flow path is provided between the fixed disk 330 of the Sigburn type exhaust mechanism 301 and the outer surface of the rotor 103. S3 is ensured, but this dimension L S3 is usually several mm, and the radial dimension L of the rotating disk 320 R1 and the radial dimension L of the flow passage area G2is sufficiently small (for example, not much larger than 10%) compared to the first rotating disk 320a. Therefore, it is preferable that the inflow guide section 310 is configured to include a guide disk having an inner diameter larger than the inner diameter of the first fixed disk 330a, which is disposed facing the downstream side of the first rotating disk 320a among the one or more fixed disks 330. With this configuration, it is possible to suitably improve both the back pressure dependency and the exhaust speed of the Sigburn type exhaust mechanism section 301.

[0097] In addition, the width L of the guide disc 311 of the inflow guide portion 310 G4 (Radial dimension) is the width L of the fixed disk 330 S1 It is preferable that the width L of the guide disc 311 of the inflow guide portion 310 is about 10% or more (the radial dimension). Furthermore, it is more preferable that the width L of the guide disc 311 of the inflow guide portion 310 is about 20% or more, and may be, for example, about 30% or more, 40% or more. G4 (Radial dimension) is the width L of the fixed disk 330 S1 It is preferable that the width is 90% or less of the radial dimension. It is more preferable that the width is approximately 80% or less, and it may be, for example, approximately 70% or less, 60% or less, etc.

[0098] Furthermore, the guide disk 311 of the inflow guide section 310 may be provided with spiral grooves 314 that shorten the gas flow path length compared to the fixed disk 330 (first fixed disk 330a). In the Sigburn type exhaust mechanism 301, it is desirable to provide the gas flow path as long as possible from the viewpoint of improving exhaust performance, but in the inflow guide section 310, an introduction gas flow path that is too long may actually make it difficult to take in the gas fluid. With this configuration, both the back pressure dependency and the exhaust speed can be improved in a balanced manner.

[0099] The inflow guide portion 310 and the first fixed disk 330a having such a configuration are not limited thereto, but can be realized by configuring the spiral grooves 314 on the opposing surface 311a of the inflow guide portion 310 and the spiral grooves 334 on the first fixed disk 330a with the same spiral pattern, as shown in Figures 8 and 14. This is because the inflow guide portion 310 has a larger inner diameter than the first fixed disk 330a, which naturally shortens the flow path. Having the spiral grooves 314, 334 of the inflow guide portion 310 and the first fixed disk 330a with the same pattern has the advantage of simplifying the design and manufacturing of the inflow guide portion 310. Note that the "gas flow path length" here refers to the flow path length per inlet gas flow path in the inflow guide portion 310 or the flow path length per gas flow path in the first fixed disk 330a.

[0100] Furthermore, it is preferable that the distance between the valley portion 313 of the inflow guide portion 310 and the first rotating disk 320a be greater than the distance between the valley portion 333 of the first fixed disk 330a and the first rotating disk 320a. For example, it is preferable that the valley portion 313 of the inflow guide portion 310 be deeper (axial dimension) than the valley portion 333 of the first fixed disk 330a. This configuration makes it easier for the pressure reduced in the inflow guide portion 310 to be extended to the space upstream of the inflow guide portion 310, thereby suitably reducing the pressure in the space upstream of the Sigburn type exhaust mechanism 301. This is also preferable in that it makes it easier to take in the gas fluid into the inflow guide portion 310 and allows the gas fluid to be sent more smoothly from the inflow guide portion 310 to the Sigburn type exhaust mechanism 301. The depth of valleys 313, 333 may vary depending on the position even within one inflow guide member 310 and one first rotating disk 320a. Therefore, the "distance" or "depth" between valleys 313 of inflow guide member 310 and first rotating disk 320a referred to here may be the average "distance" or "depth" in the longitudinal direction of the gas flow path in one inflow guide member 310 or one first rotating disk 320a.

[0101] Furthermore, the radially outer end of the inlet gas flow passage of the inlet guide 310 may be positioned corresponding to the radially outer end of the spiral groove 334 of the first fixed disk 330a. This configuration allows the inlet gas flow passage of the inlet guide 310 to be connected to the gas flow passage in the Sigburn-type exhaust mechanism 301 via a shorter return flow passage. This configuration allows the gas fluid to be sent to the Sigburn-type exhaust mechanism 301 more smoothly. While not limited to this, for example, as shown in FIGS. 8 and 14, the spiral groove 314 on the opposing surface 311a of the inlet guide 310 and the spiral groove 334 on the first fixed disk 330a may be configured with the same spiral pattern, thereby easily positioning the radially outer end of the inlet gas flow passage of the inlet guide 310 and the radially outer end of the spiral groove 334 on the first fixed disk 330a in opposing positions. Even if the spiral pattern is the same in plan view, the gas flow passage depth may be different.

[0102] In the above embodiment, the inflow guide section 310 is configured to exert a molecular drag effect between itself and the first rotating disk 320a. However, the inflow guide section 310 does not necessarily have to be configured to exert a molecular drag effect between itself and the first rotating disk 320a. For example, the inflow guide section 310 may be configured to prevent gas flowing from the radially inner side to the radially outer side from returning from the radially outer side to the radially inner side in a gas flow introduced into the inflow guide section 310 by the exhaust force of the downstream Sigburn exhaust mechanism section 301. The inflow guide section 310 configured in this manner can also reduce the pressure in the space upstream of the Sigburn exhaust mechanism section 301, contributing to an improvement in the exhaust speed.

[0103] In the above embodiment, the ridges 312 of the inflow guide 310 are provided, for example, in the region facing the first rotary disk 320a, and are not provided in the return flow path. Specifically, in FIG. 13 etc., a predetermined clearance L is provided between the ridges 312 and the outer peripheral end of the flow path region (i.e., the inner peripheral surface of the fixed spacer 315). G3 However, the ridges 312 of the inflow guide portion 310 may have a shape that is continuously connected to the ridges 332 of the first fixed disk 330a disposed downstream.

[0104] FIG. 18 is an example of a partial cross-sectional view of an inflow guide section 310A according to another embodiment. For example, the ridges 312A of the inflow guide section 310A extend radially to the inner circumferential surface of the fixed spacer 315 and axially along the inner circumferential surface of the fixed spacer 315 to its lower end. In this case, although not specifically shown, the ridges 332 of the first fixed disk 330a are disposed radially inside the downwardly extending portions of the ridges 312A of the inflow guide section 310. This prevents the molecular drag effect from being impaired in the return flow path. Furthermore, the introduction gas flow path of the inflow guide section 310 and the gas flow path of the Sigburn-type exhaust mechanism 301 can be more reliably connected, allowing the gas fluid to be more smoothly delivered to the Sigburn-type exhaust mechanism 301.

[0105] The inflow guide portion in the above embodiment can be distributed independently as a vacuum pump replacement part, etc. In this respect, the present technology provides an inflow guide component for use in a vacuum pump to guide the inflow of gas. Here, the vacuum pump is a so-called Sigburn-type vacuum pump that includes one or more rotating disks and one or more fixed disks arranged axially opposite each of the one or more rotating disks, with spiral grooves having valleys and peaks on the opposing surfaces. The vacuum pump exhausts introduced gas through the interaction between the one or more rotating disks and the one or more fixed disks. The inflow guide component according to the present technology includes a guide disk and peaks protruding from the guide disk toward a first rotating disk, among the one or more rotating disks, closer to the intake port than a first rotating disk on the intake port side of the vacuum pump. By locating this inflow guide portion upstream of the rotating disk closest to the intake port of a Sigburn-type vacuum pump, both the back pressure dependency and the exhaust speed of the vacuum pump can be favorably improved.

[0106] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to combine the configuration of one embodiment with the configuration of another embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration. The above-described embodiment discloses at least the configurations described in the claims. [Explanation of symbols]

[0107] 100, 100A, 300... turbomolecular pump, 101... intake port, 102... rotor, 102d... cylindrical portion (rotating cylinder), 103... rotor, 113... rotor shaft, 123... stator, 125... stator spacer, 127... outer cylinder (casing), 129... base portion (casing), 133... exhaust port, 201... turbomolecular pump mechanism, 301... Sigburn type exhaust mechanism, 310, 310A... inlet guide portion, 311... guide circle Plate, 311a... opposing surface, 312, 312A... crest portion, 313... valley portion, 314... spiral groove, 315... fixed spacer, 316... inner peripheral end portion, 317... base end portion, 320... rotating disk, 320a... first rotating disk, 321... base end portion, 322... outer peripheral end portion, 330... fixed disk, 330a... first fixed disk, 331... disk portion, 332... crest portion, 333... valley portion, 334... spiral groove, 335... fixed spacer, 337... base end portion

Claims

1. a casing having an intake port; a rotor shaft disposed within the casing; one or more rotating disks rotatable together with the rotor shaft; one or more fixed disks arranged axially opposite each of the one or more rotary disks, and each having a spiral groove with a valley portion and a peak portion on an opposing surface; Equipped with a gas flow path is formed by the spiral groove facing the one or more rotating disks; A vacuum pump that exhausts gas introduced from the inlet port by interaction between the one or more rotating disks and the one or more fixed disks, an inflow guide portion for guiding an inflow of the gas, the inflow guide portion being located closer to the intake port than a first rotary disk that is closest to the intake port among the one or more rotary disks; The first rotary disk is provided with a return flow path along an outer peripheral end thereof. Vacuum pump.

2. The inflow guide portion is a guide disk having an inner diameter larger than an inner diameter of a first fixed disk arranged opposite to the downstream side of the first rotating disk among the one or more fixed disks, 2. The vacuum pump of claim 1.

3. The guide disc is a spiral groove having a valley portion and a peak portion is provided on a surface facing the first rotating disk, and the spiral groove has a shorter gas flow path length than that of the first fixed disk; 3. The vacuum pump according to claim 2.

4. A casing having an air intake; a rotor shaft disposed within the casing; one or more rotating disks rotatable together with the rotor shaft; one or more fixed disks arranged axially opposite each of the one or more rotary disks, and each having a spiral groove with a valley portion and a peak portion on an opposing surface; Equipped with a gas flow path is formed by the spiral groove facing the one or more rotating disks; A vacuum pump that exhausts gas introduced from the inlet port by interaction between the one or more rotating disks and the one or more fixed disks, an inflow guide portion for guiding an inflow of the gas is provided on the inlet port side of a first rotating disk of the one or more rotating disks, the first rotating disk being on the inlet port side; The inflow guide portion is a guide disk having an inner diameter larger than an inner diameter of a first fixed disk arranged opposite to the downstream side of the first rotary disk among the one or more fixed disks, the inflow guide portion is provided with a spiral groove having a valley portion and a peak portion on a surface facing the first rotary disk, The ridge portion of the inflow guide portion has a shape that is continuously connected to the ridge portion of the first fixed disk arranged downstream. Vacuum pump.

5. A casing having an air intake; a rotor shaft disposed within the casing; one or more rotating disks rotatable together with the rotor shaft; one or more fixed disks arranged axially opposite each of the one or more rotary disks, and each having a spiral groove with a valley portion and a peak portion on an opposing surface; Equipped with a gas flow path is formed by the spiral groove facing the one or more rotating disks; A vacuum pump that exhausts gas introduced from the inlet port by interaction between the one or more rotating disks and the one or more fixed disks, an inflow guide portion for guiding an inflow of the gas is provided on the inlet port side of a first rotating disk of the one or more rotating disks, the first rotating disk being on the inlet port side; the inflow guide portion includes a guide disk and a ridge portion protruding from the guide disk toward the first rotary disk, the ridges of the inflow guide portion and the guide disks form an introduction gas flow path that guides the gas from the inside to the outside in a radial direction perpendicular to the axial direction when the one or more rotary disks rotate, a radially outer end of the introduction gas flow path is disposed at a position corresponding to a radially outer end of the spiral groove of a first fixed disk, which is disposed opposite the downstream side of the first rotating disk among the one or more fixed disks; A vacuum pump characterized by:

6. In a radial direction perpendicular to the axial direction, The inner end of the inflow guide portion is disposed in a range of 10% to 90% from a rotor shaft side base end where the first rotating disk is connected to the rotor shaft to an outer end of the first rotating disk of the one or more fixed disks.

2. The vacuum pump of claim 1.

7. In a radial direction perpendicular to the axial direction, The inner end of the inflow guide portion is disposed between 40% and 60% of the distance from the rotor shaft side base end to the outer end of the first rotating disk.

7. A vacuum pump according to claim 6.

8. the inflow guide portion is configured to exert a molecular drag effect on the gas between the inflow guide portion and the first rotating disk when the one or more rotating disks rotate.

2. The vacuum pump of claim 1.

9. the inflow guide portion is provided with a spiral groove having a valley portion and a peak portion on a surface facing the first rotary disk, a distance between the valley portion of the inflow guide portion and the first rotating disk is configured to be larger than a distance between the valley portion of a first fixed disk, which is arranged opposite to the downstream side of the first rotating disk among the one or more fixed disks, and the first rotating disk.

2. The vacuum pump of claim 1.

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