Vacuum pump

Abstract

The present application provides a vacuum pump with excellent exhaust performance. The vacuum pump is provided with a Seeburg type exhaust mechanism portion (201) provided with a Seeburg spiral groove portion (262) on at least one of a rotating circular plate (220a-220c) and a fixed circular plate (219a, 219b), a Holweck type exhaust mechanism portion (301) provided with a threaded groove (131a) on at least one of a cylindrical portion (102d) of a rotating body (103) and a threaded spacer (131), the Holweck type exhaust mechanism portion (301) being arranged on a downstream side of the Seeburg type exhaust mechanism portion (201), and the vacuum pump is characterized in that a flow path depth of the Holweck type exhaust mechanism portion (301) is continuously constant at a predetermined depth (H2), and the Seeburg type exhaust mechanism portion (201) has an area continuously constant at the predetermined depth (H2) from a predetermined position.

Description

Technical Field

[0001] This invention relates, for example, to vacuum pumps such as turbomolecular pumps. Background Technology

[0002] Generally, turbomolecular pumps are known as a type of vacuum pump. In this turbomolecular pump, a rotating blade is rotated by energizing a motor inside the pump body, which deflects gas molecules (process gas) drawn into the pump body, thereby expelling the gas.

[0003] Furthermore, among such turbomolecular pumps, there are Sigbarn-type pumps (Patent Documents 1-3). In this Sigbarn-type molecular pump, multiple vortex-shaped flow paths spaced apart by hill-shaped sections are formed in the gap between the rotating and fixed circular plates. Moreover, the Sigbarn-type molecular pump applies tangential momentum to the gas molecules diffusing into the vortex-shaped flow paths by means of the rotating circular plate, and applies a dominant directionality in the exhaust direction by means of the vortex-shaped flow paths to exhaust gas.

[0004] Furthermore, there are also threaded groove type turbomolecular pumps (Patent Document 4), etc. In this threaded groove type turbomolecular pump, the threaded groove spacer (70) and the rotor cylindrical part (10) face each other with a predetermined gap, and the threaded groove is the flow path for conveying gas.

[0005] Patent Document 1: Japanese Patent No. 6228839.

[0006] Patent Document 2: Japanese Patent No. 6353195.

[0007] Patent document 3: Japanese Patent No. 6616560.

[0008] Patent document 4: Japanese Patent Application Publication No. 2013-217226.

[0009] However, in the aforementioned various turbomolecular pumps and similar vacuum pumps, improved exhaust performance is achieved through a variety of designs. Furthermore, the main indicators of this exhaust performance include "exhaust velocity," "compression performance," and "back pressure characteristics." Among these, "exhaust velocity" simply indicates the flow rate of gas that can be discharged per unit time. Conversely, "compression performance" is an indicator of how much gas can be compressed, and it depends on whether the discharged gas is a compressible fluid.

[0010] Furthermore, "back pressure characteristics" are an indicator of the influence of an auxiliary pump (booster pump) located downstream of the turbomolecular pump in a vacuum exhaust system. Based on these "back pressure characteristics," the limiting back pressure that can maintain exhaust performance is determined.

[0011] Furthermore, according to the inventors' findings, regarding the "back pressure characteristics," the limiting back pressure that can maintain exhaust performance is also related to the gas flow path volume (gas flow path capacity), but is mainly affected by the flow path length. Therefore, the inventors concluded that extending the flow path length of the exhaust gas is useful when it is desired to improve the "back pressure characteristics." Summary of the Invention

[0012] The purpose of this invention is to provide a vacuum pump with excellent exhaust performance.

[0013] (1) In order to achieve the above objective, the present invention is a vacuum pump comprising a Sigbarn exhaust mechanism having a vortex-shaped groove provided on at least one of a rotating circular plate and a fixed circular plate, and a Hallwick exhaust mechanism having a spiral-shaped groove provided on at least one of a rotating cylinder and a fixed cylinder, wherein the Hallwick exhaust mechanism is disposed downstream of the Sigbarn exhaust mechanism, and the vacuum pump is characterized in that the flow path depth of the Hallwick exhaust mechanism is continuously constant at a predetermined depth, and the Sigbarn exhaust mechanism has a region that is continuously constant at the predetermined depth from a predetermined position.

[0014] (2) In addition, in order to achieve the above objectives, other aspects of the present invention in the vacuum pump described in (1) are characterized in that they have multiple layers of the aforementioned Sigbarn exhaust mechanisms, and the flow path depth of at least the lowest layer of the aforementioned Sigbarn exhaust mechanisms connected to the aforementioned Holwick exhaust mechanism is continuously constant at the aforementioned predetermined depth.

[0015] (3) In addition, in order to achieve the above objectives, other versions of the present invention in the vacuum pump described in (1) or (2) are characterized in that a rotating wing and a fixed wing are provided on the upstream side of the aforementioned Sigbarn exhaust mechanism, the aforementioned rotating wing having a wing row, and the aforementioned fixed wing being configured to be spaced apart from the aforementioned rotating wing in the axial direction by a predetermined interval.

[0016] Invention Effects

[0017] According to the above invention, a vacuum pump with excellent exhaust performance can be provided. Attached Figure Description

[0018] Figure 1 This is an explanatory diagram schematically illustrating the structure of a turbomolecular pump according to one embodiment of the present invention.

[0019] Figure 2 This is the circuit diagram of the amplification circuit.

[0020] Figure 3 This is a timing diagram representing the control when the current command value is greater than the detected value.

[0021] Figure 4 This is a timing diagram representing the control when the current command value is smaller than the detected value.

[0022] Figure 5 It means Figure 1 The diagram illustrates the specific structure of the main components of a turbomolecular pump and a general diagram of gas flow.

[0023] Figure 6 (a) is to be Figure 5 (a) is a longitudinal sectional view enlarged by a double-dotted line frame L, and (b) is an explanatory diagram that schematically shows the upstream side of the fixed circular plate on the downstream side.

[0024] Figure 7 It is a schematic representation Figure 5 A diagram illustrating the flow of gas within the area enclosed by the double-dotted line L.

[0025] Figure 8 (a) is a graph showing the back pressure characteristics when gas A, as a gas, flows in a turbomolecular pump according to an embodiment of the present invention, and (b) is a graph showing the back pressure characteristics when gas B, as another type of gas, flows.

[0026] Figure 9 This is a graph showing the relationship between the inlet depth and gas pressure of the experimental model of the Holwick exhaust flow path.

[0027] Figure 10 This is an explanatory diagram that uses a model to represent the exhaust mechanism of the slot.

[0028] Figure 11 (a) is a general representation Figure 10 A graph showing the relationship between the flow path location and flow path depth in the model, (b) is similarly represented. Figure 10 A graph showing the relationship between flow path location and pressure in the model.

[0029] Figure 12 (a) is an illustration of a general model of the Cueter-Poiseuille flow between parallel plates, and (b) is a diagram showing the region where the counterflow occurs.

[0030] Figure 13 (a) is a graph showing the back pressure characteristics of a certain gas in a previous structure, and (b) is a graph showing the back pressure characteristics of other types of gases in a previous structure. Detailed Implementation

[0031] Hereinafter, a vacuum pump according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This refers to a turbomolecular pump 100, which is a vacuum pump according to an embodiment of the present invention. This turbomolecular pump 100 is connected, for example, to the vacuum chamber (not shown) of an object device such as a semiconductor manufacturing apparatus.

[0032] Figure 1 The image shows a longitudinal sectional view of the turbomolecular pump 100. Additionally, Figure 1 To avoid unnecessary complexity in the accompanying drawings, the internal structure of the turbomolecular pump 100 is schematically shown. In particular, the turbomolecular pump 100 of this embodiment has more key feature structures in the slotted exhaust mechanism section of the exhaust mechanism. Therefore, Figure 1 The simplified diagram of the exhaust mechanism illustrates the basic structure of the turbomolecular pump 100 from intake to exhaust. Furthermore, Figure 5 The specific structure and operation of the slot exhaust mechanism will be described later. A detailed description of the slot exhaust mechanism will follow the overall description of the turbomolecular pump 100.

[0033] Figure 1 In this design, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Furthermore, inside the outer cylinder 127, a rotating body 103 is provided, which has multiple rotating blades 102 (102a, 102b, 102c...) radially and in multiple layers around its periphery for drawing and discharging gas. A rotor shaft 113 is mounted at the center of this rotating body 103, and this rotor shaft 113 is suspended in the air and its position is controlled, for example, by a 5-axis controlled magnetic bearing.

[0034] The upper radial electromagnets 104 consist of four electromagnets arranged in pairs along the X and Y axes. Near each upper radial electromagnet 104, and corresponding to it, are four upper radial sensors 107. These sensors 107 may be, for example, inductive sensors with conductive windings or eddy current sensors, and detect the position of the rotor shaft 113 based on changes in the inductance of the conductive windings that correspond 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 to the rotor shaft 113, and transmit this information to the control device 200.

[0035] In this control device 200, for example, a compensation loop 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 amplification circuit 150 shown (described later) performs excitation control on the upper radial electromagnet 104 based on the excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

[0036] Furthermore, the rotor shaft 113 is formed of a material with high magnetic permeability (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.

[0037] Furthermore, the axial electromagnets 106A and 106B are configured as a circular metal disc 111 located at the lower part of the rotor shaft 113, sandwiched between the upper and lower parts. The metal disc 111 is made of a highly magnetically permeable 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.

[0038] 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 amplification 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.

[0039] 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 without contact. Furthermore, the amplification 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.

[0040] 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, causing the rotor shaft 113 to be rotated via an electromagnetic force acting between it and the rotor shaft 113. Furthermore, a rotational speed sensor, such as a Hall element, analyzer, encoder, etc. (not shown in the figure), is installed in the motor 121, and the rotational speed of the rotor shaft 113 is detected by means of the detection signal of the rotational speed sensor.

[0041] Furthermore, for example, a phase sensor (not shown) is installed 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 rotation speed sensor are used together to detect the position of the magnetic poles.

[0042] Multiple fixed blades 123 (123a, 123b, 123c, etc.) are arranged with a small gap (a predetermined interval) between them and the rotating blades 102 (102a, 102b, 102c, etc.). The rotating blades 102 (102a, 102b, 102c, etc.) are tilted 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.

[0043] Furthermore, the fixed wing 123 is also formed to be inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and is alternately arranged with the rotating wing 102 on the inner side of the outer cylinder 127. Moreover, the outer peripheral end of the fixed wing 123 is supported in a state of being inserted between a plurality of stacked fixed wing spacers 125 (125a, 125b, 125c...).

[0044] The fixed wing 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 wing spacer 125 with slight gaps. 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 and communicates with the outside. Exhaust gas entering the intake port 101 from the cavity (vacuum chamber) side and being transferred to the base portion 129 is directed to the exhaust port 133.

[0045] Furthermore, depending on the application of the turbomolecular pump 100, a threaded spacer 131 is provided between the lower part of the fixed wing spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical component made of a metal such as aluminum, copper, stainless steel, iron, or an alloy composed of these metals, and has multiple helical threaded grooves 131a engraved on its inner circumferential surface. The direction of the helix of the threaded grooves 131a is the direction in which the molecules of the exhaust gas are moved toward the exhaust port 133 when they move in the rotational direction of the rotating body 103. At the lowest part, the cylindrical part 102d hangs down, which is continuous with the rotating wing 102 (102a, 102b, 102c...) of the rotating body 103 (more specifically, continuous with the rotating circular plates 220a to 220c of the Sigbarn-type exhaust mechanism part 201 described later). The outer circumferential surface of the cylindrical portion 102d is cylindrical and extends into 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 transferred to the threaded groove 131a by the rotating blade 102 and the fixed blade 123, is guided by the threaded groove 131a and sent to the base portion 129.

[0046] 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, and stainless steel. The base portion 129 physically holds the turbomolecular pump 100 and also functions as a heat conduction path, so it is desirable to use metals such as iron, aluminum, and copper that have rigidity and high thermal conductivity.

[0047] In this structure, when the rotating blade 102 and the rotor shaft 113 are driven to rotate by the motor 121, the exhaust gas is drawn from the cavity through the intake port 101 by the action of the rotating blade 102 and the fixed blade 123. The exhaust gas drawn from the intake port 101 passes between the rotating blade 102 and the fixed blade 123 and is transferred to the base portion 129. At this time, due to the frictional heat generated when the exhaust gas comes into contact with the rotating blade 102, the conduction of heat generated by the motor 121, etc., the temperature of the rotating blade 102 rises, but this heat is transferred to the fixed blade 123 side through radiation or conduction by the gas molecules of the exhaust gas.

[0048] The fixed wing spacers 125 are joined together on the outer periphery to transfer heat received by the fixed wing 123 from the rotating wing 102, frictional heat generated when the exhaust gas comes into contact with the fixed wing 123, and so on, to the outside.

[0049] Furthermore, the above description indicates that the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotating body 103, and a threaded groove 131a is 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.

[0050] Furthermore, depending on the application of the turbomolecular pump 100, there are also cases where the electrical assembly is surrounded by the stator column 122, so that the gas drawn from the intake port 101 does not enter the electrical assembly consisting 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 stator column 122 is kept at a fixed pressure by means of flushing gas.

[0051] In this case, a pipe (not shown) is installed at the base portion 129, through which flushing gas is introduced. The introduced flushing gas passes 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, and is sent to the exhaust port 133.

[0052] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that are individually adjusted according to the model type. 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 these components, and a substrate 143 for mounting them. This electronic circuit section 141 is housed below a rotational speed sensor (not shown) near, for example, the center of a base section 129, and is closed by an airtight bottom cover 145. The aforementioned base section 129 constitutes the lower part of the turbomolecular pump 100.

[0053] However, in the semiconductor manufacturing process, the process gas introduced into the cavity contains substances that solidify when 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. During the process gas's journey from the intake port 101 to the exhaust port 133, if its pressure becomes higher than a predetermined value or its temperature becomes lower than a predetermined value, the process gas solidifies and accumulates inside the turbomolecular pump 100.

[0054] For example, when using SiCl4 as the process gas in an Al etching apparatus, the vapor pressure curve shows that a low vacuum (760 [torr] ~ 10) is suitable. -2 At low temperatures (approximately 20°C), solid products (e.g., AlCl3) precipitate and accumulate inside the turbomolecular pump 100. As a result, the accumulation of process gas precipitates inside the turbomolecular pump 100 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.

[0055] Therefore, in order to solve this problem, conventionally, a heater (not shown in the figure) and an annular water-cooling pipe 149 (not shown in the figure) are wound around the outer periphery of the base portion 129, and a temperature sensor (e.g., a thermistor, not shown in the figure) is embedded in the base portion 129, so that the heating of the heater and the cooling of the water-cooling pipe 149 are controlled by maintaining the temperature of the base portion 129 at a constant high temperature (set temperature) based on the signal of the temperature sensor (hereinafter referred to as TMS; TMS; Temperature Management System).

[0056] Next, regarding the turbomolecular pump 100 configured in this way, the amplification circuit 150 for excitation control 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 the amplification circuit 150.

[0057] 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. 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 field-effect transistors, having a diode structure with its source-drain connection.

[0058] At this time, transistor 161 has its diode's cathode terminal 161a connected to the positive terminal 171a, and its anode terminal 161b connected to one end of the electromagnet winding 151. Furthermore, transistor 162 has its diode's cathode terminal 162a connected to the current detection circuit 181, and its anode terminal 162b connected to the negative terminal 171b.

[0059] On the other hand, the diode 165 for current regeneration has its cathode terminal 165a connected to one end of the electromagnet winding 151, and its anode terminal 165b connected to the negative terminal 171b. Similarly, the diode 166 for current regeneration has its cathode terminal 166a connected to the positive terminal 171a, and its anode terminal 166b connected to the other end of the electromagnet winding 151 via a current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall effect current sensor and a resistive element.

[0060] The amplification circuit 150 constructed as described above corresponds to one electromagnet. Therefore, with 5-axis control of the magnetic bearing and a total of 10 electromagnets 104, 105, 106A, and 106B, the same amplification circuit 150 is constructed for each electromagnet, and the 10 amplification circuits 150 are connected in parallel with respect to the power supply 171.

[0061] Furthermore, the amplification control circuit 191 is, for example, composed of a digital signal processor (hereinafter referred to as DSP unit) of the control device 200 (not shown in the figure), which switches the transistors 161 and 162 on / off.

[0062] The amplification 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. Based on the comparison result, it determines the magnitude of the pulse width (pulse width times Tp1 and Tp2) generated within one cycle of PWM control, i.e., the control cycle Ts. As a result, gate drive signals 191a and 191b with this pulse width are output from the amplification control circuit 191 to the gate terminals of transistors 161 and 162.

[0063] Furthermore, high-speed and powerful position control of the rotating body 103 is required when it accelerates through a resonance point or when external disturbances occur during constant-speed operation. Therefore, in order to enable a rapid increase (or decrease) in the current flowing to the electromagnet winding 151, a high voltage of approximately 50V is used as the power supply 171. In addition, to stabilize the power supply 171, a capacitor is typically connected between the positive terminal 171a and the negative terminal 171b of the power supply 171 (illustration omitted).

[0064] In this structure, when transistors 161 and 162 are turned on, the current flowing to the electromagnet winding 151 (hereinafter referred to as electromagnet current iL) increases, and when they are turned off, the electromagnet current iL decreases.

[0065] Furthermore, when one of transistors 161 and 162 is turned on while the other is turned off, the so-called flywheel current is maintained. This flywheel current flows in the amplification circuit 150, thereby reducing the hysteresis loss of the amplification circuit 150 and suppressing the overall power consumption of the circuit to a lower level. Moreover, by controlling transistors 161 and 162 in this way, high-frequency noise such as high-modulation waves generated at the turbomolecular pump 100 can be reduced. Furthermore, by measuring this flywheel current using the current detection circuit 181, the electromagnet current iL flowing in the electromagnet winding 151 can be detected.

[0066] That is, if the detected current value is smaller than the current command value, such as Figure 3 As shown, transistors 161 and 162 are switched on once during the control period Ts (e.g., 100 μs) for a duration equivalent to the pulse width time Tp1. Therefore, during this period, the electromagnet current iL increases from the positive terminal 171a to the negative terminal 171b, increasing to the current value iLmax (not shown) that can flow through transistors 161 and 162.

[0067] On the other hand, if the detected current value is larger than the current command value, such as Figure 4 As shown, transistors 161 and 162 are switched off once during the control cycle Ts for a period of time equivalent to the pulse width time Tp2. Therefore, during this period, the electromagnet current iL decreases from the negative terminal 171b toward the positive terminal 171a to the current value iLmin (not shown) that can be regenerated through diodes 165 and 166.

[0068] Furthermore, in either case, after pulse width times Tp1 and Tp2, one of transistors 161 and 162 is turned on. Therefore, during this period, the flywheel current at amplifier circuit 150 is maintained.

[0069] The turbomolecular pump 100 with such a basic structure Figure 1 The upper side (intake port 101 side) is the intake section connected to the target equipment side, and the lower side (provided on one side of the base 129 with exhaust port 133 protruding to the left in the figure) is the exhaust section connected to an auxiliary pump (a booster pump for rough pumping), etc., which is not shown in the figure. Furthermore, the turbomolecular pump 100, in addition to... Figure 1 In addition to the vertical position shown, it can also be used in inverted, horizontal, and tilted positions.

[0070] Furthermore, in the turbomolecular pump 100, the aforementioned outer cylinder 127 and base portion 129 are combined to form a shell (hereinafter referred to as the combination of the two as a "main body cover" etc.). In addition, the turbomolecular pump 100 is electrically (and structurally) connected to a box-shaped electrical housing (not shown), and the aforementioned control device 200 is housed in the electrical housing.

[0071] The internal structure of the main body cover (combination of outer cylinder 127 and base 129) of turbomolecular pump 100 can be divided into a rotating mechanism section that rotates rotor shaft 113 and the like by means of motor 121, and an exhaust mechanism section that is driven by the rotating mechanism section. In addition, the exhaust mechanism section can be considered as a turbomolecular pump mechanism section composed of rotating blade 102, fixed blade 123 and the like, or a slot exhaust mechanism section composed of cylindrical section 102d, threaded spacer 131 and the like (described later).

[0072] In addition, the aforementioned flushing gas (protective gas) is used to protect the bearing parts, the rotor 102, etc., to prevent corrosion caused by the exhaust gas (process gas), and to cool the rotor 102.

[0073] The flushing gas can be supplied using conventional methods.

[0074] For example, although the illustration is omitted, a flushing gas flow path extending linearly in the radial direction is provided at a predetermined location on the base portion 129 (a position approximately 180 degrees away from the exhaust port 133, etc.). Furthermore, flushing gas is supplied from the outside of the base portion 129 via a flushing gas cylinder (N2 gas cylinder, etc.), a flow regulator (valve device), etc., relative to this flushing gas flow path (more specifically, a flushing port that serves as the gas inlet).

[0075] The aforementioned protective bearing 120 is also called a "bottom-out (T / D) bearing" or "support bearing". With the help of these protective bearings 120, even in the event of problems such as electrical system troubles or atmospheric intrusion, the position and orientation of the rotor shaft 113 will not change significantly, and the rotor blade 102 and its surrounding parts will not be damaged.

[0076] In addition, the figures showing the structure of the turbomolecular pump 100 are as follows ( Figure 1 , Figure 5 In the figures (etc.), the description of the cross-sectional lines representing the parts is omitted to avoid making the drawings complicated.

[0077] Next, regarding the aforementioned exhaust mechanism, based on Figure 5 The accompanying diagrams will provide further explanation. Additionally, Figure 5 Indicates and Figure 1 The pump schematically shown is the same as the turbomolecular pump 100, but as mentioned earlier, in order to illustrate the specific structure and operation of the exhaust mechanism, it is similar to... Figure 1 The difference specifically refers to the exhaust mechanism section (composed of the Sigbarn-type exhaust mechanism section 201 and the Holwick-type exhaust mechanism section 301) and its surrounding parts.

[0078] The slot exhaust mechanism of this embodiment is as follows: Figure 5 and Figure 6 As shown in (a), the device includes a Sigbarn-type exhaust mechanism section 201 and a Holwick-type exhaust mechanism section 301. The Sigbarn-type exhaust mechanism section 201 is spatially continuous with respect to the next stage (immediate downstream side) of the turbomolecular pump mechanism section composed of the aforementioned rotating blades 102 (102a, 102b, 102c... each having a wing row), fixed blades 123 (123a, 123b, 123c...), etc. On the other hand, the Holwick-type exhaust mechanism section 301 is spatially continuous with respect to the next stage (immediate downstream side) of the Sigbarn-type exhaust mechanism section 201.

[0079] Furthermore, the Sigbarn-type exhaust mechanism 201 is configured to move gas radially with reference to the axis of the rotor shaft 113. In contrast, the Holwick-type exhaust mechanism 301 is configured to move gas primarily in the axial direction of the rotor shaft 113.

[0080] Here, the Hallwick-type exhaust mechanism 301 of this embodiment performs radial gas transfer with reference to the axis of the rotor shaft 113 and axial gas transfer in the direction of the rotor shaft 113. However, it can also be classified as the Sigbarn-type exhaust mechanism 201, which includes a portion that performs radial gas transfer, and the portion that only performs gas transfer in the direction of the rotor shaft 113 is classified as the Hallwick-type exhaust mechanism 301. Details regarding the Hallwick-type exhaust mechanism 301 of this embodiment will be described later.

[0081] The aforementioned Sigbarn-type exhaust mechanism 201 is a Sigbarn-type exhaust mechanism, having fixed circular plates 219a and 219b and rotating circular plates 220a to 220c. The rotating circular plates 220a to 220c and the fixed circular plates 219a and 219b are made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components.

[0082] Fixed circular plates 219a and 219b are integrally assembled into the main body cover (the combination of outer cylinder 127 and base portion 129). Furthermore, one layer of fixed circular plates (219a and 219b) is inserted between two layers of rotating circular plates (220a to 220c) arranged axially on the rotor shaft 113.

[0083] The rotating circular plates 220a to 220c are integrally formed with the cylindrical rotating body 103, and rotate in the same direction as the rotating body 103 rotates. That is, the rotating circular plates 220a to 220c also rotate integrally with the rotating blades 102 (102a, 102b, 102c...).

[0084] In this embodiment, the number of fixed circular plates 219a and 219b in the Sigbarn-type exhaust mechanism 201 is two, and the number of rotating circular plates 220a to 220c is three. Furthermore, the fixed circular plates 219a and 219b and the rotating circular plates 220a to 220c are arranged alternately along the axial direction of the rotor shaft 113 from the intake side (intake port 101 side) in the order of rotating circular plate 220a, fixed circular plate 219a, rotating circular plate 220b, fixed circular plate 219b, and rotating circular plate 220c.

[0085] Furthermore, between the fixed circular plates 219a and 219b and the rotating circular plates 220a to 220c, such as Figure 6 As shown in magnification in (a), multiple protruding hills 261 with rectangular cross-sectional shapes are formed. Furthermore, vortex-shaped flow paths, namely Sigbarn vortex-shaped grooves 262, are formed between adjacent hills 261.

[0086] Additionally, the following, in Figure 5 , Figure 6 In (a), the intake side (intake port 101 side) shown at the top of the figure is called the "upstream side", and the exhaust side (exhaust port 133 side) shown at the bottom of the figure is called the "downstream side".

[0087] also, Figure 6 (a) will Figure 5 The slot exhaust mechanism, located on the right side of the rotor shaft 113 (within the double-dotted box L), is shown in enlarged view. Furthermore, the slot exhaust mechanism is symmetrical about the axis of the main body cover (the combination of the outer cylinder 127 and the base 129), the rotor shaft 113, etc. Figure 5 The structure is symmetrical (both sides are symmetrical), so only the following will be discussed here. Figure 5 The right side of the image is shown in enlarged form, while the left side is omitted from the image.

[0088] like Figure 6As shown in (a), at each of the fixed circular plates 219a and 219b, the aforementioned mountain portion 261 is integrally formed with the two plate surfaces 266 and 267. Hereinafter, the reference numerals for each of the fixed circular plates 219a and 219b and the plate surfaces 266 and 267 are common, and the common reference numerals (here, reference numerals 266 and 267) will be used to explain the different fixed circular plates 219a and 219b.

[0089] Furthermore, regarding the mountain section 261, regardless of the differences between the fixed circular plates 219a and 219b, and consequently also regardless of the differences between the plate surfaces 266 and 267, the reference numeral 261 common to all mountain sections will be used for explanation. Furthermore, Figure 6 In (a), to prevent the drawings from becoming complicated, the reference numerals are mainly used for the upstream fixed circular plate 219a of the fixed circular plates 219a and 219b, while the reference numerals for the downstream fixed circular plate 219b are omitted.

[0090] Fixed circular plates 219a and 219b have a through hole 270 formed in the center. Figure 6 (b) also indicates the circular plate-shaped main body 268. Figure 6 At the fixed circular plate 219a on the upstream side, as shown above in (a), the plate surface 266 on the upstream side is inclined in such a way that it gets closer to the plate surface 267 on the downstream side as it moves from the central side (through hole 270 side) of the main body 268 toward the outer periphery side, which is the base end side.

[0091] In contrast, the downstream plate surface 267 is formed to be approximately horizontal in the figure. In other words, the downstream plate surface 267 of the upstream fixed circular plate 219a is formed to be approximately perpendicular to the axis of the rotor shaft 113. Furthermore, the thickness of the main body portion 268 of the upstream fixed circular plate 219a is not constant, and gradually thins from the inner circumference side, which is the central side, to the outer circumference side, which is the base end side.

[0092] On the other hand, at the fixed circular plate 219b on the downstream side, the main body 268 is formed with a substantially uniform thickness from the central side to the outer peripheral side, which serves as the base end side.

[0093] Here, "outer periphery" refers to the outer side of the main body 268 of the fixed circular plates 219a and 219b in the normal direction (radial direction), and "inner periphery" also refers to the inner side of the main body 268 in the normal direction (radial direction).

[0094] The outer periphery of the main body 268 of the fixed circular plates 219a and 219b is machined to have a generally uniform and equal wall thickness, and is supported in a state of being inserted between multiple stacked fixed circular plate spacers 269.

[0095] In addition, on each of the surfaces 266 and 267 of each of the fixed circular plates 219a and 219b, besides Figure 5 and Figure 6 In addition to (a), such as Figure 6 (b) schematically shows that the aforementioned plurality of hill-shaped sections 261 are provided. The hill-shaped sections 261 are formed in a spiral shape centered on the center of the main body 268 on the plate surfaces 266 and 267 of the main body 268. Furthermore, the hill-shaped sections 261 extend from the periphery (inner periphery) of the through hole 270 to the outer periphery (located near the front of the fixed circular plate spacer 269) while depicting a smooth curve.

[0096] here, Figure 6 (b) is shown as an example, schematically illustrating the state of the fixed circular plate 219b on the downstream side as viewed axially from the upstream side of the plate surface 266. Furthermore, in Figure 6 In (b), the mountain 261 formed on the upstream side of the plate surface 266 is represented by a solid line, while the mountain 261 formed on the downstream side of the plate surface 267 is represented by a relatively thin dashed line. Furthermore, in Figure 6 In (b), the illustration of the fixed circular plate spacer 269 is omitted. Furthermore, in Figure 6 In (b), the rotating body 103 and the rotor shaft 113 are represented by imaginary lines (double-dotted lines).

[0097] At each of the fixed circular plates 219a and 219b, a mountain-shaped portion 261 protrudes from each of the plate surfaces 266 and 267 of the circular plate-shaped main body 268 at a defined predetermined angle. In this embodiment, as described above, the upstream plate surface 266 of the upstream fixed circular plate 219a is inclined such that it approaches the downstream plate surface 267 from the central side of the main body 268 towards the outer periphery, which is the base end side. Therefore, at the upstream plate surface 266 of the upstream fixed circular plate 219a, the mountain-shaped portion 261 protrudes obliquely relative to the plate surface 266.

[0098] Furthermore, on the upstream side of the fixed circular plate 219a, the protrusion of the mountain 261 on the upstream side plate surface 266 varies depending on the position (phase), but the end ( Figure 6 (a) The upper end) reaches the same height, and the axis relative to the rotor shaft 113 is located on the same vertical plane.

[0099] In contrast, on the downstream side of the fixed circular plate 219a on the upstream side, and on the two sides 266 and 267 of the fixed circular plate 219b on the downstream side, the mountain 261 protrudes approximately perpendicularly to the sides 266 and 267. Furthermore, on these three sides 267, 266, and 267, the amount of protrusion of the mountain 261 is uniform regardless of its position (phase).

[0100] In this embodiment, to avoid making the explanation complicated, the number of hills is nine on each of the plate surfaces 266 and 267. However, it is not limited to this; the number of hills may be eight or less or ten or more. Furthermore, the fixed circular plates 219a and 219b, and the plate surfaces 266 and 267 are not limited to a common number; they may also have different numbers.

[0101] Next, the aforementioned Sigbarn spiral groove 262 will be described. Furthermore, regarding the Sigbarn spiral groove 262, regardless of the differences between the fixed circular plates 219a, 219b, and the plate surfaces 266, 267, all grooves will be labeled with the common reference numeral 262. However, regarding a portion of the Sigbarn spiral groove 262, as described later, there are cases where different reference numerals (262a, etc.) are used to distinguish it from other Sigbarn spiral grooves 262, depending on the situation.

[0102] Between two adjacent hills 261 on each of the plate surfaces 266 and 267, a Sigbarn spiral groove 262 is formed in a spiral shape. This Sigbarn spiral groove 262 is divided by the hills 261. Furthermore, the Sigbarn spiral groove 262, on the upstream plate surface 266 and downstream plate surface 267 of each fixed circular plate 219a and 219b, is formed together with the hills 261, starting from their respective starting points (starting portions) and at the same phase. Moreover, the Sigbarn spiral groove 262 is a space that is relatively wider on the outer periphery (larger opening width) and relatively narrower on the inner periphery (smaller opening width).

[0103] Next, the rotating circular plates 220a to 220c will be described. In this embodiment, the thickness of each of the rotating circular plates 220a to 220c is approximately uniform from the central side near the rotating body 103 to the outer periphery. Furthermore, the thickness relationship between the rotating circular plates 220a to 220c is approximately the same (common). Moreover, the amount of protrusion of the rotating circular plates 220a to 220c from the rotating body 103 is also approximately the same (common), and the rotating circular plates 220a to 220c are axially aligned with their outer periphery end faces covering the entire circumference.

[0104] Furthermore, the rotating circular plates 220a-220c, facing the end portion (protruding end) of the mountain 261, are also divided into Siegbart vortex-shaped grooves 262 with a gap of approximately 1 mm. Additionally, as described above, the upstream side surface 266 of the upstream fixed circular plate 219a is inclined such that it approaches the downstream side surface 267 from the center side of the main body 268 towards the outer periphery, which is the base end side. Furthermore, the most upstream side ( Figure 6The Sigbarn vortex groove 262 between the uppermost rotating circular plate 220a and the upstream side plate surface 266 of the upstream fixed circular plate 219a in (a) is a space that gradually narrows from the outer periphery to the inner periphery.

[0105] Here, regarding the Sigbarn vortex-shaped groove 262 formed on the upstream side plate surface 266 of the fixed circular plate 219a on the upstream side, as mentioned above, the following will distinguish it from other Sigbarn vortex-shaped grooves 262 by the reference numeral 262a.

[0106] Furthermore, the depth of the opening 281 on the upstream side (outer peripheral side) of the Sigbarn vortex-shaped groove 262a is H1, and the depth of the opening 282 on the downstream side (inner peripheral side) is H2. The term "depth" here refers to... Figure 6 The depth in (a) refers to the vertical direction, i.e., the axial direction (consistent with the axial direction of the rotor shaft 113). Furthermore, these depths H1 and H2 are the intervals between the plate surface (reference numerals omitted) of the axially rotating circular plate 220a and the plate surface 266 on the upstream side of the fixed circular plate 219a.

[0107] Furthermore, as described later, the Sigbahn vortex-shaped groove 262a constitutes the gas inlet portion of the groove exhaust mechanism. Therefore, hereinafter, as needed, the Sigbahn vortex-shaped groove 262a may be referred to as the "groove exhaust mechanism inlet portion," "Sigbahn exhaust flow path inlet portion," etc.

[0108] Next, foldback portions 286 and 287 are formed between the rotating circular plates 220a-220c and the fixed circular plates 219a and 219b. These foldback portions 286 and 287 are spatially foldback structures with gas flow paths.

[0109] That is, as described above, the mountain section 261 and the Sigbarn spiral groove section 262 are formed on the two plate surfaces 266 and 267 of the fixed circular plates 219a and 219b as being spatially continuous from their respective starting points (starting points) with the same phase. Therefore, on the inner circumferential side of the fixed circular plates 219a and 219b, a foldback section 286 is formed to spatially connect the Sigbarn spiral groove section 262 of the upstream plate surface 266 and the Sigbarn spiral groove section 262 of the downstream plate surface 267.

[0110] Furthermore, on the outer periphery of the rotating circular plates 220a-220c, a foldback section 287 is also formed, spatially connecting the Sigbarn vortex-shaped grooves 262 on the upstream side (reference numerals omitted) and the Sigbarn vortex-shaped grooves 262 on the downstream side (reference numerals omitted). Moreover, by means of each Sigbarn vortex-shaped groove 262 and each foldback section 286, 287, a spatially continuous gas flow path is formed. Hereinafter, this series of flow paths will be referred to as the "Sigbarn exhaust flow path," as... Figure 6 As shown in (a), the figure is labeled with reference numeral 291.

[0111] Regarding the Sigbarn exhaust flow path 291, the distance between the inner circumferential end face 284 of the fixed circular plates 219a and 219b and the outer circumferential surface 285 of the rotating body 103 is set to a depth H3. Furthermore, this H3 is larger than the aforementioned H2 (the opening size of the opening 282 on the downstream side (inner circumferential side) of the Sigbarn vortex groove 262a).

[0112] Furthermore, the distance between the outer peripheral surface 285 of the rotating circular plates 220a-220c and the spacer 269 of the fixed circular plates is set to a depth H4. This H4 is larger than the aforementioned H2 (the opening size of the opening 282 on the downstream side (inner peripheral side) of the Sigbarn vortex groove 262a). In this embodiment, however, H4 is set to be slightly smaller than the distance between the fixed circular plates 219a, 219b and the rotating body 103, i.e., the depth H3. However, this is not a limitation; H4 may also be set to, for example, be larger than H3.

[0113] Furthermore, the downstream surface 267 of the fixed circular plate 219a on the upstream side and the upstream surface (reference numerals omitted) of the second rotating circular plate 220b from the upstream side face each other approximately parallel to each other. Also, the interval (depth of the gas flow path) between the downstream surface 267 of the fixed circular plate 219a on the upstream side and the second rotating circular plate 220b is set from the inner circumference to the outer circumference (from the inlet to the outlet of the Sigbarn vortex groove 262) to be the same as that described above for H2.

[0114] Furthermore, similarly, the upstream side plate surface 266 of the downstream fixed circular plate 219b and the downstream side plate surface (reference numerals omitted) of the second rotating circular plate 220b from the upstream side face each other approximately parallel to each other. Moreover, the interval (depth of the gas flow path) between the upstream side plate surface 266 of the downstream fixed circular plate 219b and the second rotating circular plate 220b is set from the outer periphery to the inner periphery (from the inlet to the outlet of the Sigbarn vortex groove 262) to be the same as that described above for H2.

[0115] Furthermore, similarly, the downstream side plate surface 267 of the downstream fixed circular plate 219b and the upstream side plate surface (reference numerals omitted) of the third rotating circular plate 220c (from upstream) face each other approximately parallel to each other. Moreover, the interval (depth of the gas flow path) between the downstream side plate surface 267 of the downstream fixed circular plate 219b and the third rotating circular plate 220c is set from the inner circumference to the outer circumference (from the inlet to the outlet of the Sigbarn vortex groove 262) to be the same as that described above for H2.

[0116] That is, the depth of the Sigbahn exhaust flow path 291 gradually narrows from H1 to H2 at the uppermost Sigbahn vortex groove 262a, which serves as the "Sigbahn exhaust flow path inlet". Furthermore, the depth of the Sigbahn exhaust flow path 291 is a constant dimension (H2) in each Sigbahn vortex groove 262 except for the return sections 286 and 287. Thus, the portion of the Sigbahn exhaust flow path 291 where the flow path depth is a constant value (H2) is referred to, for example, as the "constant flow path depth portion of the Sigbahn exhaust flow path 291".

[0117] Furthermore, in this embodiment, the value of the depth H2 of the aforementioned flow path is Ha [mm]. The reason for determining H2 to be Ha [mm] will be explained later. Moreover, referring to depth H2 as "constant" means that, when the unit of measurement is mm (millimeters), it is equal to at least one decimal place without rounding. Therefore, when depth H2 (=Ha) is a number [mm], for example, even if there is unevenness within a range of less than 10% (=±0.1 [mm]), it is equivalent to what is meant here as "constant".

[0118] Furthermore, the starting position of the aforementioned "constant flow depth section of the Sigbarn exhaust flow path 291" (a predetermined position starting from a region where the predetermined depth is continuously constant) is the end (inlet) of the inner circumference side between the fixed circular plate 219a and the second rotating circular plate 220b on the upstream side. Also, the "constant flow depth section of the Sigbarn exhaust flow path 291" is a region where the predetermined depth is continuously constant.

[0119] In the Sigbarn-type exhaust mechanism 201 with this configuration, when the aforementioned motor 121 is driven, the rotating circular plates 220a to 220c rotate. Furthermore, relative rotational displacement occurs between the fixed circular plates 219a and 219b and the rotating circular plates 220a to 220c. Moreover, as... Figure 5 , Figure 6 (b) and Figure 7 As indicated by multiple arrows Q (only some are labeled in the attached diagram), the gas transported by the turbomolecular pump mechanism (composed of rotating blade 102, fixed blade 123, etc.) arrives at the Sigbarn-type exhaust mechanism 201 of the slot exhaust mechanism.

[0120] Furthermore, the gas arriving at the Sigbahn-type exhaust mechanism section 201 flows into the uppermost Sigbahn vortex groove section 262a, which serves as the "Sigbahn exhaust flow path inlet," and passes through a flow path that gradually narrows in the depth direction (axial direction of the rotor shaft 113). The gas then flows into the Holwick-type exhaust mechanism section 301, described later, via the return sections 286 and 287 and the Sigbahn vortex groove section 262 of constant depth.

[0121] Here, the relative rotational directions of the fixed circular plates 219a and 219b and the rotating circular plates 220a to 220c can be referred to as the "tangential direction" when linear, or as the "circumferential direction" when curvilinear.

[0122] Furthermore, the Sigbarn-type exhaust mechanism 201 can be further described in detail. For example, the exhaust flow path formed between the upstream side of the first rotating circular plate 220a and the upstream side plate surface 266 of the upstream fixed circular plate 219a can be referred to as the "flow path of the first Sigbarn-type exhaust mechanism".

[0123] Furthermore, the exhaust flow path formed between the second rotating circular plate 220b and the downstream side plate surface 267 of the upstream fixed circular plate 219a can be referred to as the "flow path of the second Sigbarn-type exhaust mechanism". In addition, the exhaust flow path formed between the second rotating circular plate 220b and the upstream side plate surface 266 of the downstream fixed circular plate 219b can be referred to as the "flow path of the third Sigbarn-type exhaust mechanism".

[0124] Furthermore, the exhaust flow path formed between the downstream surface 267 of the third rotating circular plate 220c and the downstream fixed circular plate 219b can be referred to as the "flow path of the fourth Sigbarn type exhaust mechanism".

[0125] Furthermore, since the Sigbahn-type exhaust mechanism is divided into multiple parts, the Sigbahn-type exhaust mechanism section 201 can be considered to have a multi-layer Sigbahn-type exhaust mechanism. In this case, the "fourth Sigbahn-type exhaust mechanism" is the lowest layer Sigbahn exhaust mechanism.

[0126] Next, the aforementioned Holwick-type exhaust mechanism 301 will be described. The Holwick-type exhaust mechanism 301 is as follows... Figure 5 , Figure 6 As shown in (a), it is mainly composed of the aforementioned threaded spacer 131. The threaded spacer 131 is a cylindrical component with multiple helical threaded grooves 131a engraved on its inner circumferential surface.

[0127] Furthermore, the upper surface 302 of the threaded spacer 131 extends radially (in a direction substantially orthogonal to the axial direction of the rotor shaft 113). Moreover, the upper surface 302 of the threaded spacer 131 faces approximately parallel to the downstream side of the rotating circular plate 220c of the lowest layer of the Sigbarn-type exhaust mechanism section 201 (reference numerals omitted).

[0128] Furthermore, on the upper surface 302 of the threaded spacer 131, similar to the fixing circular plates 219a and 219b of the Sigbarn-type exhaust mechanism 201, a mountain 303 and a vortex-shaped groove 304 are formed. Among them, the mountain 303 is integrally formed and protrudes from the upper surface 302 of the threaded spacer 131.

[0129] Furthermore, the mountain portion 303 is formed in a spiral shape centered on the upper surface 302 of the threaded spacer 131. The mountain portion 303 extends from the periphery (inner periphery) to the outer periphery of the threaded spacer 131 while depicting a smooth curve. The mountain portion 303 protrudes substantially perpendicularly relative to the upper surface 302, and the amount of protrusion of the mountain portion 261 remains substantially uniform regardless of position (phase).

[0130] Furthermore, the number of these mountain sections 303 can be the same as that of the Sigbarn-type exhaust mechanism section 201, for example, nine. However, it is not limited to this; the number of mountain sections 303 can be eight or less or ten or more.

[0131] On the upper surface 302 of the threaded spacer 131, between two adjacent mountain sections 303, the aforementioned spiral groove 304 is formed in a vortex shape. Hereinafter, this vortex-shaped groove 304 will be referred to as the "Holwick vortex-shaped groove 304" to distinguish it from the Sigbarn vortex-shaped groove 262.

[0132] The Holwick vortex-shaped groove 304, like the Siegbarn vortex-shaped groove 262, is divided by a hill 303. Furthermore, the Holwick vortex-shaped groove 304 is configured to form a fold-back portion 287 between itself and the hill 303 on the downstream side of the fixed circular plate 219b of the Siegbarn-type exhaust mechanism 201. Moreover, the Holwick vortex-shaped groove 304 is a space with a relatively large outer peripheral width (larger opening width) and a relatively small inner peripheral width (smaller opening width).

[0133] Furthermore, the Holwick vortex-shaped groove 304 is also divided by the third rotating circular plate 220c from the upstream side of the Sigbarn-type exhaust mechanism 201. Moreover, the spacing between the upper surface 302 of the threaded spacer 131 and the third rotating circular plate 220c is set to be the same as H2 described above, from the inner circumference to the outer circumference (from the inlet to the outlet of the Holwick vortex-shaped groove 304).

[0134] Furthermore, in the Holwick-type exhaust mechanism 301, the aforementioned helical threaded groove 131a is formed on the inner circumferential surface 306 of the threaded spacer 131. This inner circumferential surface 306 faces the outer circumferential surface 307 of the cylindrical portion 102d of the rotating body 103. The distance (depth) between the inner circumferential surface 306 of the threaded spacer 131 and the outer circumferential surface 307 of the cylindrical portion 102d of the rotating body 103 is constant along the entire axial length of the inner circumferential surface 306 (from the upper end to the lower end of the inner circumferential surface 306 in the figure). The value of this distance (depth) is consistent with the aforementioned H2.

[0135] Furthermore, the helical threaded groove 131a and the Hallwick spiral groove 304 are spatially continuous. The connection between the Hallwick spiral groove 304 and the threaded groove 131a can be referred to as a "bend" or the like. In addition, the helical threaded groove 131a reaches the lower end of the inner circumferential surface 306, and the lower end of the inner circumferential surface 306 reaches a position approximately at the same level as the lower end of the outer circumferential surface 307 of the cylindrical portion 102d described above.

[0136] That is, a gas flow path exists between the threaded spacer 131 and the rotating body 103. This gas flow path is formed between the upper surface 302 of the threaded spacer 131 and the outer peripheral surface 307 of the cylindrical portion 102d of the rotating body 103. Figure 6 In the case where the cross-section is represented as in (a), it is L-shaped. Figure 6 (In (a) it is an inverted L shape). The following, as... Figure 6 As shown in (a), the gas flow path is labeled with reference numeral 321, and this series of flow paths is called the "Holwick exhaust flow path".

[0137] The Holwick exhaust flow path 321 is continuous with the aforementioned Sigbarn exhaust flow path 291, receiving gas passing through the Sigbarn exhaust flow path 291. Furthermore, the Holwick exhaust flow path 321 is guided from the outer peripheral side to the inner peripheral side via the receiving Holwick vortex-shaped groove 304, and then, via a bend, into the threaded groove 131a. Subsequently, in the threaded groove 131a, the introduced gas is guided downstream along the threaded groove 131a as the rotating body 103 rotates.

[0138] In the Holwick exhaust flow path 321, the depth is constant at H2. The depth H2 of the Holwick exhaust flow path 321 is consistent with the depth H2 of the constant flow path portion (excluding the part of the Sigbahn exhaust flow path inlet (Sigbahn vortex groove portion 262a), the return portions 286, and 287) of the Sigbahn exhaust mechanism portion 201.

[0139] In other words, the turbomolecular pump 100 can form a region in which the depth of the flow path of the Hallwick type exhaust mechanism 301, namely the Hallwick exhaust flow path 321, is continuously constant at a predetermined depth (H2), and the Sigbahn type exhaust mechanism 201 is continuously constant at a predetermined depth (H2) from a predetermined position as the middle (the end portion of the Sigbahn exhaust flow path inlet (Sigbahn vortex groove 262a)).

[0140] In addition, it is explained here that, apart from the return sections 286 and 287, the depth of the flow path (Sigbahn exhaust flow path 291) of the Sigbahn type exhaust mechanism section 201 and the depth of the flow path (Hallwick exhaust flow path 321) of the Hallwick type exhaust mechanism section 301 are constant (H2).

[0141] However, the depths H3 and H4 of the return portions 286 and 287 can also be narrowed to H2. In this case, a region can be formed in the turbomolecular pump 100 in which the flow path of the slot exhaust mechanism is continuously constant at a predetermined depth (H2) from a predetermined position (the end portion of the Sigbahn exhaust flow path inlet (Sigbahn vortex-shaped slot 262a)).

[0142] Furthermore, as mentioned above, if the Sigbarn-type exhaust mechanism 201 is understood to be divided into multiple layers like the first Sigbarn-type exhaust mechanism to the fourth Sigbarn-type exhaust mechanism, the turbomolecular pump 100 can be such that the flow path depth of at least the lowest Sigbarn-type exhaust mechanism (here, the fourth Sigbarn-type exhaust mechanism) connected to the Holwick-type exhaust mechanism 301 among the multiple Sigbarn-type exhaust mechanisms is continuously constant at a predetermined depth (H2).

[0143] Here, in this embodiment, the term "Siegbahn-type exhaust mechanism" can be used in units of a Siegbahn vortex-shaped groove 262 on the plate surfaces 266 and 267 of one of the fixed circular plates 219a and 219b, or in units of a Siegbahn vortex-shaped groove 262.

[0144] Furthermore, the term "Sigbahn-type exhaust mechanism" can also be used for exhaust mechanisms consisting of flow paths formed by two plate surfaces 266 and 267 spanning the upstream and downstream sides of a fixed circular plate 219a and 219b.

[0145] Furthermore, in this embodiment, as described above, the Hallwick-type exhaust mechanism 301 is explained to perform radial gas transfer with reference to the axis of the rotor shaft 113, and gas transfer in the axial direction of the rotor shaft 113. Furthermore, the Hallwick exhaust flow path 321 is explained in... Figure 6 The cross-section shown in (a) is L-shaped. Figure 6(a) is an inverted L-shape.

[0146] However, the Holwick-type exhaust mechanism section 301 can also be considered as a section that only transports gas in the axial direction toward the rotor shaft 113, and classified as the Sigbarn-type exhaust mechanism section 201, which includes a section that transports gas in the radial direction. Furthermore, in this case, the Sigbarn-type exhaust mechanism section 201 can be considered to have not only the first to fourth Sigbarn-type exhaust mechanisms, but also a fifth Sigbarn-type exhaust mechanism. And in this case, the fifth Sigbarn-type exhaust mechanism is the lowest-level Sigbarn exhaust mechanism.

[0147] In the turbomolecular pump 100 of this embodiment described above, a structure is adopted in which the flow path depth of the Sigbarn-type exhaust mechanism 201 and the flow path depth of the Hallwick-type exhaust mechanism 301 are common constant values ​​(H2). Therefore, it is possible to obtain... Figure 8 The back pressure characteristics are as shown in (a) and (b). Hereinafter, the back pressure characteristics of the turbomolecular pump 100 of this embodiment will be described.

[0148] First, one of the performance characteristics of the vacuum pump, including the turbomolecular pump 100, is the aforementioned "back pressure characteristic." Furthermore, one of the indicators of this "back pressure characteristic" is "back pressure dependence." This "back pressure dependence" is an indicator based on the relationship with the aforementioned auxiliary pump (booster pump) installed downstream of the vacuum pump, indicating the degree to which it is easily affected by back pressure (an indicator of back pressure characteristics considered in another way).

[0149] More specifically, for example, a booster pump (not shown) is configured downstream of the turbomolecular pump 100, thereby allowing the exhaust gas from the turbomolecular pump 100 to be affected by the exhaust gas caused by the booster pump. Furthermore, the performance of the booster pump combined with the turbomolecular pump 100 is not constant and can vary depending on the user of the turbomolecular pump 100. Additionally, the exhaust gas from the turbomolecular pump 100 also varies depending on the diameter and layout of the piping from the turbomolecular pump to the booster pump. The compression ratio, which represents the compression performance of the turbomolecular pump, is the exhaust port pressure / intake port pressure, but the pressure at the intake port 101 of the turbomolecular pump 100 (intake port pressure) that can be reached can vary depending on the pressure of the gas at the exhaust port 133 of the turbomolecular pump 100.

[0150] However, regarding the intake port 101 side of the turbomolecular pump 100, the change in the gas pressure (intake port pressure) at the intake port 101 due to the booster pump or the like combined with the downstream side will also affect the booster pump or the like, which is not preferred.

[0151] Figure 8As described above, (a) and (b) illustrate an example of the relationship between the exhaust port pressure (Pb) and the intake port pressure (Ps) of the turbomolecular pump 100 in this embodiment. Figure 8 In the graphs in (a) and (b), the exhaust pressure (Pb) is represented on a logarithmic scale on the horizontal axis, and the intake pressure (Ps) is represented on a logarithmic scale on the vertical axis. Furthermore, the unit of exhaust pressure (Pb) is [Torr] (the same as [torr] mentioned above), and the unit of intake pressure (Ps) is [mTorr].

[0152] exist Figure 8 In (a) and (b), the change in intake pressure (Ps) on the vertical axis relative to exhaust pressure (Pb) on the horizontal axis, as a back pressure characteristic, is called the "back pressure dependence of intake pressure". Furthermore, Figure 8 (a) represents the back pressure dependence of the intake pressure when the discharged gas is a certain gas (gas A). Figure 8 (b) represents the back pressure dependence of the intake pressure when the discharged gas is set to another type of gas (gas B). Hereinafter, the "back pressure dependence of intake pressure" will be simply referred to as "back pressure dependence".

[0153] Figure 8 In (a), the curves labeled S1 to S7 represent the back pressure dependence curves under different flow rates. Furthermore, the flow rates S1 to S7 are, in order, a given flow rate of 1 sccm, 2 sccm, 3 sccm, 5 sccm, 7 sccm, 9 sccm, and 10 sccm. Moreover, the magnitudes of these flow rates increase in the order of given flow rate 1 to given flow rate 10.

[0154] also, Figure 8 In (b), the reference numerals T1 to T3 also represent the back pressure characteristics (back pressure dependence) under different flow rates. The flow rates of T1 to T3 are respectively a given flow rate of 2 sccm, a given flow rate of 7 sccm, and a given flow rate of 10 sccm.

[0155] Figure 8 In (a), curve S1, represented at the bottom, shows the exhaust pressure (Pb). For example, assuming the origin of the graph is set as the baseline (here, Pb = Ps = 1 [Torr]), the intake pressure (Ps) is approximately midway between 2 [Torr] and 3 [Torr] in the range of 6 [Torr] to over 200 [Torr]. Similarly, for the other curves S2 to S7, constant values ​​are represented at the left end of curves S2 to S7 up to the range where the exhaust pressure (Pb) exceeds 200 [Torr].

[0156] In addition, Figure 8 In (b), the lowest layer represents curve T1, where the exhaust port pressure (Pb) is, for example, similar to... Figure 8 Similarly, assuming the origin of the graph is set as the baseline (here Pb = Ps = 1 [Torr]), the intake pressure (Ps) is approximately constant above 2 [Torr] in the range of 2 [Torr] to over 200 [Torr]. The same applies to curves T2 and T3; the positions from the left end of curves T2 and T3 to the exhaust pressure (Pb) near 200 [Torr] (for T2) and near 20 [Torr] (for T3) represent constant values, respectively.

[0157] Right now, Figure 8 (a) and (b) indicate the existence of a situation where the intake pressure (Ps) remains approximately constant even with changes in the type and flow rate of the gas. Furthermore, it can be said that the larger the range of intake pressure (Ps) and the horizontal lines of the curves represent, the less susceptible the intake pressure is to changes in the exhaust pressure (Pb).

[0158] In other words, for example, it can also be said that, such as Figure 8 As shown in the right-hand portion of curves S1 to S7 for gas A in (a), the larger the pressure range from the slope where the intake pressure (Ps) begins to rise to the exhaust pressure (Pb), the less susceptible the intake pressure is to changes in the exhaust pressure (Pb).

[0159] Compared to the turbomolecular pump 100 constructed in this embodiment, Figure 13 (a) and (b) schematically illustrate an example of the back pressure characteristics of a conventionally constructed turbomolecular pump using a semi-logarithmic scale. Furthermore, Figure 13 (a) and (b) represent the back pressure dependence of the inlet pressure (Ps) as a back pressure characteristic when using different types of gases.

[0160] Among them, Figure 13 Curves U1 to U8 shown in (a) represent the back pressure dependence of a certain gas (gas 1) flow rate from the lower layer of the graph to the following values ​​in order: a given flow rate of 1 sccm, a given flow rate of 3 sccm, a given flow rate of 5 sccm, a given flow rate of 6 sccm, a given flow rate of 7 sccm, a given flow rate of 8 sccm, a given flow rate of 10 sccm, and a given flow rate of 11 sccm. Here, the given flow rate of 11 is a flow rate greater than the given flow rate of 10.

[0161] also, Figure 13 (b) represents curves U11 to U17, which represent information about... Figure 13(a) The back pressure dependence of different types of gas (gas 2) with flow rates from the lower layer of the figure in the order of given flow rate 1 sccm, given flow rate 2 sccm, given flow rate 4 sccm, given flow rate 5 sccm, given flow rate 6 sccm, given flow rate 7 sccm and given flow rate 8 sccm.

[0162] Figure 13 For the gas types shown in (a), the range of the generally flat portion starting from the left end of each curve U1 to U8 shortens as the flow rate increases. Furthermore, for each curve U1 to U8, as shown in the right-hand portion, the outlet pressure (Pb) at which the intake pressure begins to rise decreases as the flow rate increases.

[0163] also, Figure 13 For the gas types shown in (b), the curves U11 to U17 on the graph do not represent flat parts. As the exhaust port pressure increases, the intake port pressure rises according to a cubic curve.

[0164] Right now, Figure 13 In the conventional configurations shown in (a) and (b), the rise in intake pressure (Ps) occurs at a lower exhaust pressure (Pb) compared to the configuration used in the turbomolecular pump 100 of this embodiment. Furthermore, depending on the type of gas, the obtained curves sometimes do not exhibit a flat portion.

[0165] Thus, in conventional designs, it is sometimes difficult to obtain a flat back pressure characteristic curve (here, back pressure dependence), and the range over which the flatness of the back pressure characteristic curve is difficult to ensure is relatively large depending on the gas flow rate. However, according to the turbomolecular pump 100 of this embodiment, as... Figure 8 As illustrated in (a) and (b), a large range of curves can be made flat for back pressure characteristics regardless of the type and flow rate of the gas.

[0166] Furthermore, in the turbomolecular pump 100 of this embodiment, the aforementioned "determined depth" (=H2 (constant value)) of the flow path depth is determined based on the following considerations. Figure 9 This indicates the relationship between the inlet depth and inlet pressure (Pin) of the threaded groove venting mechanism.

[0167] In the turbomolecular pump 100 of this embodiment, the flow path depth of the Hallwick exhaust flow path 321 is constant from the inlet to the outlet (H2) according to the idea described later. Therefore, the "inlet depth" is consistent with the flow path depth of the continuous section of the Hallwick exhaust flow path 321 from the inlet to the outlet. Thus, the relationship of "inlet depth" = "outlet depth" holds true.

[0168] Furthermore, in the Hallwick exhaust flow path 321, the gas is compressed while being transported, but the "inlet depth" is desired to be determined to improve the compression efficiency of the Hallwick exhaust flow path 321. Moreover, in the simulation experiments conducted by the inventors, Figure 9 A lower value of the vertical axis pressure Pin[Torr] indicates a lower "inlet depth" and can be considered a "inlet depth" with high compression efficiency.

[0169] In the simulation experiments conducted by the inventor, like Figure 9 As is generally the case in the experimental model, the pressure Pin initially decreases gradually with increasing "inlet depth". However, the pressure P is lowest at a "inlet depth" of Ha [mm], and thereafter, the pressure P increases with increasing "inlet depth".

[0170] Furthermore, based on the experimental results, Ha, which is a constant value, is determined to be the value at which the pressure Pin [Torr] decreases the most. Also, a common depth (H2) is used as Ha for the entire Holwick exhaust flow path 321 and the portion after the inlet of the Sigbarn exhaust flow path 319.

[0171] Furthermore, the optimal constant value (H2) of the flow path depth varies depending on factors such as the operating speed of the turbomolecular pump 100 and the diameter of associated parts (fixed circular plates 219a, 219b, rotating circular plates 220a to 220c, etc.). Therefore, it is desirable to determine the optimal flow path depth (H2) as the peak value of exhaust performance (including compression performance) based on these factors. The flow path depth is typically designed in the range of approximately 2 mm to 10 mm (more preferably 3 mm to 5 mm).

[0172] Furthermore, in the turbomolecular pump 100 of this embodiment, regarding Figure 8 The explanations for improving back pressure characteristics, as in (a) and (b), are not entirely sufficient and require further investigation. Figure 10 The modeling shown is illustrated below.

[0173] Figure 10 This diagram is used to illustrate the characteristics of a general slot exhaust mechanism, but here, as an explanation of this embodiment, the slot exhaust mechanism of the turbomolecular pump 100 will be used. Figure 6 (a) will be used to illustrate this. As described above, the slot exhaust mechanism of the present invention includes a Sigbarn-type exhaust mechanism 201 and a Hallwick-type exhaust mechanism 301. Furthermore, the inlet portion (Sigbarn exhaust flow path inlet portion) of the slot exhaust mechanism becomes narrower towards the depth of the flow path, and is composed of a Sigbarn vortex-shaped slot portion 262a with a flow path depth of H2.

[0174] and, Figure 10In the model shown, the part corresponding to the slot exhaust mechanism is labeled with reference numeral 321. For convenience, one end of it (the upper end in the figure) is labeled with the same reference numeral as the Sigbahn vortex slot, which is the inlet of the Sigbahn exhaust flow path, namely "262a".

[0175] also, Figure 10 In the model shown, reference numeral 322 indicates a fixed model in which the fixed circular plates 219a and 219b constituting the Sigbarn exhaust flow path 291 and the threaded spacer 131 constituting the Holwick exhaust flow path 321 are combined and then split in half. Furthermore, reference numeral 323 indicates a rotating model in which the rotating body 103, which has rotating circular plates 220a to 220c having the Sigbarn exhaust flow path 291, is split in half.

[0176] Furthermore, in the figure, reference numeral K indicates the axis of rotation, and arrow J indicates that the rotating model 323 rotates around the axis of rotation K. Additionally, reference numeral H1, as previously stated, indicates the depth (flow path depth) of the opening 281 on the upstream side (outer peripheral side) of the Siegbarn vortex groove 262a. Furthermore, reference numeral H2 indicates the constant flow path depth of the aforementioned Siegbarn exhaust flow path 291 and the constant value of the flow path depth of the Holwick exhaust flow path 321.

[0177] Figure 11 (a) and (b) are used to illustrate Figure 10 The diagram shows the exhaust performance of the models with varying flow path depths. Among them, Figure 11 In graph (a), the horizontal axis represents "flow path position" and the vertical axis represents "flow path depth". The "flow path position" on the horizontal axis indicates the location within the slot exhaust mechanism 311. Furthermore, "increased flow path position" is used here to represent the change in the observation point from the inlet of the slot exhaust mechanism 311 (…). Figure 10 (upper end) towards the outlet ( Figure 10 (The lower end) moves.

[0178] Figure 11 In (a), the solid line V1 represents Figure 10 The model shown illustrates the relationship between the flow path location and flow path depth. Additionally, the dashed line W1 represents the relationship between the flow path location and flow path depth in previously constructed models.

[0179] The previous configuration described here, as shown by the dashed line W1, shows that as the flow path position increases, the flow path depth gradually decreases. In contrast, in... Figure 10 In the model shown, as indicated by the solid line V1, at the inlet 262a (Siegbahn exhaust flow path inlet) of the slot exhaust mechanism 311, the flow path depth is drastically reduced compared to the conventional structure as the flow path position increases.

[0180] However, when the flow path position is further increased and the observation point enters the constant flow path depth section of the Sigbarn exhaust flow path 291 through the inlet 262a of the slot exhaust mechanism section 311, the flow path depth remains constant (H2). Furthermore, even if the flow path position is increased (entering the Holwick exhaust flow path 321), the flow path depth remains constant (H2).

[0181] In the conventional configuration where the depth of the flow path from the inlet to the outlet of the exhaust mechanism 311 gradually decreases, there is a potential to improve exhaust performance such as "exhaust velocity" and "compression performance," making it easier to improve exhaust performance. However, there is also a possibility of gas backflow, so it is necessary to continuously and smoothly exhaust (transfer) the intake gas.

[0182] In contrast, as shown by the solid line V1 obtained by modeling the turbomolecular pump of this embodiment, the depth of the flow path remains constant, thereby making it easy to prevent backflow with a simple design.

[0183] also, Figure 11 In graph (b), the horizontal axis represents "flow path location," and the vertical axis represents "pressure." The horizontal axis representing "flow path location" and... Figure 11 (a) is the same. In addition, the "pressure" on the vertical axis represents the pressure of the gas within the flow path.

[0184] exist Figure 11 In (b), the dashed line W2 represents an idealized pressure change. The pressure change shown by dashed line W2 increases with increasing flow path position at a constant rate. Furthermore, dashed line W3 represents a pressure change occurring when gas backflow, as described above, causes a decrease in exhaust performance. The pressure change shown by dashed line W3 increases with increasing flow path position at a smaller slope than that of W2.

[0185] Relative to them, the solid line V2 represents Figure 10 The model shows pressure changes. Figure 10 In the model, at the inlet of the venting mechanism (venting mechanism inlet, Sigbarn vortex vent 262a), the pressure increases sharply compared to W2 and W3 as the flow path position increases. Furthermore, in this section, the degree of gas compression is significantly enhanced.

[0186] Furthermore, the rate of change decreases thereafter, but the pressure gradually increases with the increase of the flow path position. Also, when the observation point enters the constant flow path depth section of the Sigbarn exhaust flow path 291 through the inlet 262a of the slot exhaust mechanism 311, the flow path depth is a constant value (H2). Furthermore, the pressure at the outlet of the slot exhaust mechanism 311 is a value between W2 and W3 as described above.

[0187] That is, such as Figure 10As shown in the model, when the depth of the flow path in the slot exhaust mechanism 311 is kept constant from the middle (flow path position) (H2), the compression performance is limited and does not improve significantly. However, gas backflow is unlikely to occur, and the pressure from the middle to the end of the slot exhaust mechanism 311 can be close to the ideal pressure, i.e., W2.

[0188] Clearly, the compression performance can be improved by further extending the flow path depth H2.

[0189] Furthermore, even if the region with a constant flow path depth (H2) does not achieve the peak of compressibility performance, it is desirable to ensure that gas backflow within the flow path is as infrequent as possible (or as difficult to occur).

[0190] The countercurrent of the aforementioned gases can be explained as follows. Figure 12 (a) represents the flow-related model of the Courbet-Poiseuille equation between parallel plates. Here, we first consider steady flow between two parallel plates. One plate is stationary, and the other moves at a velocity u. Thus, the Navier-Stokes equations are simplified to the following equation (Equation 1).

[0191] Formula 1

[0192]

[0193] Here, in Equation 1, u is a function of only y and p is a function of only x. Therefore, it directly becomes an ordinary differential equation (Equation 2).

[0194] Formula 2

[0195]

[0196] The boundary conditions are y = 0: u = 0 and y = h: u = U.

[0197] The solution can be easily obtained by integration, as shown in Equation 3.

[0198] Formula 3

[0199]

[0200] Its solution is the sum of simple shear flow (first term, Cuyet flow) and parabolic velocity distribution (second term, Poiseuille flow).

[0201] Dividing both sides of Equation 3 by U, we get Equation 4.

[0202] Formula 4

[0203]

[0204] Here, the equation is modified according to the sign of the dimensionless pressure slope (Equation 5) in the second term on the right side of Equation 4, as follows: Figure 12 As shown in graph (b), P produces a countercurrent section with a negative u / U ratio at -1 hour.

[0205] Formula 5

[0206]

[0207] Furthermore, according to equations 4 and 5, the countercurrent component increases as h increases. That is, it can be said that when the flow path depth increases, there is a tendency for countercurrent to occur.

[0208] As explained above, in the turbomolecular pump 100 according to this embodiment, the flow path depth from the middle of the Siegbarn-type exhaust mechanism 201 to the outlet of the Hallwick-type exhaust mechanism 301 is continuously kept constant (H2) in the slot exhaust mechanism section. Therefore, as... Figure 8 As shown in (a) and (b), excellent back pressure characteristics are achieved. Therefore, according to this embodiment, a turbomolecular pump 100 with excellent exhaust performance can be provided.

[0209] Furthermore, in the venting mechanism section, such as Figure 5 and Figure 6 As shown in (a), the Sigbarn-type exhaust mechanism section 201 and the Holwick-type exhaust mechanism section 301 are continuously formed, and the exhaust flow path of the slotted exhaust mechanism section is formed by means of the Sigbarn-type exhaust mechanism section 201 and the Holwick-type exhaust mechanism section 301. Therefore, compared with the case of having only one of the Sigbarn-type exhaust mechanism section 201 and the Holwick-type exhaust mechanism section 301, it is easy to ensure a longer exhaust flow path. Furthermore, it is also possible to provide a turbomolecular pump 100 with excellent exhaust performance.

[0210] Furthermore, in the Sigbahn-type exhaust mechanism section 201, multiple flow paths (flow paths of the first to fourth Sigbahn-type exhaust mechanisms) are spatially connected via turnback sections 286 and 287 to form the Sigbahn exhaust flow path 291. And, the Sigbahn-type exhaust mechanism section 201 as... Figure 5 and Figure 6 (a) shows a meandering flow path. Therefore, the Siegbahn exhaust flow path 291 can be easily extended. Furthermore, this also allows for the provision of a turbomolecular pump 100 with excellent exhaust performance.

[0211] Furthermore, while it is understandable that the presence of the reversing sections 286 and 287 could easily lead to gas backflow and stagnation, thus degrading performance, it is believed that by making the gas flow path as long as possible, backflow and stagnation can be prevented as much as possible. In addition, due to the drag effect of the gas flow at the reversing sections 286 and 287, pressure drop does not occur, or even if it does occur, it will not result in an excessive pressure drop.

[0212] Furthermore, the Hallwick exhaust flow path 321 of the Hallwick type exhaust mechanism 301 is as follows: Figure 5 and Figure 6 As shown in (a), it is formed in an L-shape in cross-section. Therefore, compared to the case where the exhaust flow path is formed only on the inner circumferential surface 306 of the threaded spacer 131, it is possible to ensure that the length of the Hallwick vortex groove 304 is increased. Furthermore, this also enables the provision of a turbomolecular pump 100 with excellent exhaust performance.

[0213] Furthermore, in this embodiment, as Figure 5 and Figure 6 As shown in (a), the slot exhaust mechanism is spatially continuous in the layer below (downstream side) of the turbomolecular pump mechanism, which consists of rotating blades 102 (102a, 102b, 102c...) and fixed blades 123 (123a, 123b, 123c...). Therefore, by utilizing the exhaust flow paths of the slot exhaust mechanism and the turbomolecular pump mechanism, a longer exhaust flow path can be easily formed. Furthermore, this allows for the provision of a turbomolecular pump 100 with excellent exhaust performance.

[0214] Furthermore, the turbomolecular pump 100 of this embodiment can also be described as follows. By ensuring a longer gas flow path, as in the turbomolecular pump 100, and making the opening width and depth common, the volume of the space used for gas flow (the space containing gas per unit time) is generally increased. This is considered one of the factors that improves back pressure characteristics by ensuring a longer gas flow path.

[0215] That is, such as Figure 11 As shown by the dashed line W1 in (a), when the flow path depth changes from the inlet to the outlet of the slot exhaust mechanism, the exhaust performance, including "exhaust velocity" and "compression performance," improves, as previously mentioned. However, regarding "back pressure characteristics," if a larger flow path length can be ensured, the effect of the change in flow path depth from the inlet to the outlet of the slot exhaust mechanism is mitigated. Therefore, it is believed that by increasing the flow path length of the slot exhaust mechanism, exhaust performance will be improved gradually, resulting in good "back pressure characteristics."

[0216] In addition, such as Figure 8As shown in (a) and (b), one of the factors that enables the achievement of excellent back pressure characteristics is to suppress the arrival pressure by means of the Sigbarn vortex groove 262a (groove exhaust mechanism inlet), which serves as the inlet of the groove exhaust mechanism.

[0217] That is, the arrival pressure is a factor related to the compression ratio; generally, a higher compression ratio results in a lower arrival pressure. Furthermore, as the inlet of the slot exhaust mechanism, a Sigbarn vortex-shaped slot 262a is provided, thereby ensuring a larger opening at the inlet compared to a constant depth (H2), which can increase the compression ratio and reduce the arrival pressure.

[0218] In addition, such as Figure 8 As shown in (a) and (b), in addition to keeping the flow path depth constant (H2) and ensuring a large opening at the inlet by means of the Sigbarn vortex groove 262a, the Sigbarn exhaust flow path 291 also has a foldback section 286, 287 formed.

[0219] That is, this setting also achieves the following effect: due to the pressure distribution at the return sections 286 and 287, the gas in the Sigbarn exhaust flow path 291 is less likely to be affected by stagnation or backflow.

[0220] Here, gas retention and backflow are the causes of decreased exhaust performance. Furthermore, as causes of retention (such as localized retention within the flow path), narrowing of the flow path and decreased conductivity can be listed. In addition, as causes of backflow, a negative pressure slope can be listed.

[0221] Furthermore, in the turbomolecular pump 100 of this embodiment, the Sigbarn exhaust flow path 291 is formed in multiple layers in an axial (rotor shaft 113) manner by overlapping via the foldback portions 286 and 287. Additionally, in the Hallwick type exhaust mechanism 301, the Hallwick exhaust flow path 321 is formed in an L-shape in cross-section.

[0222] Therefore, by arranging the Sigbarn-type exhaust mechanism 201 and the Holwick-type exhaust mechanism 301 axially, the overall size (height dimension) of the axial turbomolecular pump 100 can be minimized as much as possible.

[0223] In addition, regarding the Sigbarn vortex groove 262 and the Holwick vortex groove 304, if the flow path is excessively enlarged, backflow is likely to occur, so it is desirable to determine the appropriate width and area of ​​the flow path.

[0224] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and can be modified in many ways. For example, the number of fixed circular plates is not limited to 2, and the number of rotating circular plates is not limited to 3.

[0225] Furthermore, the objects forming the mountain portion 261 and the groove portion 262 are not limited to the fixed circular plates 219a and 219b, but can also be the rotating circular plates 220a to 220c. Furthermore, the fixed circular plates and rotating circular plates with the mountain portion 261 and the groove portion 262 formed can be mixed together. For example, the mountain portion 261 and the groove portion 262 can be formed on one side of the rotating circular plate and one side of the fixed circular plate, respectively. Furthermore, the mountain portion 261 and the groove portion 262 can be provided on one side of the fixed circular plate facing the rotating circular plate, separated from the upper and lower (upstream and downstream) sides of the rotating circular plate.

[0226] This invention is not limited to the above-described embodiments. As long as it is within the scope of the technical concept of this invention, various modifications can be made based on the usual creative ability of those skilled in the art.

[0227] Explanation of reference numerals in the attached figures

[0228] 100 turbomolecular pump (vacuum pump)

[0229] 102 Rotary Wing

[0230] 102d cylindrical section (rotating cylinder)

[0231] 123 Fixed-wing

[0232] 131 Threaded spacer (fixed cylinder)

[0233] 131a threaded groove

[0234] 201 Sigbarn type exhaust mechanism (Sigbarn exhaust mechanism)

[0235] 301 Holwick type exhaust mechanism (Holwick exhaust mechanism)

[0236] 219a, 219b Fixed circular plates

[0237] 220a~220c Rotating Circular Plate

[0238] 262 Sigbarn spiral groove (spiral groove)

[0239] H2 has a constant flow path depth (a predetermined depth).

Claims

1. A vacuum pump comprising a Siegbarn exhaust mechanism having vortex-shaped grooves on at least one of a rotating circular plate and a fixed circular plate, and a Hallwick exhaust mechanism having helical grooves on at least one of a rotating cylinder and a fixed cylinder, wherein the Hallwick exhaust mechanism is disposed downstream of the Siegbarn exhaust mechanism, the vacuum pump being characterized in that... The flow path depth of the aforementioned Holwick exhaust mechanism is continuously constant at a predetermined depth, and the aforementioned Sigbarn exhaust mechanism has a region that is continuously constant at the aforementioned predetermined depth from a predetermined position. Equipped with the aforementioned multi-layered Siegbarn exhaust system, The flow path depth of at least the lowest of the aforementioned Sigbarn exhaust mechanisms, which is connected to the aforementioned Holwick exhaust mechanism, is continuously constant at the aforementioned predetermined depth.

2. The vacuum pump as described in claim 1, characterized in that, The upstream side of the aforementioned Sigbarn exhaust mechanism has a rotating wing and a fixed wing. The aforementioned rotary wing has a wing array, The aforementioned fixed wing is configured to be spaced at a predetermined interval from the aforementioned rotating wing in the axial direction.

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