Vacuum pump and inflow guide components for the vacuum pump

Abstract

In the Sigban-type exhaust mechanism, the back pressure dependence is increased while suppressing the decrease in exhaust velocity. A vacuum pump includes: a housing having an intake port; a rotor shaft disposed within the housing; one or more rotating discs rotatable with the rotor shaft; and one or more fixed discs axially opposed to each of the rotating discs, with spiral grooves having valleys and ridges on their opposing surfaces; a gas flow path is formed by the spiral grooves opposite to the rotating discs; gas introduced from the intake port is discharged by the interaction of the rotating discs and the fixed discs; characterized in that an inflow guide portion is provided on the first rotating disc, closer to the intake port side than the rotating discs, to guide the inflow of the gas.

Description

Technical Field

[0001] This invention relates to a vacuum pump and an inflow guide component for the vacuum pump. Background Technology

[0002] As background technology in this field, there is Japanese Patent Application Publication No. 2015-102076 (Patent Document 1). In this publication, it is stated that "the vacuum pump according to an embodiment of the present invention is a composite vacuum pump comprising a vacuum pump component that effectively connects a pipe with an exhaust function to another pipe and a Sigban-type exhaust mechanism. The fixed circular plate forms a spiral groove (spiral groove) having a mountain and a valley, and has a protrusion (protrusion) on either the inner diameter portion facing the rotating cylinder (rotating body cylindrical portion) or the inner diameter portion of the fixed cylinder disposed on the outer periphery. Furthermore, the rotating circular plate forms a spiral groove having a mountain and a valley, and has a protrusion (protrusion) on either the outer diameter portion of the rotating cylinder disposed on the inner periphery or the outer diameter portion of the rotating circular plate facing the spacer" (see abstract of the specification).

[0003] Existing technical documents Patent documents Patent document 1: Japanese Patent Application Publication No. 2015-102076. Summary of the Invention

[0004] The problem that the invention aims to solve Patent Document 1 discloses a structure in which a protrusion is provided in the foldback flow path of a Sigban-type (also known as a Sigban) molecular pump to connect the pipe on the intake side, which has an exhaust function, to the pipe on the exhaust side. Patent Document 1 describes how such a structure can improve exhaust efficiency.

[0005] Furthermore, it is known that the Sigban-type exhaust system exhibits excellent back pressure dependence, which can be improved, for example, by combining it with other exhaust systems or increasing its number of stages. This "back pressure dependence" refers to an indicator of the degree to which back pressure (exhaust port pressure) affects suction pressure (intake port pressure) in a vacuum exhaust system; the lower this effect, the better the back pressure dependence. However, in the Sigban-type exhaust system, there is a contradiction: as back pressure dependence increases, exhaust velocity decreases.

[0006] Methods for solving problems To address the aforementioned issues, for example, the structure described in the claims may be employed.

[0007] This application includes several means for solving the above-mentioned problems, but one example is a vacuum pump comprising: a housing having an intake port; a rotor shaft disposed within the housing; one or more rotating discs capable of rotating together with the rotor shaft; and one or more fixed discs axially opposed to each of the one or more rotating discs, with spiral grooves having valleys and peaks provided on the opposing surfaces; a gas flow path is formed by means of the spiral grooves opposite to the one or more rotating discs; and gas introduced from the intake port is discharged by means of the interaction between the one or more rotating discs and the one or more fixed discs; characterized in that an inflow guide portion for guiding the inflow of the gas is provided on the first rotating disc closer to the intake port side than the one or more rotating discs.

[0008] Invention Effects According to the present invention, in the Sigban-type exhaust mechanism, it is possible to improve back pressure dependence while suppressing the decrease in exhaust velocity.

[0009] Other issues, structures, and effects not mentioned above become clear through the following description of the implementation methods. Attached Figure Description

[0010] Figure 1 This is an example of a longitudinal sectional view of a turbomolecular pump.

[0011] Figure 2 This is an example of a circuit diagram for an amplifier circuit used to control the rotor shaft of a turbomolecular pump.

[0012] Figure 3 This is an example of a time graph representing control when the current command value is greater than the detected value.

[0013] Figure 4 This is an example of a time graph representing control when the current command value is smaller than the detected value.

[0014] Figure 5 This is an example of a longitudinal sectional view of another turbomolecular pump.

[0015] Figure 6 yes Figure 5 A magnified view of a portion of the image.

[0016] Figure 7 yes Figure 5 A rough cross-sectional view along line VII-VII.

[0017] Figure 8 This is an example of a top view of a fixed circular plate.

[0018] Figure 9 This is an example of a bottom view of a fixed circular plate.

[0019] Figure 10 This is an example of a longitudinal sectional view of a fixed circular plate.

[0020] Figure 11 It is a graph that roughly shows the relationship between the suction pressure and back pressure of the exhaust mechanism of the Siegban type.

[0021] Figure 12 This is a longitudinal sectional view of a turbomolecular pump according to one embodiment.

[0022] Figure 13 yes Figure 12 A magnified view of a portion of the image.

[0023] Figure 14 This is an example of a bottom view of the inflow guide section according to one embodiment.

[0024] Figure 15 yes Figure 14 XV-XV line sectional view.

[0025] Figure 16 This is a simplified schematic diagram illustrating the shape of the mountain section flowing into the guide section.

[0026] Figure 17 This is a graph showing the simulation results of the relationship between the inner radius of the inflow guide section and the inlet pressure of the Sigban section.

[0027] Figure 18 This is an example of a partial cross-sectional view of the inflow guide section in relation to other embodiments. Detailed Implementation

[0028] The following description, based on the accompanying drawings, describes a vacuum pump according to one embodiment. The X-axis, Y-axis, and Z-axis are shown in some of the drawings, each depicted in a common direction. However, these are merely directions for ease of explanation and do not limit the configuration of the vacuum pump. Furthermore, for the same component, there are instances where the component is given a reference numeral in one drawing but omitted in others.

[0029] <Basic Structure of a Turbomolecular Pump> Figure 1 This illustrates the basic structure of a turbomolecular pump 100, an example of a vacuum pump. The turbomolecular pump 100... Figure 1 Above this becomes the upstream (intake) side, where the intake port 101 is connected, for example, to the vacuum chamber of an object device such as a semiconductor manufacturing apparatus (not shown). Furthermore, the turbomolecular pump 100... Figure 1 The lower part becomes the downstream (exhaust) side, and an auxiliary pump (not shown) is connected to the exhaust port 133, for example. This turbomolecular pump 100, in addition to... Figure 1In addition to the vertical position shown, it can also be used in the inverted vertical position, horizontal position, and inclined position.

[0030] exist Figure 1 The image shows a longitudinal sectional view of the turbomolecular pump 100. Figure 1 In this turbomolecular pump 100, an intake port 101 is formed at the upper end of a cylindrical outer cylinder 127. Furthermore, a rotating body 103 is located inside the outer cylinder 127. This rotating body 103 has multiple rotating blades 102 (102a, 102b, 102c…) radially and in multiple segments around its periphery, used to draw and expel gas. A rotor shaft 113 is mounted at the center of this rotating body 103. This rotor shaft 113 is suspended in the air and its position is controlled, for example, by a five-axis controlled magnetic bearing. The rotating body 103 is generally made of a metal such as aluminum or an aluminum alloy.

[0031] Four upper radial electromagnets 104 are arranged in pairs along the X and Y axes. Four upper radial sensors 107 are provided close to and corresponding to each upper radial electromagnet 104. The upper radial sensors 107, for example, use inductive sensors with conductive windings or eddy current sensors, and detect the position of the rotor shaft 113 based on the change in inductance of the conductive windings corresponding 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 this information to the control device 200.

[0032] In this control device 200, for example, a compensation circuit with PID regulation 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. Figure 2 The amplifier circuit 150 shown (described later) excites the upper radial electromagnet 104 based on the excitation control command signal, thereby adjusting the radial position of the upper side of the rotor shaft 113.

[0033] Furthermore, the rotor shaft 113 is formed of a high-permeability material (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. This adjustment is performed independently in the X-axis and Y-axis directions respectively. In addition, the lower radial electromagnet 105 and the lower radial sensor 108 are configured in the same way as the upper radial electromagnet 104 and the upper radial sensor 107, adjusting the lower radial position of the rotor shaft 113 in the same way as the upper radial position.

[0034] Furthermore, axial electromagnets 106A and 106B are arranged to sandwich a circular metal disk 111 mounted on the lower part of the rotor shaft 113. The 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 the rotor shaft 113, and its axial position signal is sent to the control device 200.

[0035] Furthermore, in the control device 200, for example, a compensation circuit with PID regulation function generates excitation control command signals for axial electromagnets 106A and 106B based on the axial position signal detected by the axial sensor 109. The amplifier circuit 150 performs excitation control on axial electromagnets 106A and 106B based on these excitation control command signals. As a result, axial electromagnet 106A attracts metal disk 111 upward by magnetic force, and axial electromagnet 106B attracts metal disk 111 downward, thereby adjusting the axial position of rotor shaft 113.

[0036] Thus, the control device 200 appropriately adjusts the magnetic force exerted by the axial electromagnets 106A and 106B on the metal disk 111, causing the rotor shaft 113 to be magnetically levitated in the axial direction and held in space non-contactly. Furthermore, the amplifier circuit 150 that controls the excitation of these upper radial electromagnets 104, lower radial electromagnets 105, and axial electromagnets 106A and 106B will be described later.

[0037] On the other hand, the motor 121 has a plurality of magnetic poles arranged circumferentially around the rotor shaft 113. Each magnetic pole is controlled by the control device 200 to drive the rotor shaft 113 to rotate via an electromagnetic force acting between the rotor shaft 113 and the control device 200. Furthermore, the motor 121 is equipped with a rotational speed sensor (not shown), such as a Hall element, a rotary transformer, or an encoder, and the rotational speed of the rotor shaft 113 is detected by means of the detection signal from the rotational speed sensor.

[0038] Furthermore, for example, a phase sensor (not shown) is mounted near the lower radial sensor 108 to detect the phase of rotation of the rotor shaft 113. In the control device 200, the detection signals from this phase sensor and the rotational speed sensor are used together to detect the position of the magnetic poles.

[0039] Multiple fixed blades 123 (123a, 123b, 123c...) are arranged with slight gaps between them and the rotating blades 102 (102a, 102b, 102c...). The rotating 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 move the molecules of the exhaust gas downward by collision. The fixed blades 123 (123a, 123b, 123c...) are made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components.

[0040] Furthermore, the fixed blade 123 is also formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and is arranged alternately with the section of the rotating blade 102 facing inward toward the outer cylinder 127. Moreover, the outer peripheral end of the fixed blade 123 is supported in a state of being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c...).

[0041] The fixed blade spacer 125 is an annular component, made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed blade spacer 125 with a slight gap. A base portion 129 is provided at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129, communicating with the outside. Exhaust gas entering the intake port 101 from the chamber (vacuum chamber) side and being transferred to the base portion 129 is conveyed to the exhaust port 133.

[0042] Furthermore, according to the application of the turbomolecular pump 100, a threaded spacer 131 is provided between the lower part of the fixed blade spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical component made of metals such as aluminum, copper, stainless steel, iron, or alloys composed of these metals, and has multiple helical threaded grooves 131a engraved on its inner circumferential surface. The helical direction of the threaded grooves 131a is the direction in which the molecules of the discharged gas are moved towards the exhaust port 133 when they move in the rotational direction of the rotating body 103. At the lowest part of the rotating body 103, which is continuous with the rotating blades 102 (102a, 102b, 102c...), a cylindrical part 102d hangs down. The outer circumferential surface of the cylindrical part 102d is cylindrical and extends toward the inner circumferential surface of the threaded spacer 131, approaching the inner circumferential surface of the threaded spacer 131 with a predetermined gap. The exhaust gas, which is moved to the threaded groove 131a by the rotating blade 102 and the fixed blade 123, is guided by the threaded groove 131a and conveyed to the base portion 129.

[0043] The base portion 129 is a disc-shaped component that forms the base of the turbomolecular pump 100, and is generally made of metals such as iron, aluminum, or stainless steel. Since the base portion 129 physically holds the turbomolecular pump 100 and also functions as a heat conduction path, it is desirable to use metals such as iron, aluminum, or copper that have rigidity and high thermal conductivity.

[0044] In this structure, if the rotating blade 102 and the rotor shaft 113 are driven to rotate by the motor 121, the exhaust gas is drawn from the chamber through the intake port 101 by the action of the rotating blade 102 and the fixed blade 123. The rotational speed of the rotating blade 102 is typically 20,000 rpm to 90,000 rpm, and the circumferential speed at the end of the rotating blade 102 reaches 200 m / s to 400 m / s. The exhaust gas drawn in from the intake port 101 is transferred to the base portion 129 between the rotating blade 102 and the fixed blade 123. At this time, the temperature of the rotating blade 102 rises due to frictional heat generated when the exhaust gas contacts the rotating blade 102, heat conduction generated by the motor 121, etc., but this heat is transferred to the fixed blade 123 side by radiation or conduction by the gas molecules of the exhaust gas.

[0045] The fixed blade spacers 125 are joined together on the outer periphery to transfer the heat received by the fixed blade 123 from the rotating blade 102, the frictional heat generated when the exhaust gas comes into contact with the fixed blade 123, and so on to the outside.

[0046] Furthermore, in the above description, it was assumed that the threaded spacer 131 was disposed on the outer periphery of the cylindrical portion 102d of the rotating body 103, and that a threaded groove 131a was engraved on the inner peripheral surface of the threaded spacer 131. However, there are also cases where, conversely, a threaded groove is engraved on the outer peripheral surface of the cylindrical portion 102d, and a spacer with a cylindrical inner peripheral surface is disposed around it.

[0047] Furthermore, depending on the application of the turbomolecular pump 100, there are also cases where the electrical assembly is surrounded by a stator column 122, and the stator column 122 is maintained at a predetermined pressure by means of a purge gas, so that the gas drawn from the intake port 101 does not intrude into the electrical assembly, which is composed of an upper radial electromagnet 104, an upper radial sensor 107, a motor 121, a lower radial electromagnet 105, a lower radial sensor 108, axial electromagnets 106A and 106B, an axial sensor 109, etc.

[0048] In this case, a pipe (not shown) is provided on the base portion 129, through which purge gas is introduced. 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 circumferential cylindrical portion of the rotating blade 102.

[0049] Here, the turbomolecular pump 100 requires the determination of its specific model and control based on its inherent parameters (e.g., characteristics corresponding to the model). To store these control parameters, the turbomolecular pump 100 includes an electronic circuit section 141 within its main body. The electronic circuit section 141 comprises a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing it, and a mounting substrate 143 for mounting them. This electronic circuit section 141 is housed below, for example, a rotational speed sensor (not shown) near the center of the base section 129 constituting the lower part of the turbomolecular pump 100, and is sealed by an airtight bottom cover 145.

[0050] Incidentally, in the semiconductor manufacturing process, the process gas introduced into the chamber contains gases that become solid if their pressure becomes higher than a predetermined value or their temperature becomes lower than 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, during the process gas's journey from the intake port 101 to the exhaust port 133, its pressure becomes higher than a predetermined value or its temperature becomes lower than a predetermined value, the process gas becomes solid and adheres to and accumulates inside the turbomolecular pump 100.

[0051] For example, when SiCl4 is used as a process gas in an Al etching apparatus, the vapor pressure profile shows that under low vacuum (760 [torr] ~ 10... －2 At low temperatures (approximately 20 °C), solid products (e.g., AlCl3) precipitate and accumulate inside the turbomolecular pump 100. Consequently, if process gas precipitates accumulate inside the turbomolecular pump 100, this accumulation narrows the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. Furthermore, the aforementioned products are prone to solidification and adhesion in the high-pressure areas near the exhaust port 133 and the threaded spacer 131.

[0052] Therefore, in order to solve this problem, conventionally a heater (not shown) and an annular water-cooling pipe 149 are wound 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, for example. Based on the signal of the temperature sensor, the heating of the heater and the cooling of the water-cooling pipe 149 are controlled (hereinafter referred to as TMS; TMS; Temperature Management System) to maintain the temperature of the base portion 129 at a certain high temperature (set temperature).

[0053] Next, regarding the turbomolecular pump 100 configured in this way, 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. Figure 2 The diagram below shows the circuit diagram of amplifier circuit 150.

[0054] exist Figure 2 In this configuration, one end of the electromagnet winding 151, which constitutes the upper radial electromagnet 104, is connected to the positive terminal 171a of the power supply 171 via transistor 161, and the other end is connected to the negative terminal 171b of the power supply 171 via current detection circuit 181 and transistor 162. Furthermore, transistors 161 and 162 are so-called power MOSFETs, having a structure in which a diode is connected between its source and drain.

[0055] At this time, the cathode terminal 161a of transistor 161 is connected to the positive terminal 171a, and the anode terminal 161b is connected to one end of electromagnet winding 151. Furthermore, the cathode terminal 162a of transistor 162 is connected to current detection circuit 181, and the anode terminal 162b is connected to negative terminal 171b.

[0056] On the other hand, the cathode terminal 165a of the diode 165 used for current regeneration is connected to one end of the electromagnet winding 151, and its anode terminal 165b is connected to the negative terminal 171b. Similarly, the cathode terminal 166a of the diode 166 used for current regeneration is connected to the positive terminal 171a, and its anode terminal 166b is connected to the other end of the electromagnet winding 151 via the current detection circuit 181. Furthermore, the current detection circuit 181 is, for example, composed of a Hall effect current sensor and a resistive element.

[0057] The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, with five-axis magnetic bearings and a total of 10 electromagnets 104, 105, 106A, and 106B, each electromagnet is configured with the same amplifier circuit 150, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0058] Furthermore, the amplifier control circuit 191 is, for example, composed of a digital signal processor (DSP) unit (not shown) of the control device 200, which switches the transistors 161 and 162 on / off.

[0059] The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (the signal reflecting this current value is called the current detection signal 191c) with a predetermined current command value. Then, based on the comparison result, it determines the magnitude of the pulse width (pulse width times Tp1 and Tp2) generated within one control cycle Ts, which is the PWM control cycle. As a result, gate drive signals 191a and 191b with this pulse width are output from the amplifier control circuit 191 to the gate terminals of transistors 161 and 162.

[0060] Furthermore, when the rotating body 103 passes through a resonance point during accelerated operation or when interference occurs during constant-speed operation, position control of the rotating body 103 under high speed and strong force is required. Therefore, a voltage of approximately 50V is used as the power supply 171 to enable a rapid increase (or decrease) in the current flowing through the electromagnet winding 151. In addition, a capacitor (not shown) is usually connected between the positive terminal 171a and the negative terminal 171b of the power supply 171 to stabilize the power supply 171.

[0061] In this structure, if both transistors 161 and 162 are turned on, the current flowing in the electromagnet winding 151 (hereinafter referred to as electromagnet current iL) increases; if both are turned off, the electromagnet current iL decreases.

[0062] Furthermore, by setting one of transistors 161 and 162 to conduct and the other to cut off, a freewheeling current is maintained. Moreover, by allowing this freewheeling current to flow through the amplifier circuit 150, hysteresis losses in the amplifier circuit 150 can be reduced, thus lowering the overall power consumption of the circuit. Furthermore, by controlling transistors 161 and 162 in this way, high-frequency noise such as high-order harmonics generated in the turbomolecular pump 100 can be reduced. Furthermore, by measuring this freewheeling current using the current detection circuit 181, the electromagnet current iL flowing in the electromagnet winding 151 can be detected.

[0063] That is, when the detected current value is smaller than the current command value, such as Figure 3 As shown, transistors 161 and 162 are turned on only once during the control period Ts (e.g., 100 μs) for a duration equivalent to the pulse width time Tp1. Therefore, the electromagnet current iL during this period increases toward the current value iLmax (not shown) that can flow from the positive terminal 171a to the negative terminal 171b via transistors 161 and 162.

[0064] On the other hand, if the detected current value is larger than the current command value, such as Figure 4As shown, transistors 161 and 162 are turned off only once during the control cycle Ts for a duration equivalent to the pulse width time Tp2. Therefore, the electromagnet current iL during this period decreases toward the current value iLmin (not shown) that can be regenerated from the negative terminal 171b to the positive terminal 171a via diodes 165 and 166.

[0065] Furthermore, in both cases, one of transistors 161 and 162 is turned on after the pulse width times Tp1 and Tp2 have elapsed. Therefore, during this period, a continuous current is maintained in the amplifier circuit 150.

[0066] In the turbomolecular pump 100 described above, for example, the main outer cylinder 127 and the base portion 129 are combined to form a housing (hereinafter referred to as the "casing"). Furthermore, the exhaust mechanism provided within the casing can be divided into a turbomolecular pump mechanism portion consisting of rotating blades 102 and fixed blades 123, and a slot exhaust mechanism portion consisting of a cylindrical portion 102d and threaded spacers 131. The slot exhaust mechanism portion is not limited to being composed of a cylindrical portion 102d and threaded spacers 131; for example, it can also be composed of a Sigban-type exhaust mechanism portion 301 (described later) or a Holwick-type exhaust mechanism portion. The exhaust mechanism of the turbomolecular pump 100 can also be composed of any one or more slot exhaust mechanism portions.

[0067] <Sigban-type exhaust system> Next, based on Figures 5 to 11 Other forms of the aforementioned venting mechanism will be described. Figure 5 This is a longitudinal sectional view of the turbomolecular pump 100A. Figure 6 From Figure 5 The rotation axis of the rotor shaft 113 is shown in a partially enlarged view on the right. The turbomolecular pump 100A is equipped with the turbomolecular pump mechanism 201 and the Sigma-Aldrich type exhaust mechanism 301 described above as a slot exhaust mechanism. The Sigma-Aldrich type exhaust mechanism 301 is arranged in a spatially continuous manner in the next section (immediately downstream side) of the turbomolecular pump mechanism 201.

[0068] Figure 5 The exhaust mechanism is a Siegban-type exhaust mechanism 301, which is similar to... Figure 1 Although they differ, the other basic structures are the same. Therefore, repeated descriptions of the structure and function of the common parts are omitted. Depending on the application, the turbomolecular pump 100A may also have other slotted exhaust mechanisms, such as a Holwick type exhaust mechanism (not shown), in the section immediately downstream of the Siegban type exhaust mechanism 301.

[0069] The Sigban-type exhaust mechanism 301 is a Sigban-type exhaust mechanism, which is generally composed of a rotating circular plate 320 (320a, 320b) and a fixed circular plate 330 (330a). The rotating circular plate 320 (320a, 320b) and the fixed circular plate 330 (330a) are made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components.

[0070] The rotating circular plates 320 (320a, 320b) are generally annular plates integrally formed on the outer periphery of the cylindrical rotating body 103. Each rotating circular plate 320a, 320b is coaxial with the rotating body 103 and axially separated. The rotating circular plates 320 (320a, 320b) are driven to rotate by a motor 121 and rotate in the same direction (rotation direction) as the rotating body 103, rotating blades 102, etc. Figure 6 In the example, the Sigban-type exhaust mechanism 301 has two (two-section) rotating discs 320a and 320b, but depending on the combination with the fixed disc, the rotating discs can be one (single section) or three (three sections) or more. Hereinafter, the rotating disc 320 arranged on the side closest to the intake port 101 among the one (single section) or multiple (multi-section) rotating discs 320 is referred to as the first rotating disc 320a.

[0071] The fixed circular plate 330 (330a) is generally an annular plate, integrally assembled into the housing. The fixed circular plate 330 (330a) can be composed of a single annular plate, or it can be composed of multiple segmented pieces, for example, divided into arc shapes. The fixed circular plate 330a is positioned between the two rotating circular plates 320a and 320b with a predetermined gap. Figure 5 In the example, the Sigban-type exhaust mechanism 301 has one (segment) fixed circular plate 330a, but depending on the combination with the rotating circular plate, there may be two (segments) or more fixed circular plates. Hereinafter, the fixed circular plate arranged on the side closest to the intake port 101 among the one (segment) or multiple (multi-segment) fixed circular plates 330 is referred to as the first fixed circular plate 330a.

[0072] Figure 5 The fixed circular plate 330 in the Sigban-type exhaust mechanism 301 shown has one segment, and the rotating circular plate 320 has two segments. These rotating circular plates 320 and fixed circular plates 330 are arranged alternately from the intake port 101 side in the order of rotating circular plate 320 (first rotating circular plate 320a), fixed circular plate 330 (first fixed circular plate 330a), and rotating circular plate 320 (second rotating circular plate 320b).

[0073] In the Sigban-type exhaust mechanism 301, a spiral groove is provided on at least one of the opposing surfaces of the rotating circular plate 320 and the fixed circular plate 330. In this embodiment, the rotating circular plate 320 is a generally flat plate, and a spiral groove 334 is provided on both sides of the fixed circular plate 330, namely the upstream side (intake port 101 side) and the downstream side (intake port 101 side).

[0074] Figure 7 yes Figure 5 The schematic cross-sectional view along line VII-VII roughly shows the condition of the fixed circular plate 330 of the Siegban-type exhaust mechanism 301 as viewed from the intake port 101 side. Furthermore, Figures 8-10 This is an example of a top view, a bottom view, and a partial sectional view of a fixed circular plate 330. The fixed circular plate 330, for example, has a generally annular circular plate portion 331 and a protruding portion 332 extending from the circular plate portion 331 toward the rotating circular plate 320. A through hole at the center of the circular plate portion 331 is used to insert the rotating body 103, rotor shaft 113, etc. Furthermore, it is not necessarily limited to this, but in this embodiment, the fixed circular plate 330 has a generally annular fixing spacer 335 integrally formed on the outer periphery of one side of the circular plate portion 331 (here, the side facing the air intake 101) (see reference). Figure 10 (etc.). The fixed spacer 335 is a component that performs the same function as the fixed blade spacer 125 described above.

[0075] On both sides of the fixed circular plate 330, multiple hills 332 are provided in a spiral (vortex) shape. Figure 7 In the diagram, the mountain portion 332 on the upstream side of the fixed circular plate 330 is shown with a solid line, and the mountain portion 332 on the downstream side is shown with a dashed line. When the rotating circular plate rotates in the direction indicated by arrow R, the mountain portion 332 on the upstream side extends in the same direction (co-directional) as the rotation direction, from the outer (outer circumferential side) to the inner (inner circumferential side) in a radial direction orthogonal to the axial direction. Furthermore, the mountain portion 332 on the downstream side extends in the opposite direction (opposite to the upstream side) in a planar view, from the inner to the outer in a radial direction. However, as... Figure 9 As shown, the mountain part 332 of the downstream side extends in a direction in the same direction as the rotation direction (arrow R) (forward direction) as the radial direction from the inside (inner circumferential side) to the outside (outer circumferential side).

[0076] The surface of the circular plate portion 331 without the hill portion 332 becomes a valley portion 333 that is recessed relative to the hill portion 332. The hill portion 332 and the valley portion 333 form a spiral groove 334. With the help of this spiral groove 334 of the fixed circular plate 330 and the rotating circular plate 320 opposite it, a gas flow path for transferring gas is formed. In addition, the spiral groove 334 can be adjusted, for example, in terms of width and depth, so that the flow path area gradually decreases as it moves towards the downstream side.

[0077] In this Sigban-type exhaust mechanism 301, when the rotating disc 320 rotates at high speed, gas molecules present inside the spiral groove collide with the rotating disc 320, imparting momentum along the rotational direction to the gas molecules. While also colliding with the flow path wall of the gas flow path, the gas molecules are propelled towards the exhaust port 133 by the component of this momentum along the length of the spiral groove 334. This is called the molecular drag effect. Furthermore, gas molecules, for example, in… Figure 6 As indicated by the dashed line, the gas molecules are moved axially in the turbomolecular pump mechanism 201. In contrast, in the Sigban-type exhaust mechanism 301 downstream of the turbomolecular pump mechanism 201, the gas molecules are moved radially.

[0078] Specifically, in the Sigban-type exhaust mechanism 301, gas molecules move from the outer side to the inner side in a spiral gas flow path constructed on the upstream side of the fixed circular plate 330, and then move from the inner side to the outer side in a gas flow path constructed on the downstream side of the fixed circular plate 330, and are conveyed to the exhaust port 133. (Referring to...) Figure 7 The gas molecules move from the outer side to the inner side in the radial direction in the spiral gas flow path on the upstream side of the fixed circular plate 330, as indicated by the solid arrow. On the downstream side of the fixed circular plate 330, as indicated by the dashed arrow, they are moved from the inner side to the outer side in the radial direction in the gas flow path.

[0079] In addition, indicators used to describe the exhaust performance of vacuum pumps generally include "exhaust velocity," "compression performance," and "back pressure performance." These indicators are specified, for example, in Japanese Industrial Standard JIS B 8329-1:2015, and the values ​​of each indicator can be determined according to this standard. Among these indicators, "exhaust velocity" is expressed as the volume of gas passing through the suction port per unit time. Furthermore, "compression performance" is an indicator of the degree to which gas can be compressed, expressed as the ratio of the exhaust port pressure to the suction port pressure when the flow rate is 0 (zero). "Back pressure performance," as described above, is an indicator of the degree to which changes in back pressure affect the suction pressure.

[0080] Figure 11This is a graph used to illustrate the exhaust performance of a Sigban-type exhaust system, roughly showing the relationship between suction and back pressure. The back pressure (pressure at the exhaust port of the Sigban-type exhaust system) is displayed on the horizontal axis, and the suction pressure (pressure at the intake port of the Sigban-type exhaust system) is displayed on the vertical axis using a logarithmic scale. Furthermore, the unit for exhaust port pressure is [Torr], and the unit for intake port pressure (Ps) in this case is typically [mTorr].

[0081] Because the exhaust velocity of a vacuum pump varies depending on the vacuum level, an auxiliary pump is typically connected to the exhaust (downstream) side for use in a region suitable for the pump's vacuum level. Here, with respect to the vacuum pump at the desired vacuum level, the pressure (back pressure) on the auxiliary vacuum side, provided by the auxiliary pump, gradually increases at a given flow rate. Thus, as... Figure 11 As shown in (a), the vacuum level (suction pressure) on the suction side remains almost unchanged up to a certain pressure, but deteriorates sharply if this pressure is exceeded. In a vacuum pump, the larger the pressure range that maintains the suction pressure at a certain back pressure (refer to "good" in the diagram), the smaller the influence of back pressure on the suction pressure; in other words, the better the back pressure dependence. Furthermore, the faster the exhaust velocity, such as... Figure 11 As shown in (b), the curve representing the relationship between suction pressure and back pressure shifts further down (refer to "good" in the figure).

[0082] Here, it is known that the Sigban-type exhaust mechanism has higher back pressure performance compared to other exhaust mechanisms. To further improve this back pressure performance, increasing the gas flow path length, i.e., increasing the number of sections in the Sigban-type exhaust mechanism section 301, is effective. Increasing the gas flow path length is also effective in improving compression performance. However, if the number of sections in the Sigban-type exhaust mechanism section 301 is increased, then... Figure 11 As shown in (c), the curve representing the relationship between suction pressure and back pressure shifts to the upper right (refer to the "multi-segment" in the figure). In other words, there is a contradiction: if you want to improve back pressure performance, the exhaust velocity decreases.

[0083] <Inflow Guidance Section> Next, based on Figures 12 to 18 The turbomolecular pump 300 of this technology will be described. Figure 12 This is a longitudinal sectional view of a turbomolecular pump 300 according to one embodiment. Figure 13 This is a partial enlarged view. The turbomolecular pump 300 has an inflow guide 310 on the downstream side of the turbomolecular pump mechanism 201 and the upstream side immediately before the Sigban-type exhaust mechanism 301. Figure 12 In addition to having an inflow guide section 310, it also has Figure 5 For parts that are the same, repeated descriptions of their structure and function are omitted.

[0084] The inflow guide section 310 is a component that guides the flow of gas flowing into the Siegban-type exhaust mechanism section 301. The inflow guide section 310 is positioned upstream of the first rotating circular plate 320a of the Siegban-type exhaust mechanism section 301 with a predetermined gap. The inflow guide section 310 is generally an annular plate and is a static component integrally assembled into the housing. The inflow guide section 310 is made of, for example, metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components.

[0085] Figure 14 This is an example of a bottom view (viewed from the exhaust port 133 side) of the inflow guide section 310. Figure 15 It is a cross-sectional view along the XV-XV line. Figure 16 This is a schematic diagram illustrating the shape of the mountain section that flows into the guide section.

[0086] The inflow guide section 310 includes a guide circular plate 311 and a mountain section 312. However, it is not necessarily limited to this, but in this embodiment, the inflow guide section 310 has an integrally formed, generally annular, fixing spacer 315 on the outer periphery of the opposing surface 311a (the surface on the exhaust port 133 side) opposite to the first rotating circular plate 320a. The fixing spacer 315 is a component that performs the same function as the fixing blade spacer 125 described above.

[0087] The guiding circular plate 311 is a generally annular plate. This will be explained in detail later, but the inner diameter of the guiding circular plate 311 is typically configured to be larger than the inner diameter of the first fixed circular plate 330a. Furthermore, for example, the guiding circular plate 311 and the first rotating circular plate 320a are configured to exert a molecular dragging effect when the first rotating circular plate 320a rotates. The surface of the guiding circular plate 311 can be either flat or, for example, as shown in the image. Figure 15 The tilt is set in such a way that the thickness gradually increases from the center to the outer periphery. The rotating body 103, rotor shaft 113, etc. are inserted through the through hole in the center of the guide plate 311.

[0088] The mountain portion 312 is integrally provided relative to the guide circular plate 311, protruding from the guide circular plate 311 toward the first rotating circular plate 320a. The mountain portion 312 is provided on the opposing surface 311a of the guide circular plate 311 opposite to the first rotating circular plate 320a, and there is no surface provided on the opposite side (i.e., the upstream side). In this embodiment, the mountain portion 312 is a strip-shaped plate with a generally rectangular cross-sectional shape. In this embodiment, the guide circular plate 311 is provided with a plurality of mountain portions 312, but the number of mountain portions 312 is not particularly limited and can be one or more.

[0089] For example, mountain section 312 Figure 14As shown, it is generally spiral-shaped (vortex-shaped). The mountain section 312 extends in the same direction (co-directional) as the first rotating circular plate 320a rotates in the direction indicated by arrow R, moving radially from the inside to the outside in the same direction as the direction of rotation. More specifically, for example, as... Figure 16 (a) ~ Figure 16 As shown in (c), the mountain part 312 is configured such that, relative to the radial direction orthogonal to the rotation axis of the rotating body 103, the outer periphery is inclined in the same direction as the rotation direction (arrow R), and the inner periphery is inclined in the opposite direction to the rotation direction.

[0090] A mountain section 312, for example, can also be like Figure 16 (a) shows a straight line shape. Furthermore, a hill 312 can, for example, be formed as follows: Figure 16 (b) shows a zigzag shape with bends in one or more places. Furthermore, a mountain section 312 can, for example, be formed as follows: Figure 16 (c) shows a smoothly curved shape. A mountain 312 can be any combination of shapes, as long as it is oriented in the same direction as the rotation direction from the inside to the outside in the radial direction. When multiple mountains 312 are provided on a guide plate 311, each mountain 312 can be the same shape or partially or completely different from each other.

[0091] The portion of the opposite surface 311a of the guide plate 311 that does not have a mountain 312 becomes a valley 313 that is relatively concave relative to the mountain 312 (see reference). Figure 15 The mountain section 312 and valley section 313 form a spiral groove 314. The space surrounded by the spiral groove 314 of the guide plate 311 and the first rotating plate 320a opposite to it can become an inlet gas flow path mainly used to introduce gas into the Siegban-type exhaust mechanism section 301.

[0092] By providing an inflow guide 310 at the front section (immediately upstream side) of the Sigban-type exhaust mechanism section 301, gas flowing into the Sigban-type exhaust mechanism section 301 from the outside of the first rotating disc 320a is moved from the inner side to the outer side in the radial direction by means of a drag effect. At this time, gas molecules flowing into the inflow guide 310 are suppressed from returning from the inner side to the outer side in the radial direction by means of the hill 312. As a result, it is possible to suppress the decrease in exhaust velocity in the Sigban-type exhaust mechanism section 301 while improving back pressure dependence. Hereinafter, the mechanism by which the inflow guide 310 suppresses the decrease in exhaust velocity in the Sigban-type exhaust mechanism section 301 of the present invention will be explained in conjunction with verification based on thermofluid analysis.

[0093] <Fluid Analysis> Using thermofluid analysis, the changes in exhaust characteristics were evaluated with and without the inflow guide section 310 combined on the upstream side of the Sigban-type exhaust mechanism section 301 in the vacuum pump. Furthermore, regarding the case where the inflow guide section 310 was combined, the exhaust characteristics were also evaluated when the dimensions of the inflow guide section 310 (guide disc) were changed. Commercially available thermofluid analysis software was used in the analysis.

[0094] An analytical model of the flow path of the Siegfried exhaust system was used to simulate the exhaust mechanism, based on... Figure 6 and Figure 12 The CAD model of the turbomolecular pump 300 shown was created by extracting the gas flow path from the position passing through the turbomolecular pump mechanism 201 to the position passing through the sigban-type exhaust mechanism 301. In addition, in order to evaluate the exhaust characteristics in the sigban-type exhaust mechanism 301 in more detail, the sigban-type exhaust mechanism 301 in the analytical model is set as a multi-segment sigban with four rotating circular plates 320 and three fixed circular plates 330.

[0095] Then, the pressure (i.e., suction pressure) at the front section of the Sigban-type exhaust mechanism was calculated, with the pressure (i.e., back pressure) at the location of the Sigban-type exhaust mechanism set to a predetermined pressure. The Reynolds Averaged Navier-Stokes (RANS) model was used in the turbulence analysis, and the k-ε model was applied to evaluate the Reynolds stress, simulating the pressure distribution of the compressed fluid N2 within the flow path.

[0096] Furthermore, the suction pressure was calculated for the case where the inflow guide 310 is not provided (basic), and for the case where the inflow guide 310 is provided and its inner diameter is varied in three ways (No. 1 to 3). Hereinafter, with reference to... Figure 13 The method of expressing the change in the inner diameter of the inflow guide 310 will be explained.

[0097] <Reference for Rotating Circular Plate> When the inner diameter of the inflow guide 310 is varied, its shape can be represented from a variety of perspectives. As an indicator, the end 316 on the inner circumferential side of the inflow guide 310 (see reference...) Figure 13 The position of the gas in the radial direction relative to the opposing first rotating circular plate 320a is indicated by this. This is because it is conceivable that the inflow guide section 310 can properly guide the gas toward the Sigban-type exhaust mechanism section 301 by means of the molecular drag effect generated between it and the first rotating circular plate 320a. Furthermore, it is conceivable that the momentum imparted to the gas molecules is related to the overlap ratio between the inflow guide section 310 and the first rotating circular plate 320a.

[0098] Furthermore, in this fluid analysis, since the shapes of the multiple rotating circular plates 320 (320a...) in the analytical model are essentially the same, the following description will be based on the rotating circular plate 320. When multiple rotating circular plates 320 (320a...) are provided with different shapes, the term "rotating circular plate 320" in the following description can be read as "the first rotating circular plate 320a".

[0099] In this case, for example, Figure 13 As shown, the position (root) where the rotating circular plate 320 connects to the rotating body 103 is defined as the base end portion 321 of the rotating circular plate 320, and is expressed by the proportion of the inner circumferential end portion 316 of the inflow guide portion 310 relative to the base end portion 321 of the rotating circular plate 320. Furthermore, the outer circumferential end portion of the rotating circular plate 320 is defined as the outer circumferential end portion 322. The base end portion 321 of the rotating circular plate 320 is located at a radius (hereinafter, for convenience, referred to as "the inner circumferential radius R of the rotating circular plate 320") away from the center of the rotating circular plate 320 and the rotating body 103. RI The dimension L of the rotating circular plate 320 in the radial direction is... R1 The width of the ring is given by the following formula: L R1 =R RO -R RI Indicated by RRO. Here, RRO is the radius of the outer periphery of the rotating circular plate 320, which is the dimension from the center of the rotating circular plate 320 to the outer periphery end 322.

[0100] Next, the inner circumferential end 316 of the inflow guide 310 is located at a distance from the center of the inflow guide 310 from the inner circumferential radius R of the inflow guide 310. GI Therefore, the dimension L from the base end 321 of the rotating circular plate 320 to the inner circumferential end 316 of the inflow guide portion 310 is... G1 The radius R of the inner circumference of the inflow guide 310 is... GI Subtract the inner circumference radius R of the rotating circular plate 320. RI The obtained dimension is given by the following formula: L G1 =R GI -R RI express.

[0101] Based on the above, the position of the inner peripheral end 316 of the inflow guide 310 relative to the distance from the base end 321 of the rotating circular plate 320 can be expressed by the following formula.

[0102] The position of the inner peripheral end 316 of the inflow guide 310 = (Dimension L from base end 321 to inner circumferential end 316) G1 ) ÷ (the radial dimension L of the rotating circular plate 320) R1 )×100 = (R) GI -R RI ) / (R RO -R RI )×100.

[0103] If the position of the inner circumferential end 316 of the inflow guide 310 in the three analytical models is represented based on such a rotating circular plate reference, then it becomes Simulation No. 1: 26%, Simulation No. 2: 57%, and Simulation No. 3: 80%. In addition, the larger the value of this index, the larger the inner diameter (or inner circumferential radius) of the inflow guide 310 becomes, and the smaller the overlap ratio with the rotating circular plate 320 becomes.

[0104] <Flow Path Region Reference> On the other hand, other indicators representing the shape of the inflow guide section 310 could be conceived not to be based on the first rotating circular plate 320a, but rather on the region where the flow path expands. This is because, for example, Figure 13 As shown, the dimension L for the return flow path is ensured between the outer peripheral end 322 of the rotating circular plate 320 and the fixed spacers 315 and 335. R2 In the exhaust characteristics brought about by the Siegban-type exhaust mechanism 301, the size L of such a return flow path is important. R2 (L) G3 L S2 It is reasonable to consider this.

[0105] Therefore, the "dimensional L in the radial direction of the rotating circular plate 320" in the aforementioned rotating circular plate reference can be used instead. R1 (Width of the annulus) is used instead of "the radial dimension L of the flow path region". G2 Here, the flow path region refers to the area in the Sigban-type exhaust mechanism 301 that can serve as a gas flow path, which is the region in the radial direction from the base end 321 of the rotating circular plate 320 to the base ends 317 and 337 of the inflow guide 310 or the fixed circular plate 330. The base end 317 of the inflow guide 310 is the position where the guide circular plate 311 is connected to the fixed spacer 315 (the position where the guide circular plate 311 protrudes from the inner circumferential surface of the fixed spacer 315). The base end 337 of the fixed circular plate 330 is the position where the circular plate portion 331 is connected to the fixed spacer 335 (the position where the circular plate portion 331 protrudes from the inner circumferential surface of the fixed spacer 335).

[0106] The radial dimension of the flow path region is given by the following formula: L G2 =R GO -R RIIndicated. Here, RGO is the outer circumferential radius of the guide plate 311 of the inflow guide section 310, which is the dimension from the center of the inflow guide section 310 to the base end 317 (i.e., excluding the fixed spacer 315 portion). Furthermore, the radial dimension of the flow path region can also be expressed, for example, by the following formula: L G2 =R SO -R RI Indicated. Here, R SO It is the outer circumferential radius of the circular plate portion 331 of the fixed circular plate 330, which is the dimension from the center of the fixed circular plate 330 to the base end portion 337 (i.e., excluding the fixed spacer 335 portion).

[0107] Furthermore, the position of the inner peripheral end 316 of the inflow guide 310 relative to the flow path region in the radial direction can be represented by the following formula.

[0108] The position of the inner peripheral end 316 of the inflow guide 310 = (the dimension L from the base end 321 to the inner peripheral end 316) G1 ) ÷ (the radial dimension L of the flow path region) G2 )×100 = (R) GI -R RI ) / (R GO -R RI )×100.

[0109] If the position of the inner circumferential end 316 of the three simulated inflow guide sections 310 is represented by such a flow path region reference, then the values ​​are: Simulation No. 1: 25%, Simulation No. 2: 55%, and Simulation No. 3: 78%. The larger the value of this index, the larger the inner diameter (or inner circumferential radius) of the inflow guide section 310, and the smaller the overlap ratio with the rotating circular plate 320.

[0110] <Simulation Results> Simulation results of the pressure distribution of the compressed fluid N2 within the flow path show that, by combining the inflow guide section 310 (No. 1-3) with the front section of the Sigban-type exhaust mechanism section 301, the overall pressure in the front section of the Sigban-type exhaust mechanism section 301 is reduced compared to the case without the inflow guide section 310 (baseline). Furthermore, it is found that in the case without the inflow guide section 310 (baseline), the pressure in the front section of the Sigban-type exhaust mechanism section 301 is approximately uniform; in contrast, when the inflow guide section 310 is provided (No. 1-3), a larger pressure variation occurs in the front section of the Sigban-type exhaust mechanism section 301. This pressure variation is particularly evident within the inflow guide section 310.

[0111] This can be attributed to the following reasons. For example, such as... Figure 13 , Figure 14As shown, if the rotating disc 320 rotates in a predetermined direction of rotation (arrow R) during the operation of the turbomolecular pump 300, the gas fluid is guided in the inlet gas flow path between the hills 312 of the inlet guide 310 at the front section of the Sigban-type exhaust mechanism section 301, where the inlet guide 310 is provided. The gas fluid moves spirally from the inner side to the outer side in the radial direction along the inlet gas flow path. The gas fluid collides with the inner circumferential surface of the fixed spacer 315 at the end of the outer circumferential side of the inlet gas flow path, and a portion of it is folded back towards the downstream side of the inlet gas flow path and delivered to the Sigban-type exhaust mechanism section 301. Moreover, another portion moves towards the inner side in the radial direction within the inlet gas flow path. However, the further movement of the gas fluid that is about to return towards the inner side in the radial direction is hindered by the presence of the hills 312 of the inlet guide 310.

[0112] Because the hill 312 of the inflow guide 310 is inclined in a manner that the further outward it is in the radial direction, the more it is inclined in the direction of rotation (arrow R), it promotes the outward flow of gas fluid in the radial direction and hinders the movement of gas fluid in the radial direction inward. As a result, it is conceivable that within the inflow guide 310, a region with relatively lower gas fluid pressure is formed on the radially inner side of the hill 312, and a region with relatively higher gas fluid pressure is formed on the radially outer side of the hill 312. Furthermore, it is conceivable that the overall pressure in the space further upstream of the inner circumference of the inflow guide 310 is reduced compared to the case where the inflow guide 310 is not provided (reference).

[0113] In this way, the pressure in the space upstream of the inflow guide section 310 and the Sigban-type exhaust mechanism section 301 (i.e., the suction pressure of the Sigban-type exhaust mechanism section 301) is reduced, meaning that... Figure 11 (b) The exhaust velocity of the Sigban-type exhaust mechanism 301 is increased. For example, in the space upstream of the inflow guide 310 and the Sigban-type exhaust mechanism 301, the density of gas molecules decreases, and the gas molecules can be discharged at a higher speed by means of the drag effect. As a result, for example in Figure 11 In the graph of (c), even the multi-segment Sigban type exhaust mechanism 301 can keep the curve representing the relationship between suction pressure and back pressure on the lower side, thus taking into account both the improvement of back pressure performance and the improvement of exhaust speed.

[0114] exist Figure 17The diagram shows the relationship between the shape of the inflow guide section (rotating circular plate reference) and the suction pressure of the Sigban-type exhaust mechanism section 301 obtained from simulation results. Furthermore, the suction pressure of the Sigban-type exhaust mechanism section 301 represents a value (%) normalized to 100 for the case without an inflow guide section (reference). While also depending on the Sigban-type exhaust mechanism section 301, in this simulation, the suction pressure (relative value) of the Sigban-type exhaust mechanism section 301 with the inflow guide section 310 is 78% in No. 1, 74% in No. 2, and 86% in No. 3. Figure 17 It can also be confirmed that, by combining the inflow guide 310 with the front section of the Sigban-type exhaust mechanism 301 (a) compared to (b) not combining it with the inflow guide 310, the pressure in the space of the front section of the Sigban-type exhaust mechanism 301 is significantly reduced. Furthermore, it can be seen that by changing the inner diameter of the inflow guide 310, a change in the degree of suction pressure reduction can be observed.

[0115] Specifically, while a pressure reduction effect can be achieved by combining the inflow guide 310 with the Sigban-type exhaust mechanism 301, the degree of pressure reduction tends to decrease if the inner diameter of the inflow guide 310 is too small or too large. For example, if the inner diameter of the inflow guide 310 is too small, the proportion of the inflow guide 310 overlapping with the rotating disc 320 becomes larger, making it difficult to draw gas fluid from the front space of the Sigban-type exhaust mechanism 301 into the inflow guide 310. Therefore, it is conceivable that the pressure reduction effect brought about by the inflow guide 310 is suppressed. Thus, the inner diameter of the inflow guide 310 is preferably set such that the position of the inner circumferential end 316 of the inflow guide 310 relative to the rotating disc 320 in the radial direction is approximately 10% or more from the base end 321 side of the rotating disc 320. The position of the inner peripheral end 316 of the inflow guide 310 is more preferably about 20% or more from the base end 321 of the rotating circular plate 320, for example, about 30% or more, 40% or more, etc.

[0116] On the other hand, if the inner diameter of the inflow guide 310 is too large, for example, the proportion of the inflow guide 310 overlapping with the rotating circular plate 320 becomes smaller. This means that the gas fluid in the front section of the Sigban-type exhaust mechanism 301 is properly drawn into the inflow guide 310, and the return of the drawn gas fluid from the outer side to the inner side in the radial direction can no longer be adequately suppressed. Therefore, it is conceivable that the suction pressure reduction effect caused by the inflow guide 310 is suppressed. Thus, the inner diameter of the inflow guide 310 is preferably set such that the position of the inner circumferential end 316 of the inflow guide 310 relative to the rotating circular plate 320 in the radial direction is approximately 90% or less from the base end 321 side of the rotating circular plate 320. More preferably, the position of the inner circumferential end 316 of the inflow guide 310 is approximately 80% or less from the base end 321 side of the rotating circular plate 320, for example, approximately 70% or less, 60% or less, etc.

[0117] For example, the inner circumferential end 316 of the inflow guide 310 is preferably positioned in a radial direction orthogonal to the axial direction, ranging from the base end 337 on the rotor shaft side where the first rotating circular plate 320a connects to the rotor shaft 113 to the outer circumferential end 322 of the first rotating circular plate 320a in one or more fixed circular plates 330, within a range of 10% to 90%. More preferably, the inner circumferential end 316 of the inflow guide 310 is positioned between the base end 337 on the rotor shaft side and the outer circumferential end 322 of the first rotating circular plate 320a.

[0118] Furthermore, as described above, even if the reference index is changed to the flow path region, the position of the inner circumferential end 316 of the inflow guide 310 relative to the rotating circular plate 320 will not change significantly. Therefore, the inner diameter of the inflow guide 310 is preferably set such that the position of the inner circumferential end 316 of the inflow guide 310 relative to the flow path region in the radial direction is approximately 10% or more from the base end 321 side of the rotating circular plate 320. More preferably, the position of the inner circumferential end 316 of the inflow guide 310 is approximately 20% or more from the base end 321 side of the rotating circular plate 320 relative to the flow path region, for example, approximately 30% or more, 40% or more, etc. Furthermore, the inner diameter of the inflow guide 310 is preferably set such that the position of the inner circumferential end 316 of the inflow guide 310 relative to the flow path region in the radial direction is approximately 90% or less from the base end 321 side of the rotating circular plate 320. The position of the inner peripheral end 316 of the inflow guide 310 is more preferably about 80% or less from the base end 321 of the rotating circular plate 320 relative to the flow path region, for example, about 70% or less, 60% or less, etc.

[0119] In addition, such as Figure 13As shown, a dimension L for the return flow path is ensured between the fixed circular plate 330 of the Sigban-type exhaust mechanism 301 and the outer surface of the rotating body 103. S3 However, this size L S3 Typically a few millimeters, compared to the radial dimension L of the rotating circular plate 320. R1 The radial dimension L of the flow path region G2 Compared to being sufficiently small (e.g., far less than 10%), the inflow guide section 310 is preferably configured with a guide plate having an inner diameter larger than that of the first fixed circular plate 330a, which is disposed opposite to the downstream side of the first rotating circular plate 320a in one or more fixed circular plates 330. With such a structure, both the back pressure dependence and the exhaust velocity of the Sigban-type exhaust mechanism section 301 can be appropriately improved.

[0120] Furthermore, the width L of the guide plate 311 flowing into the guide section 310 G4 The dimension (in the radial direction) can be preferably the width L of the fixed circular plate 330. S1 It is approximately 10% or more of the radius (dimension in the radial direction). More preferably, it is approximately 20% or more, for example, approximately 30% or more, 40% or more, etc. Furthermore, the width L of the guide circular plate 311 flowing into the guide section 310... G4 The dimension (in the radial direction) can be preferably set as the width L of the fixed circular plate 330. S1 It is less than 90% of the (radial dimension). More preferably, it is less than about 80%, for example, it can be less than about 70%, less than 60%, etc.

[0121] Furthermore, the guide plate 311 of the inflow guide section 310 may also be provided with a spiral groove 314 whose gas flow path length is shorter compared to the fixed plate 330 (first fixed plate 330a). This is because, although in the Sigban-type exhaust mechanism section 301, it is desirable to make the gas flow path as long as possible in order to improve exhaust performance, in the inflow guide section 310, an excessively long inlet gas flow path may make it difficult to draw in gas fluid. With this structure, both back pressure dependence and exhaust velocity can be well balanced and improved.

[0122] Furthermore, the inflow guide section 310 and the first fixed circular plate 330a are not limited to this structure, but for example, Figure 8 and Figure 14As shown, this can be achieved by using the same spiral groove 314 on the opposing surface 311a of the inflow guide 310 and the spiral groove 334 on the first fixed circular plate 330a in the same vortex pattern. This is because the inflow guide 310 has a larger inner diameter than the first fixed circular plate 330a, thus shortening the flow path. If the spiral grooves 314 and 334 of the inflow guide 310 and the first fixed circular plate 330a are made to have the same pattern, the design and manufacture of the inflow guide 310 becomes easier. Furthermore, the "gas flow path length" mentioned here refers to the flow path length of each gas inlet flow path of the inflow guide 310 or the flow path length of each gas flow path of the first fixed circular plate 330a.

[0123] Furthermore, the distance between the valley 313 of the inflow guide 310 and the first rotating circular plate 320a is preferably configured to be larger than the distance between the valley 333 of the first fixed circular plate 330a and the first rotating circular plate 320a. For example, the valley 313 of the inflow guide 310 is preferably configured such that its depth (axial dimension) is larger than that of the valley 333 of the first fixed circular plate 330a. With such a structure, it is easier for the pressure after descending in the inflow guide 310 to affect the space upstream of the inflow guide 310, and the pressure in the front section of the Sigban-type exhaust mechanism section 301 can be appropriately reduced. In addition, it is also preferable that the gas fluid can be easily taken into the inflow guide 310 and that the gas fluid can be more smoothly transported from the inflow guide 310 to the Sigban-type exhaust mechanism section 301. Furthermore, even within an inflow guide section 310 and the first rotating circular plate 320a, the depths of the valleys 313 and 333 may vary depending on their positions. Therefore, the "distance" or "depth" between the valley 313 of the inflow guide section 310 and the first rotating circular plate 320a, as mentioned here, can also refer to the average "distance" or "depth" in the length direction of the gas flow path within the inflow guide section 310 or the first rotating circular plate 320a.

[0124] Furthermore, the outer end of the gas inlet flow path in the radial direction of the inlet guide section 310 can also be positioned corresponding to the outer end of the spiral groove 334 of the first fixed circular plate 330a in the radial direction. With this structure, the gas inlet flow path of the inlet guide section 310 and the gas flow path in the Sigban-type exhaust mechanism section 301 can be made continuous via a shorter return flow path. With this structure, the gas fluid can be delivered to the Sigban-type exhaust mechanism section 301 more smoothly. However, this is not a limitation, but for example... Figure 8 and Figure 14As shown, by using the same vortex-shaped pattern for the spiral groove 314 provided on the opposing surface 311a of the inflow guide 310 and the spiral groove 334 provided on the first fixed circular plate 330a, it is easy to arrange the outer end of the inflow gas flow path of the inflow guide 310 in the radial direction and the outer end of the spiral groove 334 of the first fixed circular plate 330a in the radial direction in opposing positions. Furthermore, even when the vortex-shaped pattern is the same in top view, the depth of the gas flow path can be set differently.

[0125] In the above embodiment, the inflow guide 310 is configured to exert a molecular drag effect between itself and the first rotating circular plate 320a. However, the inflow guide 310 does not necessarily have to exert a molecular drag effect between itself and the first rotating circular plate 320a. For example, the inflow guide 310 can be configured such that the gas flow introduced into the inflow guide 310 by the exhaust force brought by the Sigman-type exhaust mechanism 301 in the rear section is suppressed from returning from the outer side to the inner side in the radial direction. With such a structure, the inflow guide 310 can also reduce the pressure in the space in front of the Sigman-type exhaust mechanism 301, which helps to increase the exhaust velocity.

[0126] In the above embodiment, the hill 312 of the inflow guide 310 is provided, for example, in the region opposite to the first rotating circular plate 320a, and is not provided in the return flow path. Specifically, in Figure 13 In this configuration, a predetermined gap L is provided between the mountain section 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 mountain section 312 of the inflow guide section 310 may also have a shape that is continuously connected to the mountain section 332 of the first fixed circular plate 330a disposed on the downstream side.

[0127] Figure 18 This is an example of a partial cross-sectional view of the inflow guide 310A in another embodiment. For example, the hill 312A of the inflow guide 310A extends radially to the inner circumferential surface of the fixed spacer 315, and extends axially to the lower end throughout the inner circumferential surface of the fixed spacer 315. In this case, although not specifically illustrated, the hill 332 of the first fixed circular plate 330a is disposed on the inner side of the downwardly extending portion of the hill 312A of the inflow guide 310 in the radial direction. As a result, the molecular dragging effect in the return flow path can be suppressed. Furthermore, the gas flow path of the inflow guide 310 and the gas flow path in the Sigban-type exhaust mechanism 301 can be made more reliably continuous, and the gas fluid can be delivered to the Sigban-type exhaust mechanism 301 more smoothly.

[0128] Furthermore, the inflow guide portion in the above embodiment can circulate independently as a reconfigurable part of the vacuum pump. From this perspective, the present invention provides an inflow guide portion for a vacuum pump that guides the inflow of gas. Here, the vacuum pump refers to a so-called Sigban-type vacuum pump, which includes: one or more rotating discs; and one or more fixed discs, axially opposed to each of the one or more rotating discs, with spiral grooves having valleys and ridges on their opposing surfaces; the introduced gas is discharged by the interaction of the one or more rotating discs and the one or more fixed discs. Moreover, the inflow guide portion of the present invention includes: a guide disc; and a ridge protruding from the guide disc toward the first rotating disc, which is closer to the suction port side of the vacuum pump than the one or more rotating discs. By arranging this inflow guide portion immediately upstream of the rotating disc closest to the suction port of the Sigban-type vacuum pump, both the back pressure dependence and the exhaust velocity of such a vacuum pump can be appropriately improved.

[0129] Furthermore, the present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above have been explained in detail to facilitate understanding of the present invention, and are not necessarily limited to having all the described structures. Moreover, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, and it is also possible to add and combine structures of other embodiments to the structure of one embodiment. Furthermore, with respect to a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0130] In addition, the above-described embodiments at least disclose the structures described in the claims.

[0131] Explanation of reference numerals in the attached figures 100, 100A, 300… Turbomolecular pump; 101… Inlet; 102… Rotating blade; 102d… Cylindrical section (rotating cylinder); 103… Rotating body; 113… Rotor shaft; 123… Fixed blade; 125… Fixed blade spacer; 127… Outer cylinder (shell); 129… Base section (shell); 133… Exhaust port; 201… Turbomolecular pump mechanism; 301… Siegban type exhaust mechanism; 310, 310A… Inflow guide section; 311… Guide plate; 3 11a…opposing surface; 312, 312A…mountain; 313…valley; 314…spiral groove; 315…fixed spacer; 316…inner circumferential end; 317…base end; 320…rotating circular plate; 320a…first rotating circular plate; 321…base end; 322…outer circumferential end; 330…fixed circular plate; 330a…first fixed circular plate; 331…circular plate portion; 332…mountain; 333…valley; 334…spiral groove; 335…fixed spacer; 337…base end.

Claims

1. A vacuum pump, comprising: The casing has an air intake port; The rotor shaft is housed within the aforementioned housing; One or more rotating circular plates, capable of rotating together with the aforementioned rotor shaft; and One or more fixed circular plates are axially opposed to each of the aforementioned one or more rotating circular plates, and spiral grooves with valleys and peaks are provided on the opposing surfaces; A gas flow path is formed by means of the aforementioned spiral grooves that are opposite to one or more of the aforementioned rotating circular plates; By means of the interaction between the aforementioned one or more rotating circular plates and the aforementioned one or more fixed circular plates, the gas introduced from the aforementioned intake port is discharged; Its features are, The first rotating disc, which is closer to the air intake side than the aforementioned one or more rotating discs, has an inflow guide section that guides the inflow of the aforementioned gas.

2. The vacuum pump as described in claim 1, characterized in that, The aforementioned inflow guide section includes a guide circular plate, which has an inner diameter larger than that of the first fixed circular plate, which is disposed opposite to the downstream side of the aforementioned first rotating circular plate.

3. The vacuum pump as described in claim 2, characterized in that, The aforementioned guide plate has a spiral groove on its opposing surface, which is opposite to the aforementioned first rotating plate and has a valley and a mountain, and the gas flow path length is shorter than that of the aforementioned first fixed plate.

4. The vacuum pump as described in claim 2, characterized in that, The aforementioned inflow guide has a spiral groove with a valley and a mountain on its opposing surface opposite to the aforementioned first rotating circular plate; The aforementioned mountain portion of the inflow guide has a shape that is continuously connected to the mountain portion of the aforementioned first fixed circular plate disposed on the downstream side.

5. The vacuum pump as described in claim 1, characterized in that, The aforementioned inflow guide section includes a guide circular plate and a mountain-shaped portion protruding from the aforementioned guide circular plate toward the aforementioned first rotating circular plate; The aforementioned mountain and the aforementioned guide plate of the aforementioned inflow guide section are constructed to guide the aforementioned gas from the inside to the outside in a radial direction orthogonal to the aforementioned axial direction when the aforementioned one or more rotating plates are rotated; The outer end of the aforementioned gas inlet flow path in the aforementioned radial direction is positioned at a position corresponding to the outer end of the aforementioned spiral groove in the aforementioned radial direction of the first fixed circular plate, which is disposed opposite to the downstream side of the aforementioned first rotating circular plate in one or more of the aforementioned fixed circular plates.

6. The vacuum pump as claimed in claim 1, characterized in that, In a radial direction orthogonal to the aforementioned axial direction, the inner end of the aforementioned inflow guide is located in the range of 10% to 90% from the rotor shaft base end where the aforementioned first rotating circular plate is connected to the aforementioned rotor shaft to the outer end of the aforementioned first rotating circular plate in one or more of the aforementioned fixed circular plates.

7. The vacuum pump as described in claim 6, characterized in that, In a radial direction orthogonal to the aforementioned axial direction, the inner end of the aforementioned inflow guide is positioned between 40% and 60% of the distance from the base end of the aforementioned rotor shaft to the outer end of the aforementioned first rotating circular plate.

8. The vacuum pump as claimed in claim 1, characterized in that, The aforementioned inflow guide is configured to exert a molecular dragging effect on the aforementioned gas between itself and the aforementioned first rotating plate when the aforementioned one or more rotating plates are rotating.

9. The vacuum pump as claimed in claim 1, characterized in that, The aforementioned inflow guide has a spiral groove with a valley and a mountain on its opposing surface opposite to the aforementioned first rotating circular plate; The distance between the valley portion of the aforementioned inflow guide portion and the aforementioned first rotating circular plate is configured to be greater than the distance between the valley portion of the aforementioned first fixed circular plate, which is disposed opposite to the downstream side of the aforementioned first rotating circular plate, and the aforementioned first rotating circular plate.

10. An inflow guiding component for a vacuum pump, for guiding the inflow of gas, said vacuum pump comprising: One or more rotating circular plates; and One or more fixed circular plates are axially opposed to each of the aforementioned one or more rotating circular plates, and spiral grooves with valleys and peaks are provided on the opposing surfaces; The introduced gas is discharged by means of the interaction between the aforementioned one or more rotating circular plates and the aforementioned one or more fixed circular plates; The aforementioned inflow guide component is characterized by, The aforementioned inflow guide components include: Guide circular plate; and The mountain section protrudes from the guide plate toward the first rotating plate, which is closer to the suction port side of the vacuum pump than the aforementioned one or more rotating plates.

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