Vacuum pump, rotor and cover

Abstract

To provide a vacuum pump which inhibits contact between a top part of a shaft and a corrosive gas to prevent dust emission from the shaft and has a function for correcting balance of a rotating body.SOLUTION: A vacuum pump according to an embodiment includes: a rotating body including a rotary shaft, and rotary vanes which have through holes, through which a top part of the rotary shaft penetrates, and are fixed by the top part penetrating through the through holes; and a cover part which is fixed to the rotating body so as to cover the top part of the rotary shaft and the through holes. The cover part includes a function for correcting balance of the rotating body and has corrosion resistance against exhaust gas. Providing the cover part inhibits contact between the top part of the shaft and the corrosive gas to prevent dust emission from the shaft. Further, the cover part includes the function for correcting the balance of the rotating body and thus unbalance of the rotating body can be corrected.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a vacuum pump, a rotor, a cover, and a method for manufacturing the rotor. In particular, the present invention relates to a vacuum pump, a rotor, a cover part, and a method for manufacturing a rotor, which have corrosion resistance against exhaust gas while correcting the balance of the rotor by covering the top of the rotor shaft with a cover part fixed to the rotor. [Background technology]

[0002] A vacuum pump has rotors and fixed blades fixed to a rotating shaft, rotates the shaft at high speed, and evacuates the air in a process chamber where a high vacuum is required by the interaction between the rotors and fixed blades rotating at high speed. The gases to be evacuated include corrosive gases such as chlorine and fluorine sulfide, and if the shaft comes into contact with these corrosive gases, there is a risk of dust being generated from the surface of the shaft. For example, one fastening structure for a rotor and a rotor shaft is one in which the top of the shaft (rotor shaft) protrudes from the rotor and a washer for balancing. In response to this, as described in Patent Document 1, corrosion has been prevented by forming a corrosion-preventing coating on the inner and outer peripheral surfaces of the rotor 8 (rotating blades) by electroless plating, or by applying a corrosion-resistant adhesive or paint. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-148389 A

[0004] Patent Document 1 discloses a vacuum pump in which the rotor of the turbo molecular pump is subjected to a corrosion-resistant treatment to protect it from corrosive gases, while the rotor can be balanced for a long period of time. Summary of the Invention [Problem to be solved by the invention]

[0005] In vacuum pumps, the top of the shaft is the first part to come into contact with the corrosive gas taken in from the intake port, and is the most susceptible to the effects of the corrosive gas, so some kind of countermeasure was necessary. In particular, if the top of the shaft comes into contact with the corrosive gas and generates dust, it may flow back from the intake port into the process chamber and adversely affect the quality of the product (wafer). On the other hand, if anti-corrosive treatment is applied to the top of the rotating shaft, it will inevitably affect the balance of the rotating body consisting of the shaft and the rotor fixed to the shaft.

[0006] The present invention aims to provide a vacuum pump, a rotor, a cover part, and a method for manufacturing a rotor that prevents dust generation from the shaft by avoiding contact between the top of the shaft and corrosive gas, and that has a balance correction function for the rotor. [Means for solving the problem]

[0007] The present invention as described in claim 1 provides a vacuum pump including a rotor including a rotatably supported rotor shaft, a rotor having a through hole that passes through a top of the rotor shaft and a rotor blade that is fixed to the rotor shaft by passing the through hole through the top of the rotor shaft, and a cover portion that is fixed to the rotor body so as to cover the top of the rotor shaft and the through hole, wherein the cover portion is a cap portion that covers a top of the rotating shaft, a washer portion for fastening to the rotor blade, and a fitting portion that is provided on the top of the cap portion and fits with a tool for fastening or supporting the rotor, It also has corrosion resistance against exhaust gas. The washer portion is provided with a balance weight screw hole penetrating the washer portion for attaching a balance correction weight for correcting the imbalance of the rotating body. The present invention provides a vacuum pump having a The present invention as set forth in claim 2 provides the vacuum pump as set forth in claim 1, characterized in that the corrosion resistance of the cover portion against exhaust gas is achieved by subjecting the cover portion to a corrosion-resistant surface treatment. Claim 3 In the present invention described, Correction of imbalance of the rotating body is provided in the cover portion Screw hole for balance weight 2. The balance correction is performed by a balance correction weight disposed on the balance correction weight, the balance correction weight being resistant to corrosion caused by exhaust gas. or Claim 2 to A vacuum pump as described above is provided. Claim 4 In the present invention, the balance correction weight is subjected to a surface treatment for corrosion resistance against exhaust gas. 3 The present invention provides a vacuum pump according to the present invention. Claim 5 In the present invention described, a rotor includes a rotatably supported rotor shaft, a through hole that passes through a top of the rotor shaft, and a rotor blade that is fixed to the rotor shaft by passing the through hole through the top of the rotor shaft. The rotor further includes a cover portion that is fixed to the rotor shaft so as to cover the top of the rotor shaft and the through hole. The cover portion is: a cap portion that covers a top of the rotating shaft, a washer portion for fastening to the rotor blade, and a fitting portion that is provided on the top of the cap portion and fits with a tool for fastening or supporting the rotor, It also has corrosion resistance against exhaust gas. The washer portion is provided with a balance weight screw hole penetrating the washer portion for attaching a balance correction weight for correcting the imbalance of the rotating body. The present invention provides a rotating body having a structure comprising: Claim 6 In the present invention described, a cover part is provided which is fixed to a rotor so as to cover the top of the rotor shaft and the through hole of a rotor which includes a rotatably supported rotor shaft and a rotor blade which is fixed to the rotor shaft by passing the through hole through the top of the rotor shaft, a cap portion that covers a top of the rotating shaft, a washer portion for fastening to the rotor blade, and a fitting portion that is provided on the top of the cap portion and fits with a tool for fastening or supporting the rotor, It also has corrosion resistance against exhaust gas. The washer portion is provided with a balance weight screw hole penetrating the washer portion for attaching a balance correction weight for correcting the imbalance of the rotating body. The present invention provides a cover portion having a structure comprising: Effect of the Invention

[0008] According to the present invention, by covering the top of the shaft and the through hole in the rotor through which the shaft passes with the cover portion, it is possible to prevent contact between the corrosive gas and the shaft, particularly the top of the shaft, and the balance correction function provided in the cover portion can be used to correct the balance of the rotor. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration example of a turbomolecular pump according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a circuit diagram of an amplifier circuit used in an embodiment of the present invention. [Diagram 3] 5 is a time chart showing control when a current command value is smaller than a detection value in the embodiment of the present invention. [Figure 4] 5 is a time chart showing control when a current command value is larger than a detection value in the embodiment of the present invention. [Diagram 5] 1 is a diagram showing a schematic configuration example including a cover portion of a vacuum pump according to an embodiment of the present invention; [Figure 6] FIG. 1 is a diagram illustrating an example of a schematic configuration of a rotating body according to an embodiment of the present invention. [Figure 7] 3A and 3B are diagrams illustrating an example of a schematic configuration of a cover portion according to an embodiment of the present invention. [Figure 8] FIG. 8 is a perspective view of the cover portion shown in FIG. [Figure 9] 11A to 11C are views for explaining a rotating body assembling step (before the armature disk is fixed) in the embodiment. [Figure 10] 11A to 11C are views for explaining a rotating body assembling step (after the armature disk is fixed) in the embodiment. [Figure 11] 6A to 6C are diagrams for explaining a rotating body assembling step (shaft fastening) in the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (i) Overview of the embodiment A vacuum pump according to an embodiment of the present invention comprises a rotor having a rotating shaft, a rotor blade having a through hole passing through the top of the rotating shaft and fixed to the top by passing through the through hole, and a cover portion fixed to the rotor so as to cover the top of the rotating shaft and the through hole, the cover portion having a balance correction function for correcting imbalance of the rotor and having corrosion resistance against exhaust gas.

[0011] In this embodiment, by providing the cover, it is possible to prevent the top of the shaft (top of the rotor shaft) from coming into contact with corrosive gas and to prevent dust from being generated from the shaft. In addition, since the cover has a function of correcting the balance of the rotor, the imbalance of the rotor can be corrected even if the cover is provided on the top of the shaft.

[0012] (ii) Details of the embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to FIGS. The cover portion 500, which is a characteristic feature of this embodiment, will be described in detail with reference to FIGS.

[0013] A longitudinal cross-sectional view of this turbomolecular pump (vacuum pump) 100 is shown in Fig. 1. In Fig. 1, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer tube 127. Inside the outer tube 127, a rotor 103 is provided, the rotor 103 having a plurality of rotors 102 (102a, 102b, 102c, ...) which are turbine blades for sucking in and exhausting gas, formed radially on its periphery in multiple stages. A rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is levitated and supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing. The rotor 103 is generally made of a metal such as aluminum or an aluminum alloy.

[0014] The upper radial electromagnets 104 are arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to each of the upper radial electromagnets 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on the change in inductance of the conductive windings that changes according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send the detected displacement to the control device 200.

[0015] In this control device 200, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on a position signal detected by the upper radial sensor 107, and an amplifier circuit 150 (described later) shown in Figure 2 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

[0016] The rotor shaft 113 is made of a material with high magnetic permeability (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. The lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107, and adjust the lower radial position of the rotor shaft 113 in the same manner as the upper radial position.

[0017] Furthermore, axial electromagnets 106A and 106B are arranged above and below a circular metal disk 111 provided at the bottom of rotor shaft 113. Metal disk 111 is made of a high magnetic permeability material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and an axial position signal is sent to control device 200.

[0018] In the control device 200, a compensation circuit having, for example, a PID adjustment function generates an excitation control command signal for each of the axial electromagnets 106A and 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnets 106A and 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0019] In this way, the control device 200 appropriately adjusts the magnetic force that the axial electromagnets 106A, 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in a non-contact manner in space. The amplifier circuit 150 that controls the excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A, 106B will be described later.

[0020] Meanwhile, motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround rotor shaft 113. Each magnetic pole is controlled by control device 200 so as to rotate rotor shaft 113 via electromagnetic force acting between the magnetic pole and rotor shaft 113. Also, motor 121 incorporates a rotation speed sensor such as a Hall element, resolver, or encoder (not shown), and the rotation speed of rotor shaft 113 is detected by a detection signal from this rotation speed sensor.

[0021] Furthermore, for example, a phase sensor (not shown) is attached near the lower radial sensor 108 to detect the phase of rotation of the rotor shaft 113. The control device 200 detects the position of the magnetic poles using the detection signals of both this phase sensor and the rotation speed sensor.

[0022] A plurality of fixed blades 123 (123a, 123b, 123c...) are arranged with a small gap between the rotor blades 102 (102a, 102b, 102c...). The rotor blades 102 (102a, 102b, 102c...) are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward through collision. The fixed blades 123 (123a, 123b, 123c...) are made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components.

[0023] Similarly, the fixed blades 123 are formed at an inclination at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged alternately with the stages of the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral ends of the fixed blades 123 are supported in a state where they are inserted between a plurality of stacked stages of fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0024] The fixed wing spacer 125 is a ring-shaped member and is made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a small gap therebetween. A base portion 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129 and communicates with the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) side and is transferred to the base portion 129 is sent to the exhaust port 133.

[0025] Furthermore, depending on the application of the turbo molecular pump 100, a threaded spacer 131 is disposed between the lower part of the fixed vane spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has a plurality of helical thread grooves 131a engraved on its inner peripheral surface. The helical direction of the thread groove 131a is the direction in which, when the molecules of the exhaust gas move in the rotation direction of the rotor 103, the molecules are transferred toward the exhaust port 133. A cylindrical part 102d hangs down from the lowest part of the rotor 103, which is connected to the rotor vanes 102 (102a, 102b, 102c, etc.). The outer peripheral surface of this cylindrical part 102d is cylindrical and protrudes toward the inner peripheral surface of the threaded spacer 131, and is adjacent to the inner peripheral surface of the threaded spacer 131 with a predetermined gap therebetween. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blade 123 is sent to the base portion 129 while being guided by the thread groove 131a.

[0026] The base portion 129 is a disk-shaped member that constitutes the base of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, stainless steel, etc. The base portion 129 physically holds the turbomolecular pump 100 and also functions as a heat conduction path, so it is desirable to use a metal that has rigidity and high thermal conductivity, such as iron, aluminum, or copper.

[0027] In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the exhaust gas is sucked from the chamber through the intake port 101 by the action of the rotor 102 and the fixed blade 123. The rotation speed of the rotor 102 is usually 20,000 rpm to 90,000 rpm, and the peripheral speed at the tip of the rotor 102 reaches 200 m / s to 400 m / s. The exhaust gas sucked through the intake port 101 passes between the rotor 102 and the fixed blade 123 and is transferred to the base part 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121, and the like, but this heat is transferred to the fixed blade 123 side by radiation or conduction by gas molecules of the exhaust gas, and the like.

[0028] The fixed blade spacers 125 are joined to each other at their outer peripheries, and transmit heat received by the fixed blades 123 from the rotor blades 102, frictional heat generated when exhaust gas comes into contact with the fixed blades 123, and the like to the outside.

[0029] In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotor 103, and the thread groove 131a is formed on the inner periphery of the threaded spacer 131. However, there are also cases where the thread groove is formed on the outer periphery of the cylindrical portion 102d, and a spacer having a cylindrical inner periphery is disposed around the outer periphery of the cylindrical portion 102d.

[0030] Depending on the application of the turbomolecular pump 100, in order to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section, which is composed of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., the electrical equipment section may be covered all around with a stator column 122, and the inside of this stator column 122 may be kept at a predetermined pressure by a purge gas.

[0031] In this case, piping (not shown) is provided in the base portion 129, and purge gas is introduced through this piping. The introduced purge gas is sent to the exhaust port 133 through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102.

[0032] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that are individually adjusted and identified as a model. In order to store these control parameters, the turbomolecular pump 100 has an electronic circuit section 141 in its main body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown) near the center of a base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom cover 145.

[0033] In the semiconductor manufacturing process, some process gases introduced into the chamber have the property of becoming solid when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the turbo molecular pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. If the pressure of the process gas becomes higher than a predetermined value or the temperature falls below a predetermined value while the process gas is being transferred from the intake port 101 to the exhaust port 133, the process gas becomes solid and adheres to and accumulates inside the turbo molecular pump 100.

[0034] For example, when SiCl4 is used as the process gas in an Al etching device, low vacuum (760[torr]~10 -2It can be seen from the vapor pressure curve that at a vapor pressure of 100 MPa (100 [torr]) and low temperature (approximately 20 [°C]), solid products (e.g., AlCl3) precipitate and adhere to and accumulate inside the turbomolecular pump 100. As a result, when precipitates of the process gas accumulate inside the turbomolecular pump 100, the deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The above-mentioned products are prone to solidification and adhesion in high-pressure areas near the exhaust port 133 and near the threaded spacer 131.

[0035] Therefore, in order to solve this problem, in the past, a heater (not shown) or a circular water-cooled tube 149 was wrapped around the outer periphery of the base portion 129, and a temperature sensor (e.g., a thermistor) (not shown) was embedded in the base portion 129, and the heating of the heater and the cooling by the water-cooled tube 149 were controlled based on the signal from this temperature sensor to keep the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; Temperature Management System).

[0036] Next, regarding the turbo molecular pump 100 configured as described above, an amplifier circuit 150 that controls excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B will be described. A circuit diagram of this amplifier circuit 150 is shown in FIG.

[0037] 2, one end of an electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to a positive electrode 171a of a power source 171 via a transistor 161, and the other end is connected to a negative electrode 171b of the power source 171 via a current detection circuit 181 and a transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

[0038] At this time, the transistor 161 has a cathode terminal 161a of the diode connected to the positive electrode 171a, and an anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has a cathode terminal 162a of the diode connected to the current detection circuit 181, and an anode terminal 162b connected to the negative electrode 171b.

[0039] On the other hand, the current regeneration diode 165 has its cathode terminal 165a connected to one end of the electromagnet winding 151 and its anode terminal 165b connected to the negative electrode 171b. Similarly, the current regeneration diode 166 has its cathode terminal 166a connected to the positive electrode 171a and its anode terminal 166b connected to the other end of the electromagnet winding 151 via a current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall sensor type current sensor or an electric resistance element.

[0040] The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, when the magnetic bearing is controlled by five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0041] Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) (not shown) of the control device 200, and this amplifier control circuit 191 switches the transistors 161 and 162 on / off.

[0042] The amplifier control circuit 191 is adapted to compare the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Then, based on the result of this comparison, the magnitude of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control, is determined. As a result, gate drive signals 191a, 191b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of the transistors 161, 162.

[0043] In addition, when the rotor 103 passes through a resonance point during an accelerating operation of the rotation speed, or when a disturbance occurs during a constant speed operation, it is necessary to control the position of the rotor 103 at high speed and with a strong force. For this reason, a high voltage of, for example, about 50 V is used as the power supply 171 so that the current flowing through the electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between the positive pole 171a and the negative pole 171b of the power supply 171 to stabilize the power supply 171.

[0044] In this configuration, when both transistors 161, 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.

[0045] Moreover, when one of the transistors 161, 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By passing a flywheel current through the amplifier circuit 150 in this manner, the hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Furthermore, by controlling the transistors 161, 162 in this manner, high-frequency noise such as harmonics generated in the turbo molecular pump 100 can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.

[0046] That is, when the detected current value is smaller than the current command value, both of the transistors 161 and 162 are turned on for a time period corresponding to the pulse width time Tp1 only once in a control cycle Ts (e.g., 100 μs) as shown in Fig. 3. Therefore, the electromagnet current iL during this period increases toward a current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.

[0047] On the other hand, when the detected current value is larger than the current command value, both of the transistors 161 and 162 are turned off for a time period corresponding to the pulse width time Tp2 only once during the control cycle Ts, as shown in Fig. 4. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from the negative pole 171b to the positive pole 171a via the diodes 165 and 166.

[0048] In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, a flywheel current is maintained in the amplifier circuit 150 during this period.

[0049] Fig. 5 is a diagram showing a schematic configuration example of a vacuum pump (turbo molecular pump) according to this embodiment, including a cover portion 500. Fig. 6 is a diagram showing a schematic configuration example of a rotating body according to this embodiment. 5, cover part 500 is installed so as to cover rotor shaft top 210 of rotor shaft 113. Installing this cover part 500 makes it possible to completely cover rotor shaft top 210 and through holes 220 opened in rotor blades 102 (102a, 102b, 102c, etc.) to allow rotor shaft top 210 to pass therethrough. Cover part 500 is fixed to rotor blades 102 with fastening bolts 560. Since the cover portion 500 comes into contact with the process gas, it is preferable to subject the cover portion 500 to a corrosion-resistant surface treatment. This cover portion 500 can prevent the process gas taken in from the intake port 101 from coming into contact with the rotor shaft top portion 210, and can also prevent the process gas from passing through the through hole 220 and entering further inside.

[0050] FIG. 7 is a diagram showing a schematic configuration example of a cover section 500 according to an embodiment of the present invention, and FIG. 8 is a perspective view of the cover section 500 shown in FIG. Cover portion 500 is shaped like a top hat to cover rotor shaft top portion 210 and through hole 220, and is formed from a cap portion 510 and a washer portion 520. Since cover portion 500 also has a balancing function, it is desirable that it be as concentric as possible with rotor shaft 113 and be a perfect circle. The cap portion 510 is shaped to mate with the shape of the rotor top 210 to cover the rotor top 210 . Furthermore, the washer portion 520 not only fixes the cover portion 500 and the rotor 102, but also fastens the rotor 102 and the rotor shaft 113, and is provided with a plurality (eight in this embodiment) of bolt through holes 530. The number of bolt through holes 530 is not limited to eight, and may be other numbers such as two, four, or six. This bolt through hole 530 penetrates the washer portion 520, and when the cover portion 500 is installed, a fastening bolt 560 is passed through to fix (fasten) the cover portion to the rotor 102 and the rotor shaft 113 (threads are cut on the rotor shaft 113 side). As a method for fixing the cover portion 500 and the rotor 102, a screw may be cut on the rotor 102 side. Since the fastening bolt 560 comes into contact with the process gas, it is desirable to subject it to a corrosion-resistant surface treatment or to use a corrosion-resistant material.

[0051] The washer portion 520 is further provided with balance weight screw holes 540. In the embodiment shown in the figure, 24 balance weight screw holes 540 are provided, but this number can be set appropriately. The balance weight screw hole 540 is internally threaded for attaching a balance weight screw 570. Fig. 7 shows the balance weight screw hole 540 with the balance weight screw 570 attached thereto. By fitting a balance weight screw 570 into this balance weight screw hole 540 while adjusting the balance, the balance of the rotating body (the rotor blades 102 and the rotor shaft 113) rotating at high speed can be corrected. In this embodiment, the imbalance can be corrected with the cover portion 500 fixed.

[0052] Since the balance weight screw 570 comes into contact with the process gas, it is preferable that the balance weight screw 570 is corrosion resistant, for example, by being subjected to a corrosion resistant surface treatment. In this manner, the cover portion 500 has the function of preventing contact between the rotor shaft top portion 210 and the process gas, and of correcting the balance of the rotating body when the cover portion is attached.

[0053] A fitting portion 550 is provided at the top of the cover portion 500. This fitting portion 550 is shaped to fit with a predetermined tool in the process of assembling the rotor 102, and by fitting with the tool, it can play a role in supporting and fixing the rotor 102 via the cover portion 500, and plays a role in the rotor assembly process described below.

[0054] The material of the cover part 500 is desirably more corrosion resistant than the rotor shaft 113 (rotor shaft top part 210). For example, the material of the cover part 500 may be SUS316, which is highly corrosion resistant among stainless steels.

[0055] Next, the rotating body assembling process in this embodiment will be described. FIG. 9 is a view for explaining the rotating body assembling process in this embodiment (before the armature disk is fixed), FIG. 10 is a view for explaining the rotating body assembling process in this embodiment (after the armature disk is fixed), and FIG. 11 is a view for explaining the rotating body assembling process in this embodiment (shaft fastening).

[0056] As shown in FIG. 9, before the armature disk 310 is fixed, the washer 300, the armature disk 310 and the nut 320 are assembled in this order. The washer 300 is provided for alignment purposes and also serves the purpose of preventing magnetic flux from the armature disk 310 from wandering around. The armature disk 310 is made of a magnetic material and is a disk for exerting an attractive force by an electromagnet. A nut 320 tightens and secures the armature disc 310 .

[0057] 10, the nut 320 is tightened with a tool 700 to fix the washer 300 and the armature disk 310. At this time, in order to prevent the rotor shaft 113 from rotating and making it impossible to tighten the nut, the cover part 500 is fixed with a tool 600. This tool 600 is shaped to fit with a fitting part 550 provided on the top of the cover part 500. Since the cover portion 500 is fixed (fastened) to the rotor 102 and the rotor shaft 113, by fixing the fitting portion 550 provided on the top of the cover portion 500 with the tool 600, the nut 320 can be easily tightened without the rotor 102 and the rotor shaft 113 rotating.

[0058] Next, although the order of steps may vary, the process for assembling the rotor (fastening the shaft) will be described. 11, the fastening bolt 560 is fastened using a tool 800. At this time, too, the cover portion 500 is fixed with a tool 600 to prevent the rotor shaft 113 from rotating and making it impossible to fasten the bolt. In this way, the cover portion 500 can be easily and reliably fastened to the rotor blades 102 and the rotor shaft 113.

[0059] The embodiments and modifications of the present invention may be combined with each other as necessary.

[0060] Furthermore, the present invention can be modified in various ways without departing from the spirit of the present invention, and it goes without saying that the present invention covers such modifications. [Explanation of symbols]

[0061] 100 Turbo molecular pump (vacuum pump) 101 Air intake 102 Rotor 102d Cylindrical section 103 Rotating Body 113 Rotor shaft 123 Fixed wing 125 Fixed wing spacer 127 Outer cylinder 129 Base 131 Threaded spacer 131a Thread groove 133 Exhaust port 200 Control device 210 Rotor shaft top 220 Through hole 300 Washer 310 Armature disc 320 Nut 500 Cover 510 Cap section 520 Washer part 530 Bolt Through Hole 540 Screw hole for balance weight 550 Fitting part 560 Fastening bolt 570 Balance weight screw 600, 700, 800 tools

Claims

1. a rotor including a rotatably supported rotating shaft and a rotor blade having a through hole penetrating a top of the rotating shaft and fixed to the top by penetrating the through hole; A vacuum pump including a cover portion fixed to the rotor so as to cover a top portion of the rotary shaft and the through hole, the cover portion includes a cap portion that covers a top portion of the rotating shaft, a washer portion for fixing to the rotor blade, and a fitting portion that is provided on the top portion of the cap portion and fits with a tool for fixing or supporting the rotor, and has corrosion resistance against exhaust gas; a screw hole for a balance weight is provided through the washer portion for attaching a balance correction weight for correcting unbalance of the rotating body, the screw hole being provided through the washer portion.

2. 2. The vacuum pump according to claim 1, wherein the corrosion resistance of said cover portion against exhaust gas is achieved by subjecting said cover portion to a corrosion-resistant surface treatment.

3. A vacuum pump as described in claim 1 or claim 2, characterized in that the unbalance of the rotating body is corrected by a balance correction weight placed in a balance weight screw hole provided in the cover portion, and the balance correction weight has corrosion resistance against exhaust gas.

4. 4. The vacuum pump according to claim 3, wherein the balance correction weight is subjected to a surface treatment for resistance to corrosion caused by exhaust gas.

5. A rotor including a rotatably supported rotating shaft, and a rotor blade having a through hole penetrating a top of the rotating shaft and fixed to the top by penetrating the through hole, A cover portion is fixed to the rotor so as to cover a top portion of the rotating shaft and the through hole, the cover portion includes a cap portion that covers a top portion of the rotating shaft, a washer portion for fixing to the rotor blade, and a fitting portion that is provided on the top portion of the cap portion and fits with a tool for fixing or supporting the rotor, and has corrosion resistance against exhaust gas; A rotating body, wherein the washer portion has a threaded hole for a balance weight penetrating the washer portion for attaching a balance correction weight for correcting imbalance of the rotating body.

6. A cover part is fixed to a rotor so as to cover the top of the rotor shaft and the through hole of a rotor including a rotatably supported rotor shaft and a rotor blade having a through hole penetrating a top of the rotor shaft and fixed to the rotor blade by penetrating the through hole to the top of the rotor shaft, a cap portion that covers a top of the rotating shaft, a washer portion for fixing to the rotor blade, and a fitting portion that is provided on the top of the cap portion and fits with a tool for fixing or supporting the rotor, and the rotating body has corrosion resistance against exhaust gas; A cover portion characterized in that a balance weight screw hole for attaching a balance correction weight for correcting imbalance of the rotating body is provided through the washer portion.

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