Vacuum pump and rotary blade for vacuum pump

Abstract

The present invention provides a vacuum pump and a rotary blade for the vacuum pump that can effectively suppress the accumulation of reaction products. The vacuum pump comprises a rotating shaft (113) held rotatably, a driving mechanism for the rotating shaft (113), a first rotary blade (201) formed of a first material, a second rotary blade (202) formed of a second material having higher heat resistance than the first material and arranged downstream of the first rotary blade (201), and a housing (204) housing the rotating shaft (113), the first rotary blade (201), and the second rotary blade (202). The vacuum pump is characterized in that the second rotary blade (202) is arranged on the first rotary blade (201) via a heat insulating portion (203).

Description

Technical Field

[0001] The present invention relates to a vacuum pump and a rotary blade for the vacuum pump. Background Art

[0002] Semiconductor manufacturing equipment, liquid crystal manufacturing equipment, electron microscopes, surface analysis equipment, precision processing equipment, etc. require a high vacuum state within the equipment. To achieve a high vacuum state within these equipment, a vacuum pump is used.

[0003] To prevent the accumulation of reaction products from semiconductor manufacturing and other processes within vacuum pumps, research is underway to maintain the temperature of the pull pump mechanism, located downstream of the vacuum pump, above the sublimation temperature of the reaction products. However, depending on the semiconductor manufacturing process, the sublimation temperature of the reaction products may be high, making accumulation impossible to prevent. In such cases, the pull pump mechanism must be periodically disassembled and cleaned, a time-consuming and costly operation.

[0004] Therefore, Patent Document 1 studies a technique for maintaining a high temperature at a portion where reaction products accumulate by replacing a portion on the downstream side of a rotor blade with a material having high heat resistance.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-71139. Summary of the Invention

[0006] While the technology described in Patent Document 1 appears to maintain a high temperature in the downstream portion of the vacuum pump, in reality, a large amount of heat flows from the high-temperature downstream portion to the low-temperature upstream portion, potentially causing the low-temperature portion to exceed the allowable temperature. Consequently, the temperature in the downstream portion of the vacuum pump cannot be sufficiently raised, leading to the accumulation of reaction products.

[0007] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a vacuum pump and a vacuum pump rotor capable of effectively suppressing accumulation of reaction products.

[0008] The vacuum pump of the present invention for achieving the above-mentioned purpose comprises a rotating shaft held so as to be rotatable, a driving mechanism for the rotating shaft, a first rotary blade formed of a first material, a second rotary blade formed of a second material having higher heat resistance than the first material and arranged downstream of the first rotary blade, and a casing in which the rotating shaft, the first rotary blade and the second rotary blade are housed. The vacuum pump is characterized in that the second rotary blade is arranged on at least one of the rotating shaft or the first rotary blade via a heat insulating portion.

[0009] The vacuum pump rotor of the present invention for achieving the above-mentioned object includes a first rotor and a second rotor, wherein the first rotor is formed of a first material, and the second rotor is formed of a second material having higher heat resistance than the first material, and is arranged downstream of the first rotor. The vacuum pump rotor is characterized in that the second rotor is arranged on the first rotor via a heat insulating portion.

[0010] Effects of the Invention

[0011] In the vacuum pump and vacuum pump rotor configured as described above, the second rotor blade, located downstream of the first rotor blade, is disposed via a heat insulator. Therefore, even if the second rotor blade on the downstream side reaches a high temperature, heat inflow to the first rotor blade on the upstream side is reduced. Consequently, overheating of the first rotor blade on the upstream side can be suppressed, while the second rotor blade on the downstream side can be kept at a high temperature, thereby suppressing the accumulation of reaction products within the vacuum pump. Furthermore, the second rotor blade disposed via a heat insulator relative to at least one of the rotating shaft and the first rotor blade may not only be disposed directly via the heat insulator but may also be disposed indirectly via a portion or component other than the heat insulator.

[0012] The heat insulating portion may be formed of a third material having a lower thermal conductivity than the first material and the second material. Thus, the heat insulating portion formed of the third material can effectively suppress the inflow of heat from the second rotor to the first rotor.

[0013] The third material may be a porous material. In this way, the heat inflow from the second rotor to the first rotor can be effectively suppressed by the heat insulating portion formed of the porous material with low thermal conductivity.

[0014] The third material may be stainless steel or titanium alloy. In this way, the heat inflow from the second rotor to the first rotor can be effectively suppressed by the heat insulating portion formed of stainless steel or titanium alloy having low thermal conductivity.

[0015] The third material may be ceramic. In this way, the heat inflow from the second rotor to the first rotor can be effectively suppressed by the heat insulating portion formed of ceramic having low thermal conductivity.

[0016] The third material may be a resin material. In this way, the heat insulating portion formed of the resin material having low thermal conductivity can effectively suppress the inflow of heat from the second rotor to the first rotor.

[0017] The heat insulating portion may be a heat insulating structure formed with a predetermined length and thickness. Thus, the heat insulating portion having the heat insulating structure formed with a predetermined length and thickness can effectively suppress the inflow of heat from the second rotor to the first rotor.

[0018] Alternatively, the first rotor may include a plurality of rows of rotary blades disposed on a side surface thereof, and the vacuum pump may include a row of stationary blades disposed between the rows of rotary blades. The rows of rotary blades and the rows of stationary blades may form a turbomolecular pump mechanism. This allows efficient exhaust down to relatively low pressures.

[0019] Alternatively, the second rotor may include at least one rotating cylindrical portion disposed thereon, and the vacuum pump may include at least one stationary cylindrical portion disposed opposite the outer or inner circumference of the rotating cylindrical portion, wherein the rotating cylindrical portion and the stationary cylindrical portion form a Holweck-type pull pump mechanism. This allows for efficient exhaust even when the pressure near the exhaust port of the pump is relatively high.

[0020] Alternatively, the second rotor may include at least one rotating circular plate portion disposed on a side surface thereof, and the vacuum pump may include at least one stationary circular plate portion disposed opposite an axially facing surface of the rotating circular plate portion, with the rotating and stationary circular plates forming a Sigbarn-type traction pump mechanism. This allows for efficient exhaust even when the pressure near the pump's exhaust port is relatively high.

[0021] The first rotor may be configured so that at least a portion thereof projects downstream from the heat insulating portion. This increases the surface area of ​​the first rotor and promotes heat dissipation from the first rotor to components disposed facing the surface of the first rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a longitudinal sectional view of the vacuum pump.

[0023] Figure 2 It is the circuit diagram of the amplification loop.

[0024] Figure 3 This is a timing chart showing control when the current command value is larger than the detected value.

[0025] Figure 4 This is a timing chart showing control when the current command value is smaller than the detected value.

[0026] Figure 5 It is a longitudinal sectional view of the vacuum pump of the first embodiment.

[0027] Figure 6 It is a longitudinal sectional view of the vacuum pump of the second embodiment.

[0028] Figure 7 It is a longitudinal sectional view of the vacuum pump of the third embodiment.

[0029] Figure 8It is a longitudinal sectional view of a vacuum pump according to a fourth embodiment. DETAILED DESCRIPTION

[0030] The following describes embodiments of the present invention with reference to the accompanying drawings. For ease of explanation, the dimensions in the drawings may be exaggerated and differ from actual dimensions. Furthermore, in this specification and the accompanying drawings, components having substantially the same functional structure are denoted by the same reference numerals to omit overlapping descriptions.

[0031] <First embodiment>

[0032] The vacuum pump according to the first embodiment of the present invention is a turbomolecular pump 100 that ejects gas by flinging gas molecules with the rotating blades of a high-speed rotating rotor. The turbomolecular pump 100 is used, for example, to draw gas from a chamber in a semiconductor manufacturing device and exhaust it.

[0033] The longitudinal cross-sectional view of the turbomolecular pump 100 is shown in FIG. Figure 1 Indicated in. Figure 1 In the present invention, the turbomolecular pump 100 has an air intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Furthermore, a rotor 103 is provided inside the outer cylinder 127. The rotor 103 has a plurality of rotating blades 102 (102a, 102b, 102c, etc.) radially and multilayered around its circumference, serving as turbine blades for sucking and discharging gas. A rotating shaft 113 is mounted at the center of the rotor 103. This shaft 113 is suspended in mid-air and positionally controlled, for example, by a five-axis magnetic bearing.

[0034] The upper radial electromagnets 104 are four electromagnets arranged in pairs along the X-axis and the Y-axis. Four upper radial sensors 107 are provided near each of the upper radial electromagnets 104, corresponding to each of the upper radial electromagnets 104. The upper radial sensors 107 utilize, for example, an inductance sensor or an eddy current sensor having a conductive winding. The upper radial sensors 107 detect the position of the rotating shaft 113 based on changes in the inductance of the conductive winding that vary with the position of the rotating shaft 113. The upper radial sensors 107 are configured to detect radial displacement of the rotating shaft 113, that is, the rotating body 103 fixed to the rotating shaft 113, and transmit this information to a control device (not shown).

[0035] In the control device, for example, a compensation loop having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on a position signal detected by the upper radial sensor 107. Figure 2 An amplifier circuit 150 (described later) shown in FIG. 1 performs excitation control on the upper radial electromagnet 104 based on the excitation control command signal, thereby adjusting the upper radial position of the rotating shaft 113 .

[0036] The rotating shaft 113 is formed from a high-permeability material (such as iron or stainless steel) 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. Furthermore, the lower radial electromagnet 105 and lower radial sensor 108 are configured similarly to the upper radial electromagnet 104 and upper radial sensor 107, allowing the lower radial position of the rotating shaft 113 to be adjusted in the same manner as the upper radial position.

[0037] Furthermore, axial electromagnets 106A and 106B are arranged so as to sandwich a disc-shaped metal disk 111 provided at the bottom of rotating shaft 113. Metal disk 111 is made of a high-permeability material such as iron. An axial sensor 109 is provided to detect axial displacement of rotating shaft 113, and its axial position signal is transmitted to the control device.

[0038] In addition, in the control device, for example, a compensation loop with a PID adjustment function generates respective excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplification circuit 150 performs excitation control on the axial electromagnet 106A and the axial electromagnet 106B respectively based on these excitation control command signals. As a result, the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disk 111 downward, and the axial position of the rotating shaft 113 is adjusted.

[0039] In this way, the control device appropriately adjusts the magnetic force applied by the axial electromagnets 106A and 106B to the metal disk 111, magnetically levitating the rotating shaft 113 in the axial direction and spatially holding it contactlessly. The amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

[0040] Meanwhile, motor 121 includes a plurality of magnetic poles arranged circumferentially around rotating shaft 113. Each magnetic pole is controlled by a control device so that electromagnetic forces acting between the magnetic poles and rotating shaft 113 drive rotating shaft 113. Furthermore, a rotational speed sensor (not shown) such as a Hall effect element, resolver, or encoder is incorporated into motor 121, and the rotational speed of rotating shaft 113 is detected using detection signals from the rotational speed sensor.

[0041] Furthermore, for example, a phase sensor (not shown) is mounted near the lower radial sensor 108 to detect the rotation phase of the rotating shaft 113. The control device uses the detection signals of the phase sensor and the rotation speed sensor together to detect the position of the magnetic pole.

[0042] A plurality of stationary blades 123a, 123b, 123c, etc. are arranged with slight gaps between the rotating blades 102 (102a, 102b, 102c, etc.). The rotating blades 102 (102a, 102b, 102c, etc.) are formed to be inclined at a predetermined angle from a plane perpendicular to the axis of the rotating shaft 113 in order to move exhaust gas molecules downward through collision.

[0043] Furthermore, the stationary blades 123 are similarly formed to be inclined at a predetermined angle from a plane perpendicular to the axis of the rotating shaft 113, and are arranged inside the outer cylinder 127, alternating with the layers of the rotating blades 102. Furthermore, the outer peripheral ends of the stationary blades 123 are supported by being inserted between a plurality of stacked stationary blade spacers 125 (125a, 125b, 125c, etc.).

[0044] The stationary blade spacer 125 is an annular member made of a metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals. An outer cylinder 127 is fixed to the outer periphery of the stationary blade spacer 125 with a slight gap therebetween. A base portion 129 is provided at the bottom of the outer cylinder 127. An exhaust port 133 is formed on the base portion 129, which communicates with the outside and enters the intake port 101 from the cavity side. Exhaust gas transferred to the base portion 129 is then sent 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 portion of the stationary blade spacer 125 and the base 129. The threaded spacer 131 is a cylindrical component made of a metal such as aluminum, copper, stainless steel, iron, or an alloy thereof. Multiple spiral thread grooves 131a are engraved on its inner circumference. The spiral direction of the thread grooves 131a is such that exhaust gas molecules are transferred toward the exhaust port 133 as they move in the rotational direction of the rotor 103. A rotating cylindrical portion 102d extends downward from the lowest portion of the rotor 103, continuous with the rotating blades 102 (102a, 102b, 102c, etc.). The outer circumference of this rotating cylindrical portion 102d is cylindrical and extends toward the inner circumference of the threaded spacer 131, remaining adjacent to the inner circumference of the threaded spacer 131 with a predetermined gap therebetween. The exhaust gas transferred to the thread groove 131 a by the rotating blades 102 and the stationary blades 123 is guided by the thread groove 131 a and sent to the base portion 129 .

[0046] The base 129 is a disc-shaped component that forms the base of the turbomolecular pump 100 and is generally made of a metal such as iron, aluminum, or stainless steel. The base 129 physically holds the turbomolecular pump 100 and also serves as a heat conduction path. Therefore, it is desirable to use a metal such as iron, aluminum, or copper that is rigid and has high thermal conductivity.

[0047] In this structure, when the rotary blades 102 and the rotating shaft 113 are rotated by the motor 121, the exhaust gas is drawn from the chamber through the air inlet 101 by the action of the rotary blades 102 and the stationary blades 123. The exhaust gas drawn from the air inlet 101 passes between the rotary blades 102 and the stationary blades 123 and is transferred to the base portion 129. At this time, the temperature of the rotary blades 102 rises due to frictional heat generated when the exhaust gas contacts the rotary blades 102 and heat conducted by the motor 121. However, this heat is transferred to the stationary blades 123 through radiation or conduction through gas molecules in the exhaust gas.

[0048] The stationary blade spacers 125 are joined to each other at their outer circumferences, and transfer heat received by the stationary blades 123 from the rotary blades 102 , frictional heat generated when exhaust gas contacts the stationary blades 123 , and the like to the outside.

[0049] In the above description, the threaded spacer 131 is arranged on the outer circumference of the rotating cylindrical portion 102d of the rotating body 103, and the threaded groove 131a is engraved on the inner circumference of the threaded spacer 131. However, there is also a case where the threaded groove is engraved on the outer circumference of the rotating cylindrical portion 102d, and a spacer having a cylindrical inner circumference is arranged around the threaded groove.

[0050] In addition, depending on the purpose of the turbomolecular pump 100, there is also the following situation: the electrical equipment part will be covered by the stator column 122 so that the gas sucked from the intake port 101 will not enter the electrical equipment part composed of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A, 106B, the axial sensor 109, etc., and the stator column 122 is maintained at a predetermined pressure by means of flushing gas.

[0051] In this case, a pipe (not shown) is provided at the base portion 129, and flushing gas is introduced through this pipe. The introduced flushing gas passes through the gaps between the protective bearing 120 and the rotating shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotating blade 102, and is then delivered to the exhaust port 133.

[0052] Here, the turbomolecular pump 100 requires control based on the inherent parameters (for example, a number of characteristics corresponding to the model) that are determined and adjusted separately for each model. In order to store these control parameters, the turbomolecular pump 100 is equipped with an electronic circuit unit 141 in its main body. The electronic circuit unit 141 is composed of a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting the components. The electronic circuit unit 141 is housed below the rotational speed sensor (not shown in the figure), for example, near the center of the base unit 129, and is closed by an airtight bottom cover 145. The base unit 129 constitutes the lower part of the turbomolecular pump 100.

[0053] However, in the semiconductor manufacturing process, the process gas introduced into the chamber contains substances that solidify when their pressure exceeds a predetermined value or their temperature drops below a predetermined value. Within the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. If the process gas's pressure rises above a predetermined value or its temperature drops below a predetermined value while being transferred from the intake port 101 to the exhaust port 133, the process gas solidifies and accumulates within the turbomolecular pump 100.

[0054] For example, when SiCl4 is used as the process gas in an Al etching device, it can be seen from the vapor pressure curve that low vacuum (760[torr]~10 -2 When the temperature is high (about 20°C) and the pressure is low (about 20°C), solid products (such as AlCl3) precipitate and accumulate inside the turbomolecular pump 100. As a result, when process gas precipitates accumulate inside the turbomolecular pump 100, the accumulation narrows the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. Furthermore, the aforementioned products are prone to solidification and accumulation in high-pressure areas near the exhaust port and the threaded spacer 131.

[0055] Therefore, in order to solve this problem, in the past, a heater not shown in the figure and a ring-shaped water-cooling pipe 149 were wound around the outer periphery of the base part 129, and a temperature sensor not shown in the figure (such as a thermistor) was buried in the base part 129, so that the temperature of the base part 129 was maintained at a constant higher temperature (set temperature) based on the signal of the temperature sensor, and the heating of the heater and the cooling of the water-cooling pipe 149 were controlled (hereinafter referred to as TMS. TMS; Temperature Management System).

[0056] Next, the turbo molecular pump 100 configured as described above will be described with respect to the amplifier circuit 150 for controlling the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B. Figure 2 A circuit diagram of the amplifier circuit 150 is shown in FIG.

[0057] Figure 2 In the embodiment, the electromagnet winding 151 constituting the upper radial electromagnet 104 and the like has one end connected to the positive electrode 171a of the power supply 171 via the transistor 161, and the other end connected to the negative electrode 171b of the power supply 171 via the current detection circuit 181 and the transistor 162. Furthermore, the transistors 161 and 162 are so-called power field-effect transistors, each having a diode connected between its source and drain.

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

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

[0060] The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled in five axes and there are ten electromagnets 104, 105, 106A, and 106B in total, the same amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

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

[0062] Amplification control circuit 191 compares the current value detected by current detection circuit 181 (a signal reflecting this current value is referred to as current detection signal 191c) with a predetermined current command value. Based on this comparison result, it determines the pulse width (pulse width times Tp1 and Tp2) generated within one cycle of PWM control, namely, control period Ts. Consequently, amplification control circuit 191 outputs gate drive signals 191a and 191b having the corresponding pulse widths to the gate terminals of transistors 161 and 162.

[0063] Furthermore, when the rotational speed of the rotating body 103 passes through a resonance point during accelerated operation or when external disturbances occur during constant speed operation, high-speed and powerful position control of the rotating body 103 is required. Therefore, in order to enable a rapid increase (or decrease) in the current flowing to the electromagnet winding 151, a high voltage of, for example, approximately 50 V is used as the power supply 171. Furthermore, to stabilize the power supply 171, a capacitor is typically connected between the positive electrode 171a and the negative electrode 171b of the power supply 171 (not shown).

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

[0065] Furthermore, when one of transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is maintained. This flow of flywheel current through amplifier circuit 150 reduces hysteresis losses in amplifier circuit 150, thereby keeping overall circuit power consumption low. Furthermore, by controlling transistors 161 and 162 in this manner, high-frequency noise such as high-pitched waves generated in turbomolecular pump 100 can be reduced. Furthermore, by measuring this flywheel current via current detection circuit 181, the electromagnet current iL flowing through electromagnet winding 151 can be detected.

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

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

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

[0069] The vacuum pump of the first embodiment includes a vacuum pump rotor 200. The vacuum pump rotor 200 is as shown in FIG. Figure 5 As shown, the rotor 103 includes a first rotor blade 201 having a plurality of rotor blades 102 ( 102 a , 102 b , 102 c . . . ), a second rotor blade 202 having a rotating cylindrical portion 102 d , and a heat insulating portion 203 provided between the first rotor blade 201 and the second rotor blade 202 .

[0070] The heat insulator 203 is a component that suppresses heat from the hot second rotor blade 202 into the first rotor blade 201. The heat insulator 203 is an annular or cylindrical spacer. The inner circumference of the heat insulator 203 is connected to the outer circumference of the downstream portion of the first rotor blade 201, while the outer circumference of the heat insulator 203 is connected to the inner circumference of the upstream portion of the second rotor blade 202. The heat insulator 203 is connected to the outer circumference of the portion further downstream than the most downstream rotor blade 102 of the first rotor blade 201. By providing the heat insulator 203, the second rotor blade 202 is not directly connected to the first rotor blade 201, but is indirectly connected to the first rotor blade 201 via the heat insulator 203. Furthermore, as long as the first rotor 201 and the second rotor 202 are not directly connected, the location where the first rotor 201 and the heat insulating portion 203 are connected is not particularly limited, and the location where the second rotor 202 and the heat insulating portion 203 are connected is also not particularly limited.

[0071] The first rotor blade 201 has a cylindrical protrusion 204 that protrudes downstream from the portion connected to the heat insulating portion 203. The inner circumferential surface of the first rotor blade 201, including the protrusion 204, faces the outer circumferential surface of the stator column 122. Therefore, the protrusion 204 exchanges heat with the stator column 122, dissipating heat to the stator column 122.

[0072] The second rotor 202 includes a rotating cylindrical portion 102d and has a cylindrical shape. The outer peripheral surface of the heat insulating portion 203 is connected to the inner peripheral surface of the upstream portion.

[0073] The first member forming the first rotor blade 201 is not particularly limited, but is preferably relatively lightweight, such as an aluminum alloy, to improve the vacuum pump's rotational performance. The second member forming the second rotor blade 202 is not particularly limited, but is preferably highly heat-resistant, such as stainless steel. The first member is lighter than the second member, and the second member has higher heat resistance than the first member.

[0074] The third component forming the heat insulating portion 203 is a low-thermal-conductivity material having a lower thermal conductivity than the first and second materials. Therefore, the heat insulating portion 203 can suppress the flow of heat from the second rotor blade 202, which is the high-temperature portion located downstream, to the first rotor blade 201, which is located downstream and is a low-temperature portion that is not as hot as the high-temperature portion. The third component is not particularly limited, but may be, for example, a ceramic such as zirconium dioxide, a resin material such as polyamide-imide, or a porous material having multiple pores. Porous materials can be formed from, for example, metal materials such as stainless steel and titanium alloys, ceramics, or resin materials. The method for manufacturing the porous material is not particularly limited, and examples include laminating materials using a 3D printer or sintering powder.

[0075] The outer cylinder 127 and the base portion 129 constitute a housing 204. The housing 204 rotatably houses the rotating shaft 113, the first rotor blade 201, and the second rotor blade 202.

[0076] Next, the function of the vacuum pump will be described. When the vacuum pump's rotating shaft 113 is driven by the motor 121 serving as a driving mechanism, the rotating body 103 rotates. This causes the exhaust gas from the chamber to be drawn in through the air intake 101 by the action of the rotating blades 102 and the stationary blades 123.

[0077] Exhaust gas drawn from the intake port 101 is transferred downstream by a turbomolecular pump mechanism formed by the rotating blades 102 and the stationary blades 123 of the first rotor 201. The exhaust gas transferred downstream is guided to a Holweck-type pull pump mechanism formed by the rotating cylindrical portion 102d of the second rotor 202 and the threaded spacer 131, which serves as the stationary cylindrical portion, before being transferred to the exhaust port 133. In this embodiment, the threaded spacer 131 is disposed on the outer periphery of the second rotor 202, with a thread groove 131a formed on its inner circumference. However, conversely, a thread groove may be formed on the outer circumference of the second rotor 202, and a spacer having a cylindrical inner circumference may be disposed around the threaded groove.

[0078] As described above, the vacuum pump of the first embodiment includes a rotating shaft 113 held so as to rotate freely, a driving mechanism (motor 121) for the rotating shaft 113, a first rotating wing 201 formed of a first material, a second rotating wing 202 formed of a second material having higher heat resistance than the first material and arranged downstream of the first rotating wing 201, and a housing 204 in which the rotating shaft 113, the first rotating wing 201, and the second rotating wing 202 are built. The vacuum pump is characterized in that the second rotating wing 202 is arranged on the first rotating wing 201 via a heat insulating portion 203.

[0079] In addition, the vacuum pump rotor 200 includes a first rotor 201 and a second rotor 202. The first rotor 201 is formed of a first material, and the second rotor 202 is formed of a second material having higher heat resistance than the first material, and is arranged downstream of the first rotor 201. The vacuum pump rotor 200 is characterized in that the second rotor 202 is arranged on the first rotor 201 via a heat insulating portion.

[0080] The vacuum pump and vacuum pump rotor 200 constructed as described above have the second rotor 202 located downstream of the first rotor 201, with the second rotor 202 disposed via a heat insulator 203. This reduces the flow of heat into the upstream first rotor 201, even when the downstream second rotor 202 is hot. This prevents overheating of the upstream first rotor 201 and maintains a high temperature for the downstream second rotor 202, thereby preventing the accumulation of reaction products within the vacuum pump. Consequently, decomposition and cleaning of the vacuum pump is unnecessary, or the number of such decomposition and cleaning procedures is reduced, reducing operating time and costs. Furthermore, since overheating of the upstream portion is suppressed, there is no need to limit the flow rate of continuously discharged gas, allowing the gas flow rate to be maintained appropriately.

[0081] The second rotor 202 disposed with respect to the first rotor 201 via the heat insulating portion 203 may be disposed not only directly via the heat insulating portion 203 but also indirectly via the heat insulating portion 203 and a portion or member other than the heat insulating portion 203 .

[0082] Alternatively, the heat insulating portion 203 may be formed of a third material having a lower thermal conductivity than the first and second materials.

[0083] Furthermore, the third material may be a porous material. In this way, the heat insulating portion 203 formed of the porous material having low thermal conductivity can effectively suppress the inflow of heat from the second rotor blade 202 to the first rotor blade 201 .

[0084] Alternatively, the third material may be stainless steel or titanium alloy. In this way, the heat insulating portion 203 formed of stainless steel or titanium alloy having low thermal conductivity can effectively suppress the inflow of heat from the second rotor 202 to the first rotor 201 .

[0085] Furthermore, the third material may be ceramics. In this way, the heat insulating portion 203 formed of ceramics having low thermal conductivity can effectively suppress the inflow of heat from the second rotor blade 202 to the first rotor blade 201 .

[0086] Furthermore, the third material may be a resin material. In this way, the heat insulating portion 203 formed of a resin material having low thermal conductivity can effectively suppress the inflow of heat from the second rotor blade 202 to the first rotor blade 201 .

[0087] Furthermore, the first rotor blade 201 includes rows of multiple rotary blades 102 arranged on its sides. The vacuum pump includes rows of stationary blades 123 arranged between the rows of rotary blades 102. The rows of rotary blades 102 and the rows of stationary blades 123 form a turbomolecular pump mechanism. This allows for efficient exhaust down to relatively low pressures. Furthermore, the heat insulation 203 effectively suppresses heat inflow into the turbomolecular pump mechanism including the first rotor blade 201.

[0088] Furthermore, the second rotor 202 includes at least one rotating cylindrical portion 102d disposed thereon, and the vacuum pump includes at least one stationary cylindrical portion (threaded spacer 131) disposed opposite the outer circumference of the rotating cylindrical portion 102d. The rotating cylindrical portion 102d and the stationary cylindrical portion form a Holweck-type drag pump mechanism. This allows for efficient exhaust even when the pressure near the pump's exhaust port 133 is relatively high. Furthermore, the heat insulation portion 203 reduces heat inflow from the second rotor 202 to the first rotor 201, maintaining the Holweck-type drag pump mechanism, including the second rotor 202, at a high temperature, effectively suppressing the accumulation of reaction products within the drag pump mechanism.

[0089] Furthermore, the first rotor blade 201 is configured so that at least a portion thereof protrudes downstream from the heat insulating portion 203. This increases the surface area (inner circumferential area) of the first rotor blade 201, thereby promoting heat dissipation from the first rotor blade 201 to components disposed inside the first rotor blade 201 (the stator column 122).

[0090] <Second embodiment>

[0091] The vacuum pump of the second embodiment is as follows Figure 6 As shown in FIG. 1 , the structure of the heat insulating portion 302 is different from that of the first embodiment.

[0092] The vacuum pump rotor 300 of the vacuum pump according to the second embodiment includes a first rotor 201, an annular first connecting portion 301 connected to the downstream end of the first rotor 201, a cylindrical heat insulating portion 302 extending upstream from the first connecting portion 301, an annular second connecting portion 303 connected to the upstream end of the heat insulating portion 302, and a cylindrical second rotor 202 extending downstream from the second connecting portion 303. The first connecting portion 301, the heat insulating portion 302, the second connecting portion 303, and the second rotor 202 are integrally formed from the same material (e.g., stainless steel).

[0093] The first connection portion 301 connects the downstream end portion of the first rotor blade 201 and the downstream end portion of the heat insulating portion 302. The first connection portion 301 protrudes radially outward from the outer peripheral surface of the downstream end portion of the first rotor blade 201.

[0094] The second connection portion 303 connects the upstream end portion of the second rotor blade 202 and the upstream end portion of the heat insulating portion 302. The second connection portion 303 protrudes radially inward from the inner peripheral surface of the upstream end portion of the second rotor blade 202.

[0095] The heat insulator 302 is disposed between the outer circumference of the first rotor blade 201 and the inner circumference of the second rotor blade 202, spaced apart from both surfaces. The heat insulator 302 has a heat-insulating structure having a predetermined thickness W1 in the radial direction and a predetermined length L1 in the axial direction. The axial direction refers to the direction along the central axis of rotation of the rotating body 103. The radial direction refers to the direction moving away from or toward the central axis in a cross section perpendicular to the central axis of rotation of the rotating body 103. The thickness W1 is not particularly limited, but is preferably 1 to 10 mm, more preferably 2 to 5 mm, for example, 3 mm. The length L1 is not particularly limited, but is preferably 10 to 50 mm, more preferably 20 to 40 mm, for example, 30 mm. A thinner thickness W1 and a longer length L1 reduce the amount of heat transferred from the heat insulator 302, thereby reducing the influx of heat from the second rotor blade 202 to the first rotor blade 201. The thickness W1 is, for example, smaller than the radial thickness of a portion downstream of the most downstream rotary blade 102 of the first rotary blade 201, and smaller than the radial thickness of a portion upstream of the second rotary blade 202. This reduces the amount of heat transfer from the heat insulating portion 302, and can reduce the inflow of heat from the second rotary blade 202 to the first rotary blade 201.

[0096] As described above, the heat insulating portion 302 of the vacuum pump of the second embodiment has a heat insulating structure having a predetermined length L1 and thickness W1. Thus, the heat insulating portion 302 having the predetermined length L1 and thickness W1 can effectively suppress the flow of heat from the second rotor blade 202 to the first rotor blade 201.

[0097] Furthermore, since the first connecting portion 301 is positioned downstream of the second connecting portion 303, the first rotor blade 201 can be formed longer in the axial direction. This ensures a larger area of ​​facing space between the first rotor blade 201 and the stator post 122, promoting heat dissipation from the first rotor blade 201 to the stator post 122.

[0098] <Third embodiment>

[0099] The vacuum pump of the third embodiment is as follows Figure 7As shown, the present invention is different from the first and second embodiments in that the second rotor 202 is disposed on both the rotation shaft 113 and the first rotor 201 via a heat insulating portion 402 .

[0100] The vacuum pump rotor 400 of the vacuum pump according to the third embodiment includes a first rotor 201, a substantially annular first connecting portion 401 connected to the rotating shaft 113 and the upstream portion of the first rotor 201, a cylindrical heat insulating portion 402 extending downstream from the first connecting portion 401, an annular second connecting portion 403 connected to the downstream end of the heat insulating portion 402, and a cylindrical second rotor 202 extending downstream from the second connecting portion 403. The first connecting portion 401, the heat insulating portion 402, the second connecting portion 403, and the second rotor 202 are integrally formed from the same material (e.g., stainless steel).

[0101] The first connection portion 401 is connected to the outer peripheral surface of the rotating shaft 113 and is axially interposed between the rotating shaft 113 and the first rotor blade 201. The first connection portion 401 extends radially outward from the outer peripheral surface of the rotating shaft 113 and further protrudes downstream.

[0102] The second connection portion 403 connects the upstream end portion of the second rotor blade 202 and the downstream end portion of the heat insulating portion 402. The second connection portion 403 protrudes radially inward from the inner peripheral surface of the upstream end portion of the second rotor blade 202.

[0103] The heat insulator 402 is disposed between the outer circumference of the stator post 122 and the inner circumference of the first rotor blade 201, spaced apart from these surfaces. The heat insulator 402 has a heat-insulating structure having a predetermined radial thickness W2 and a predetermined axial length L2. While the thickness W2 is not particularly limited, it is preferably 1 to 15 mm, more preferably 2 to 8 mm, for example, 5 mm. The length L2 is not particularly limited, but is preferably 20 to 160 mm, more preferably 50 to 120 mm, for example, 80 mm. A thinner thickness W2 and a longer length L2 can reduce heat flow from the second rotor blade 202 to the first rotor blade 201. For example, the thickness W2 is smaller than the radial thickness of the upstream portion of the second rotor blade 202. This further reduces heat flow from the second rotor blade 202 to the first rotor blade 201.

[0104] As described above, the vacuum pump of the third embodiment has the second rotor blade 202 disposed on both sides of the rotating shaft 113 and the first rotor blade 201 via the heat insulating portion 402. Thus, the heat insulating portion 402 effectively prevents heat from flowing from the second rotor blade 202 to the first rotor blade 201. Furthermore, the second rotor blade 202 may be directly disposed on the rotating shaft 113 and the first rotor blade 201 solely via the heat insulating portion 402, or may be indirectly disposed via the heat insulating portion 402 or a portion or component other than the heat insulating portion 402. Furthermore, the second rotor blade 202 may be disposed directly or indirectly via the heat insulating portion 402, rather than directly on the first rotor blade 201, only on the rotating shaft 113.

[0105] Furthermore, the heat insulating portion 402 of the vacuum pump of the third embodiment has a heat insulating structure having a predetermined length L2 and thickness W2. Thus, the heat insulating portion 402 having the predetermined length L2 and thickness W2 can effectively suppress the inflow of heat from the second rotor 202 to the first rotor 201.

[0106] <Fourth embodiment>

[0107] The vacuum pump of the fourth embodiment is as follows Figure 8 As shown in FIG. 1 , the structures of the heat insulating portion 503 and the second rotor 501 are different from those in the first to third embodiments.

[0108] The vacuum pump rotary blade 500 of the vacuum pump of the fourth embodiment includes a first rotary blade 201, an insulating portion 503, and a second rotary blade 501. The insulating portion 503 is connected to the downstream end of the first rotary blade 201 and the upstream end of the second rotary blade 501. The second rotary blade 501 includes two rotating circular plate portions 502 arranged in the axial direction.

[0109] The vacuum pump further includes a stationary circular plate portion 504, which is disposed between the two rotating circular plate portions 502, with the axially facing surfaces of the two rotating circular plate portions 502 facing each other. Multiple vortex-shaped grooves 505 are engraved on both axially facing surfaces of the stationary circular plate portion 504 (the downstream surface and the upstream surface). The vortex direction of the grooves 505 is the direction in which the exhaust gas molecules are transferred toward the exhaust port 133 when they move in the rotation direction of the rotor 103.

[0110] In the fourth embodiment, two rotating circular plate portions 502 and one stationary circular plate portion 504 are provided, but the number of rotating circular plate portions 502 and stationary circular plate portions 504 is not particularly limited. Therefore, for example, one rotating circular plate portion 502 and one stationary circular plate portion 504 may be provided, or two or more rotating circular plate portions 502 and two stationary circular plate portions 504 may be provided.

[0111] The third member forming the heat insulating portion 503 is a low thermal conductivity material having a lower thermal conductivity than the first and second materials. Therefore, the heat insulating portion 503 is a member that suppresses heat from flowing from the second rotor blade 501, which is a high-temperature portion, to the first rotor blade 201, which is a low-temperature portion.

[0112] In the fourth embodiment, the second rotor 501 includes at least one rotating circular plate portion 502 disposed on a side surface of the second rotor 501, and the vacuum pump includes at least one stationary circular plate portion 504 disposed opposite the axially facing surface of the rotating circular plate portion 502. The rotating circular plate portion 502 and the stationary circular plate portion 504 form a Sigbarn-type pull pump mechanism. This allows for efficient exhaust even when the pressure near the pump's exhaust port 133 is relatively high. Furthermore, the heat insulation portion 503 reduces the inflow of heat from the second rotor 501 to the first rotor 201, maintaining the Sigbarn-type pull pump mechanism including the second rotor 501 at a high temperature, effectively suppressing the accumulation of reaction products within the pull pump mechanism.

[0113] In addition, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art can make various changes within the technical concept of the present invention. For example, the high-temperature portion on the downstream side of the vacuum pump can also be formed by combining a Siegbain type traction pump mechanism and a Holwek type traction pump mechanism. For example, the Siegbain type traction pump mechanism can be arranged on the upstream side and the Holwek type traction pump mechanism can be arranged on the downstream side, or vice versa. In addition, in the above-mentioned first to third embodiments, the Holwek type traction pump mechanism is formed by the outer peripheral surface of the rotating cylindrical portion 102d and the inner peripheral surface of the stationary cylindrical portion (threaded spacer 131), but it can also be formed by the inner peripheral surface of the rotating cylindrical portion and the outer peripheral surface of the stationary cylindrical portion.

[0114] Description of Reference Numerals

[0115] 100 turbomolecular pump

[0116] 101 air intake

[0117] 102 rotating blades

[0118] 102d rotating cylinder

[0119] 103 rotating body

[0120] 113 Rotation axis

[0121] 121 motor (drive mechanism)

[0122] 122 stator column

[0123] 123 stationary blades

[0124] 131 threaded spacer (stationary cylinder)

[0125] 133 exhaust port

[0126] Rotary blades for 200, 300, 400, and 500 vacuum pumps

[0127] 201 1st Rotary Wing

[0128] 202, 501 Second Rotor Wing

[0129] 203, 302, 402, 503 insulation parts

[0130] 204 shell

[0131] 502 rotating circular plate part

[0132] 504 stationary circular plate portion

[0133] L1, L2 length of the insulation part

[0134] W1, W2 are the widths of the insulation parts.

Claims

1. A vacuum pump comprising a rotating shaft, a driving mechanism for the rotating shaft, a first rotor, a second rotor, and a housing, wherein the rotating shaft is rotatably held. The first rotor is formed of a first material. The second rotor is formed of a second material having higher heat resistance than the first material and is disposed downstream of the first rotor. The housing houses the rotating shaft, the first rotating blade, and the second rotating blade. The vacuum pump is characterized in that The second rotor is disposed downstream of the most downstream rotor blade of the first rotor via a heat insulating portion.

2. The vacuum pump according to claim 1, wherein The heat insulating portion is formed of a third material having a lower thermal conductivity than the first material and the second material.

3. The vacuum pump according to claim 2, wherein have: a first connecting portion connected to a portion of the first rotor blade that is located downstream of the most downstream rotor blade; The heat insulating portion extends upstream from the first connecting portion; The second connecting portion connects a portion of the heat insulating portion that is located upstream of the portion connected to the first connecting portion to the second rotor.

4. The vacuum pump according to claim 1, wherein The first rotor has a plurality of rows of rotor blades arranged on the side of the first rotor. The vacuum pump has a row of stationary blades disposed between the rows of rotating blades. The row of rotating blades and the row of stationary blades form a turbomolecular pump mechanism.

5. The vacuum pump according to claim 1, wherein The second rotor has at least one rotating cylindrical portion provided thereon. The vacuum pump has at least one stationary cylindrical portion disposed opposite to the outer circumference or inner circumference of the rotating cylindrical portion. The rotating cylindrical portion and the stationary cylindrical portion form a Holweck type traction pump mechanism.

6. The vacuum pump according to claim 1, wherein The second rotor has at least one rotating disc portion provided on a side surface of the second rotor. The vacuum pump includes at least one stationary circular plate portion disposed opposite to the axially facing surface of the rotating circular plate portion, and the rotating circular plate portion and the stationary circular plate portion form a Sigbarn type traction pump mechanism.

7. The vacuum pump according to any one of claims 1 to 6, characterized in that The first rotor is structured so that at least a portion thereof protrudes downstream from the heat insulating portion.

8. A vacuum pump rotor, comprising a first rotor and a second rotor, wherein the first rotor is formed of a first material, and the second rotor is formed of a second material having higher heat resistance than the first material, and is disposed downstream of the first rotor, wherein: The second rotor is disposed downstream of the most downstream rotor blade of the first rotor via a heat insulating portion.

9. The vacuum pump rotor according to claim 8, wherein: have: a first connecting portion connected to a portion of the first rotor blade that is located downstream of the most downstream rotor blade; The heat insulating portion extends upstream from the first connecting portion; The second connecting portion connects a portion of the heat insulating portion that is located upstream of the portion connected to the first connecting portion to the second rotor.

10. A vacuum pump comprising a rotary shaft, a driving mechanism for the rotary shaft, a first rotary blade, a second rotary blade, and a housing, wherein the rotary shaft is rotatably held. The first rotor is formed of a first material. The second rotor is formed of a second material having higher heat resistance than the first material and is disposed downstream of the first rotor. The housing houses the rotating shaft, the first rotating blade, and the second rotating blade. The vacuum pump is characterized in that The second rotor is provided on at least one of the rotation shaft and the first rotor via a cylindrical heat insulating portion extending axially inwardly in the radial direction of the first rotor. The thickness of the heat insulating portion is smaller than the radial thickness of the upstream portion of the second rotor blade. The radially outermost position of the member having the heat insulating portion in contact with at least one of the rotating shaft or the first rotor is located radially inward of the outer peripheral surface of the heat insulating portion.

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