Vacuum pump, rotating body, cover portion, and manufacturing method for rotating body

Abstract

In a vacuum pump (100) related to the present application, there are provided: a rotating body (103) having a rotating shaft (113) and a rotating blade (102), the rotating blade (102) having a through hole (220) for the top of the rotating shaft (113) to pass through, and the top being fixed with the through hole (220) passing through; and a cover part (500) fixed to the rotating body (103) in a manner of covering the top of the rotating shaft (113) and the through hole (220). The cover part (500) has a balance correction function of the rotating body (103) and has corrosion resistance to exhaust gas. By providing the cover part (500), the contact of the top of the shaft with corrosive gas can be avoided, and dusting from the shaft can be prevented; since the cover part (500) has the balance correction function of the rotating body, the imbalance of the rotating body (103) can be corrected.

Description

Technical Field

[0001] This invention relates to a vacuum pump, a rotating body, a cover, and a method for manufacturing the rotating body.

[0002] In detail, the invention relates to a method of manufacturing a vacuum pump, a rotating body, a cover, and a rotating body that provides corrosion resistance to exhaust gases while performing balance correction of the rotating body by covering the top of the shaft of the rotating body with a cover fixed to the rotating body. Background Technology

[0003] A vacuum pump has rotating blades and fixed blades fixed to a rotating shaft (shaft). The shaft rotates at high speed, and the interaction between the high-speed rotating blades and the fixed blades allows for the vacuum removal of air from a process chamber requiring high vacuum. The discharged gas may contain corrosive gases such as chlorine or fluorine sulfide. If these corrosive gases come into contact with, for example, the shaft, dust may be generated from the shaft surface.

[0004] For example, as a fastening structure between the rotating blades and the rotating shaft (shaft), there is a structure in which the top of the shaft (rotor shaft) protrudes from the rotating blades and the balancing washer.

[0005] In contrast, as described in Patent Document 1, corrosion is prevented by forming an anti-corrosion film on the inner and outer circumferential surfaces of the rotor 8 (rotating blade) using an electroless plating layer, or by applying a corrosion-resistant adhesive or coating.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2003-148389

[0009] Patent document 1 discloses a vacuum pump that, by treating the rotating body of a turbomolecular pump with corrosion resistance, can maintain the balance of the rotating body for a long period of time while being protected against corrosive gases. Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] Furthermore, in a vacuum pump, the top of the shaft is the first part to come into contact with the corrosive gases drawn in from the suction port, making it most susceptible to their effects and requiring countermeasures. In particular, if dust is generated due to contact between the top of the shaft and the corrosive gases, it may flow back from the suction port into the process chamber, adversely affecting the quality of the product (wafer).

[0012] On the other hand, if the top of the rotating shaft is treated with corrosion resistance, it will inevitably affect the balance of the rotating body consisting of the shaft and the rotating blades fixed on the shaft.

[0013] The purpose of this invention is to provide a vacuum pump, a rotating body, a cover, and a method for manufacturing the rotating body, which prevents dust from rising from the shaft by avoiding contact between the top of the shaft and corrosive gas, and has a balance correction function for the rotating body.

[0014] Methods for solving technical problems

[0015] In the invention described in technical solution 1 of this application, a vacuum pump is provided, comprising: a rotating body having a rotating shaft and rotating blades rotatably supported thereon, the rotating blades having a through hole through which the top of the aforementioned rotating shaft passes, thereby fixing the aforementioned top through the through hole; and a cover portion fixed to the aforementioned rotating body in such a way as to cover the top of the aforementioned rotating shaft and the aforementioned through hole; characterized in that the aforementioned cover portion has a balancing function for correcting the imbalance of the aforementioned rotating body, and is corrosion resistant to the discharged gas.

[0016] In the invention described in technical solution 2 of this application, a vacuum pump as described in technical solution 1 is provided, characterized in that the corrosion resistance of the aforementioned cover to the discharged gas is achieved by performing a corrosion-resistant surface treatment.

[0017] In the invention of this application described in technical solution 3, a vacuum pump described in technical solution 1 or technical solution 2 is provided, characterized in that the aforementioned cover has a portion that engages with a tool for fixing or supporting the aforementioned rotating body.

[0018] In the invention of this application described in technical solution 4, a vacuum pump described in any one of technical solutions 1 to 3 is provided, characterized in that the aforementioned balance correction function is performed by a balance correction weight disposed in the recess of the aforementioned cover, the balance correction weight being corrosion resistant to the discharged gas.

[0019] In the invention of this application described in technical solution 5, a vacuum pump described in technical solution 4 is provided, characterized in that the aforementioned balance correction weight is subjected to a surface treatment that is corrosion resistant to the exhaust gas.

[0020] In the invention described in technical solution 6 of this application, a rotating body is provided, comprising a rotating shaft and rotating blades rotatably supported, wherein the rotating blades have a through hole through which the top of the aforementioned rotating shaft passes, thereby fixing the aforementioned top through the through hole. The invention is characterized by further comprising a cover portion fixed to the aforementioned rotating body in such a way as to cover the top of the aforementioned rotating shaft and the aforementioned through hole; the aforementioned cover portion has a balancing function for correcting the imbalance of the aforementioned rotating body and is corrosion resistant to exhaust gases.

[0021] In the invention described in technical solution 7 of this application, a cover is provided to fix the top of the rotating shaft and the through hole of the rotating body to the aforementioned rotating body. The rotating body has the aforementioned rotating shaft and rotating blades that are rotatably supported. The rotating blades have the aforementioned through hole through which the top of the aforementioned rotating shaft passes, so that the aforementioned top passes through the through hole and is fixed. The invention is characterized by having a balance correction function for correcting the imbalance of the aforementioned rotating body and being corrosion resistant to the exhaust gas.

[0022] In the invention described in technical solution 8 of this application, a method for manufacturing a rotating body is provided. The rotating body has a rotating shaft and rotating blades that are rotatably supported. The rotating blades have a through hole through which the top of the aforementioned rotating shaft passes, and the aforementioned top passes through the through hole and is fixed. The method is characterized in that a cover that is corrosion resistant to exhaust gas is fixed to the aforementioned rotating body in such a way that it covers the top of the aforementioned rotating shaft and the aforementioned through hole, and the imbalance of the aforementioned rotating body is corrected while the aforementioned cover is fixed.

[0023] Invention Effects

[0024] According to the present invention, by covering the top of the shaft and the through hole provided in the rotating blade through which the shaft passes by with a cover, corrosive gases can be prevented from contacting the shaft, especially the top of the shaft, and the balance correction function provided by the cover can correct the balance of the rotating body. Attached Figure Description

[0025] Figure 1 This is a diagram illustrating a schematic structural example of a turbomolecular pump according to an embodiment of the present invention.

[0026] Figure 2 This is a circuit diagram showing the amplifier circuit used in an embodiment of the present invention.

[0027] Figure 3 This is a timing diagram illustrating the control when the current command value is smaller than the detection value in an embodiment of the present invention.

[0028] Figure 4 This is a timing diagram illustrating the control when the current command value is greater than the detection value in an embodiment of the present invention.

[0029] Figure 5 This is a diagram illustrating a schematic structural example of a vacuum pump, including a cover, according to an embodiment of the present invention.

[0030] Figure 6 This is a diagram illustrating a schematic structural example of a rotating body according to an embodiment of the present invention.

[0031] Figure 7 This is a diagram showing a schematic structural example of the cover portion according to an embodiment of the present invention.

[0032] Figure 8 yes Figure 7 The three-dimensional view of the cover shown.

[0033] Figure 9 This diagram illustrates the assembly process of the rotating body (before the armature disk is fixed) in this embodiment.

[0034] Figure 10 This diagram illustrates the assembly process of the rotating body (after the armature disk is fixed) in this embodiment.

[0035] Figure 11 This diagram illustrates the assembly process (shaft fastening) of the rotating body in this embodiment. Detailed Implementation

[0036] (i) Overview of the implementation method

[0037] In a vacuum pump according to an embodiment of the present invention, there is: a rotating body having a rotating shaft and rotating blades, the rotating blades having a through hole through which the top of the rotating shaft passes, the top passing through the through hole and being fixed; and a cover fixed to the rotating body in such a way as to cover the top of the rotating shaft and the through hole; the cover has a balancing function for correcting imbalances in the rotating body and is corrosion resistant to the exhaust gas.

[0038] In this embodiment, by providing a cover, contact between the top of the shaft (top of the rotor shaft) and corrosive gases can be avoided, thus preventing dust from rising from the shaft. Furthermore, since the cover has a balance correction function for the rotating body, even if the cover is provided on the top of the shaft, the imbalance of the rotating body can be corrected.

[0039] (ii) Details of the implementation method

[0040] The following is for reference Figures 1 to 11 Preferred embodiments of the present invention will be described in detail.

[0041] Furthermore, for the cover portion 500, which is a characteristic part of this embodiment, using Figures 5 to 8 A detailed explanation will be provided.

[0042] exist Figure 1 The image shows a longitudinal sectional view of the turbomolecular pump (vacuum pump) 100. Figure 1In this turbomolecular pump 100, an intake port 101 is formed at the upper end of a cylindrical outer cylinder 127. Furthermore, a rotating body 103 is provided inside the outer cylinder 127. This rotating body 103 has multiple rotating blades 102 (102a, 102b, 102c…) arranged radially and in multiple stages around its periphery, serving as turbine blades for drawing in and expelling gas. A rotor shaft 113 is mounted at the center of this rotating body 103. This rotor shaft 113 is suspended in the air and its position is controlled, for example, by a 5-axis controlled magnetic bearing. The rotating body 103 is generally made of a metal such as aluminum or an aluminum alloy.

[0043] Four upper radial electromagnets 104 are arranged in pairs along the X and Y axes. Approaching and corresponding to each upper radial electromagnet 104, four upper radial sensors 107 are provided. The upper radial sensors 107 use, for example, inductive sensors with conductive coils or eddy current sensors, to detect the position of the rotor shaft 113 based on changes in the inductance of the conductive coil corresponding to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send this displacement to the control device 200.

[0044] In the control device 200, for example, a compensation circuit with PID regulation function generates an excitation control command signal for the upper radial electromagnet 104 based on the position signal detected by the upper radial sensor 107. Figure 2 The amplifier circuit 150 shown (described later) controls the excitation of the upper radial electromagnet 104 based on the excitation control command signal, thereby adjusting the radial position of the upper side of the rotor shaft 113.

[0045] Furthermore, the rotor shaft 113 is formed of a material with high magnetic permeability (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. This adjustment is performed independently in the X-axis and Y-axis directions respectively. In addition, the lower radial electromagnet 105 and the lower radial sensor 108 are configured in the same way as the upper radial electromagnet 104 and the upper radial sensor 107, and the lower radial position of the rotor shaft 113 is adjusted in the same way as the upper radial position.

[0046] Furthermore, axial electromagnets 106A and 106B are arranged vertically above and below a circular metal disc 111 mounted on the lower part of the rotor shaft 113. The metal disc 111 is made of a material with high magnetic permeability, such as iron. An axial sensor 109 is provided to detect the axial displacement of the rotor shaft 113, and is configured to send its axial position signal to the control device 200.

[0047] Furthermore, in the control device 200, for example, a compensation circuit with PID regulation function generates excitation control command signals for axial electromagnets 106A and 106B based on the axial position signal detected by the axial sensor 109. The amplifier circuit 150 performs excitation control on axial electromagnets 106A and 106B based on these excitation control command signals, so that axial electromagnet 106A uses magnetic force to attract metal disk 111 upward, and axial electromagnet 106B attracts metal disk 111 downward, thereby adjusting the axial position of rotor shaft 113.

[0048] In this way, the control device 200 appropriately adjusts the magnetic force exerted by the axial electromagnets 106A and 106B on the metal disk 111, so that the rotor shaft 113 is magnetically levitated in the axial direction and held in space without contact. Furthermore, the amplifier circuit 150 that controls the excitation of these upper radial electromagnets 104, lower radial electromagnets 105, and axial electromagnets 106A and 106B will be described later.

[0049] On the other hand, the motor 121 has a plurality of magnetic poles arranged circumferentially to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 to drive the rotor shaft 113 to rotate via an electromagnetic force acting between the magnetic pole and the rotor shaft 113. In addition, a rotational speed sensor (not shown), such as a Hall element, a rotary transformer, or an encoder, is installed in the motor 121 to detect the rotational speed of the rotor shaft 113 based on the detection signal from the rotational speed sensor.

[0050] Furthermore, for example, a phase sensor (not shown) is installed near the lower radial sensor 108 to detect the phase of rotation of the rotor shaft 113. In the control device 200, the detection signals from both the phase sensor and the rotational speed sensor are used simultaneously to detect the position of the magnetic poles.

[0051] Multiple fixed blades 123 (123a, 123b, 123c...) are arranged with slight gaps between them and the rotating blades 102 (102a, 102b, 102c...). The rotating blades 102 (102a, 102b, 102c...) are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to move the molecules of the exhaust gas downward by means of collision. The fixed blades 123 (123a, 123b, 123c...) are made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components.

[0052] Furthermore, the fixed blade 123 is also formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and is arranged offset from the layers of the rotating blade 102 towards the inner side of the outer cylinder 127. Moreover, the outer peripheral end of the fixed blade 123 is supported in a state of being inserted between multiple stacked fixed blade spacers 125 (125a, 125b, 125c...).

[0053] The fixed blade spacer 125 is an annular component, made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed blade spacer 125 with a slight gap. A base portion 129 is provided at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129, communicating with the outside. Exhaust gas entering the intake port 101 from the chamber (vacuum chamber) side and being transferred to the base portion 129 is conveyed to the exhaust port 133.

[0054] Furthermore, according to the application of the turbomolecular pump 100, a threaded spacer 131 is provided between the lower part of the fixed blade spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical component made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has multiple helical threaded grooves 131a engraved on its inner circumferential surface. The helical direction of the threaded grooves 131a is the direction in which the molecules of the exhaust gas are moved toward the exhaust port 133 when they move toward the rotation direction of the rotating body 103. A cylindrical part 102d hangs down from the lowermost part of the rotating blades 102 (102a, 102b, 102c...) of the rotating body 103. The outer circumferential surface of the cylindrical part 102d is cylindrical and extends toward the inner circumferential surface of the threaded spacer 131, approaching the inner circumferential surface of the threaded spacer 131 with a predetermined gap. The exhaust gas, which is moved to the threaded groove 131a by the rotating blade 102 and the fixed blade 123, is guided by the threaded groove 131a and conveyed to the base portion 129.

[0055] The base portion 129 is a disc-shaped component that forms the base of the turbomolecular pump 100, and is generally made of metals such as iron, aluminum, or stainless steel. Since the base portion 129 physically holds the turbomolecular pump 100 and also functions as a heat conduction path, it is preferable to use metals such as iron, aluminum, or copper that have rigidity and high thermal conductivity.

[0056] In this structure, if the rotating blade 102 and the rotor shaft 113 are driven to rotate by the motor 121, the gas is drawn out of the chamber through the intake port 101 by the action of the rotating blade 102 and the fixed blade 123. The rotational speed of the rotating blade 102 is typically 20,000 rpm to 90,000 rpm, and the circumferential speed at the end of the rotating blade 102 reaches 200 m / s to 400 m / s. The exhaust gas drawn in from the intake port 101 passes between the rotating blade 102 and the fixed blade 123 and is transferred to the base portion 129. At this time, the temperature of the rotating blade 102 rises due to frictional heat generated when the exhaust gas contacts the rotating blade 102, heat conduction generated by the motor 121, etc., but this heat is transferred to the fixed blade 123 side by radiation or conduction by the gas molecules of the exhaust gas.

[0057] The fixed blade spacers 125 are joined together on the outer periphery, and the fixed blades 123 transfer the heat received from the rotating blades 102 and the frictional heat generated when the exhaust gas comes into contact with the fixed blades 123 to the outside.

[0058] Furthermore, in the above description, it was assumed that a threaded spacer 131 was disposed on the outer periphery of the cylindrical portion 102d of the rotating body 103, and a threaded groove 131a was engraved on the inner peripheral surface of the threaded spacer 131. However, there are also cases where, conversely, a threaded groove is engraved on the outer peripheral surface of the cylindrical portion 102d, and a spacer with a cylindrical inner peripheral surface is disposed around it.

[0059] Furthermore, depending on the application of the turbomolecular pump 100, in order to prevent the gas drawn from the intake port 101 from intruding into the electrical assembly consisting of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, and the axial sensor 109, there are cases where the electrical assembly is surrounded by a stator column 122 and the stator column 122 is kept at a predetermined pressure by a cleaning gas.

[0060] In this case, a pipe (not shown) is provided on the base portion 129, through which cleaning gas is introduced. The introduced cleaning gas is sent to the exhaust port 133 through the gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and the stator of the motor 121, and between the stator column 122 and the inner circumferential cylindrical portion of the rotating blade 102.

[0061] Here, the turbomolecular pump 100 needs to be controlled based on a specific model and its inherent parameters (e.g., characteristics corresponding to the model). To store these control parameters, the turbomolecular pump 100 includes an electronic circuit section 141 within its main body. The electronic circuit section 141 comprises a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing it, and a mounting substrate 143 for mounting them. This electronic circuit section 141 is housed below, for example, a rotational speed sensor (not shown) near the center of the base portion 129 constituting the lower part of the turbomolecular pump 100, and is sealed by an airtight bottom cover 145.

[0062] Furthermore, in the semiconductor manufacturing process, some process gases introduced into the chamber possess the property of becoming solid if their pressure is higher than a predetermined value or their temperature is lower than a predetermined value. Inside the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. During the process gas's movement from the intake port 101 to the exhaust port 133, if its pressure becomes higher than a predetermined value or its temperature becomes lower than a predetermined value, the process gas becomes solid, adheres to, and accumulates inside the turbomolecular pump 100.

[0063] For example, when SiCl4 is used as a process gas in an Al etching apparatus, the vapor pressure curve shows that under low vacuum (760 torr ~ 10... -2 At low temperatures (approximately 20°C), solid products (e.g., AlCl3) precipitate and accumulate inside the turbomolecular pump 100. Consequently, if process gas precipitates accumulate inside the turbomolecular pump 100, this accumulation narrows the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. Furthermore, the aforementioned products are prone to solidification and adhesion in the high-pressure areas near the exhaust port 133 and the threaded spacer 131.

[0064] Therefore, in order to solve this problem, conventionally a heater (not shown) or an annular water-cooling pipe 149 is wound around the outer periphery of the base portion 129, etc., and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 129, for example, to control the heating of the heater or the cooling through the water-cooling pipe 149 based on the signal of the temperature sensor (hereinafter referred to as TMS. TMS: Temperature Management System) to maintain the temperature of the base portion 129 at a certain high temperature (set temperature).

[0065] Next, regarding the turbomolecular pump 100 configured in this way, an amplifier circuit 150 for excitation control of its upper radial electromagnet 104, lower radial electromagnet 105, and axial electromagnets 106A and 106B will be described. Figure 2 The diagram below shows the circuit diagram of amplifier circuit 150.

[0066] exist Figure 2 In this configuration, one end of the electromagnet coil 151, which constitutes the upper radial electromagnet 104, is connected to the positive terminal 171a of the power supply 171 via transistor 161. The other end is connected to the negative terminal 171b of the power supply 171 via current detection circuit 181 and transistor 162. Furthermore, transistors 161 and 162 are so-called power MOSFETs, having a structure in which a diode is connected between its source and drain.

[0067] At this time, the cathode terminal 161a of the diode of transistor 161 is connected to the positive terminal 171a, and the anode terminal 161b is connected to one end of the electromagnet coil 151. In addition, the cathode terminal 162a of the diode of transistor 162 is connected to the current detection circuit 181, and the anode terminal 162b is connected to the negative terminal 171b.

[0068] On the other hand, the cathode terminal 165a of the diode 165 used for current regeneration is connected to one end of the electromagnet coil 151, and its anode terminal 165b is connected to the negative terminal 171b. Similarly, the cathode terminal 166a of the diode 166 used for current regeneration is connected to the positive terminal 171a, and its anode terminal 166b is connected to the other end of the electromagnet coil 151 via the current detection circuit 181. Furthermore, the current detection circuit 181 is composed of, for example, a Hall effect current sensor or a resistive element.

[0069] The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, with 5-axis magnetic bearing control and a total of 10 electromagnets 104, 105, 106A, and 106B, the same amplifier circuit 150 is configured for each electromagnet, and the 10 amplifier circuits 150 are connected in parallel with respect to the power supply 171.

[0070] Furthermore, the amplifier control circuit 191 is, for example, composed of a digital signal processor (DSP) unit (not shown) of the control device 200, which switches the transistors 161 and 162 on / off.

[0071] The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (the signal reflecting this current value is called the current detection signal 191c) with a predetermined current command value. Furthermore, based on this comparison result, it determines the magnitude of the pulse width (pulse width times Tp1 and Tp2) generated within one control cycle Ts, which is the PWM control cycle. As a result, gate drive signals 191a and 191b with this pulse width are output from the amplifier control circuit 191 to the gate terminals of transistors 161 and 162.

[0072] Furthermore, when the rotating body 103 accelerates through a resonance point or experiences interference during constant-speed operation, position control of the rotating body 103 under high speed and strong force is required. Therefore, a high voltage of approximately 50V is used as the power supply 171 to enable a rapid increase (or decrease) in the current flowing to the electromagnet coil 151. Additionally, a capacitor (not shown) is typically connected between the positive terminal 171a and the negative terminal 171b of the power supply 171 for stabilization.

[0073] In this structure, if both transistors 161 and 162 are turned on, the current flowing to the electromagnet coil 151 (hereinafter referred to as electromagnet current iL) increases; if both are turned off, the electromagnet current iL decreases.

[0074] Furthermore, by setting one of transistors 161 and 162 to be on and the other to be off, a freewheeling current is maintained. Moreover, by allowing this freewheeling current to flow through the amplifier circuit 150, hysteresis losses in the amplifier circuit 150 can be reduced, and overall power consumption of the circuit can be kept low. Furthermore, by controlling transistors 161 and 162 in this way, high-frequency noise such as high harmonics occurring in the turbomolecular pump 100 can be reduced. Furthermore, by measuring this freewheeling current using the current detection circuit 181, the electromagnet current iL flowing through the electromagnet coil 151 can be detected.

[0075] That is, when the detected current value is smaller than the current command value, such as Figure 3 As shown, in the control loop Ts (e.g., 100 μs), both transistors 161 and 162 are turned on only once for a time equivalent to the pulse width time Tp1. Therefore, during this period, the electromagnet current iL increases toward the current value iLmax (not shown) that can flow from the positive terminal 171a to the negative terminal 171b through transistors 161 and 162.

[0076] On the other hand, when the detected current value is larger than the current command value, such as Figure 4 As shown, in the control loop Ts, both transistors 161 and 162 are turned off only once for a time equivalent to the pulse width time Tp2. Therefore, during this period, the electromagnet current iL decreases towards the current value iLmin (not shown) that can be regenerated from the negative terminal 171b to the positive terminal 171a via diodes 165 and 166.

[0077] Furthermore, in both cases, one of transistors 161 and 162 is turned on after the pulse width times Tp1 and Tp2 have elapsed. Therefore, during this period, a continuous current is maintained in the amplifier circuit 150.

[0078] Figure 5 This is a diagram showing a schematic structural example of the vacuum pump (turbomolecular pump) according to this embodiment, including the shroud 500. Furthermore, Figure 6 This is a diagram showing a schematic structural example of the rotating body according to this embodiment.

[0079] like Figure 5 As shown, the cover 500 is provided to cover the top 210 of the rotor shaft 113. By providing this cover 500, the top 210 of the rotor shaft and the through holes 220 made in the rotating blades 102 (102a, 102b, 102c...) to allow the top 210 of the rotor shaft to pass through can be completely covered. The cover 500 is fixed to the rotating blades 102 with fastening bolts 560.

[0080] Since the hood 500 comes into contact with process gases, it is preferable to apply a corrosion-resistant surface treatment.

[0081] With the help of the cover 500, the process gas taken in from the intake port 101 can be prevented from contacting the top 210 of the rotor shaft, and the process gas can also be prevented from entering the interior through the through hole 220.

[0082] Figure 7 This is a diagram illustrating a schematic structural example of the cover portion 500 according to an embodiment of the present invention. Figure 8 yes Figure 7 The three-dimensional view of the cover 500 shown.

[0083] The cover 500 is shaped like a top hat to cover the top 210 of the rotor shaft and the through hole 220, and is formed by a cap portion 510 and a washer portion 520. Since the cover 500 also has a balancing function, it is preferably as concentric as possible with the rotor shaft 113 and is a perfect circle.

[0084] The cap 510 is shaped to fit into the shape of the rotor top 210 in order to cover the rotor top 210.

[0085] Furthermore, the washer portion 520 serves not only to fix the cover portion 500 to the rotating blade 102, but also to fasten the rotating blade 102 to the rotor shaft 113, and is provided with multiple (eight in this embodiment) through holes 530 for bolts. In addition, the number of through holes 530 for bolts is not limited to eight, for example, it can also be two, four, six or other numbers.

[0086] The bolt passes through the washer portion 520 through the through hole 530. When the cover portion 500 is installed, the cover portion is fixed (fastened) to the rotating blade 102 and the rotor shaft 113 by the fastening bolt 560 (threads are cut on the side of the rotor shaft 113).

[0087] Alternatively, as a method of fixing the cover 500 to the rotating blade 102, threads can be cut on the side of the rotating blade 102.

[0088] In addition, since the fastening bolt 560 is in contact with the process gas, it is preferable to have a corrosion-resistant surface treatment or to use a corrosion-resistant material.

[0089] The washer portion 520 is also provided with screw holes 540 for counterweights. In the embodiment shown in the figure, there are 24 screw holes 540 for counterweights, but this number can be set appropriately.

[0090] In the counterweight screw hole 540, threads are cut inside for mounting the counterweight threaded part 570. Figure 7 The text indicates the situation after the counterweight threaded part 570 has been installed in the counterweight threaded hole 540.

[0091] By adjusting the balance in the counterweight screw hole 540 and installing the counterweight threaded part 570, the balance of the high-speed rotating body (rotating blade 102 and rotor shaft 113) can be corrected.

[0092] Furthermore, in this embodiment, the imbalance can be corrected while the cover 500 is fixed.

[0093] Since the threaded part 570 for the counterweight is in contact with the process gas, it is preferably corrosion-resistant. For example, a corrosion-resistant surface treatment can be applied.

[0094] In this way, the cover 500 has the function of preventing the top 210 of the rotor shaft from contacting the process gas and correcting the balance of the rotating body when the cover is installed.

[0095] A fitting portion 550 is provided on the top of the cover portion 500. The fitting portion 550 is shaped to fit with a predetermined tool during the assembly process of the rotating blade 102. By fitting with the tool, it can support and fix the rotating blade 102 via the cover portion 500, and plays a role in the rotating body assembly process described later.

[0096] The material of the cover 500 is preferably a raw material with higher corrosion resistance than that of the rotor shaft 113 (rotor shaft top 210). For example, SUS316, which has high corrosion resistance among stainless steels, can be used as the material of the cover 500.

[0097] Next, the assembly process of the rotating body in this embodiment will be described.

[0098] Figure 9 This diagram illustrates the assembly process of the rotating body (before the armature disk is fixed) in this embodiment. Figure 10This diagram illustrates the assembly process of the rotating body in this embodiment (after the armature disk is fixed). Figure 11 This diagram illustrates the assembly process (shaft fastening) of the rotating body in this embodiment.

[0099] like Figure 9 As shown, before fixing the armature disk 310, the washer 300, armature disk 310 and nut 320 are assembled in sequence.

[0100] Washer 300 is used for alignment and to prevent the magnetic flux from armature disk 310 from bypassing the circuit.

[0101] The armature disk 310 is made of magnetic material and is a disk used to exert an attractive force with the help of an electromagnet.

[0102] Nut 320 tightens and secures armature plate 310.

[0103] Next, as Figure 10 As shown, the nut 320 is tightened with tool 700 to secure the washer 300 and armature disk 310. At this time, in order to prevent the rotor shaft 113 from rotating and thus not being able to tighten, the cover 500 is secured with tool 600. The tool 600 is shaped to engage with the fitting portion 550 provided on the top of the cover 500.

[0104] Since the cover 500 is fixed (tightened) to the rotating blade 102 and the rotor shaft 113, the nut 320 can be easily tightened by fixing the fitting part 550 provided on the top of the cover 500 with the tool 600, so that the rotating blade 102 and the rotor shaft 113 will not rotate.

[0105] Next, the order of the processes will be changed to explain the assembly of the rotating body (when the shaft is tightened).

[0106] like Figure 11 As shown, the fastening bolt 560 is tightened using tool 800. At this time, in order to prevent the rotor shaft 113 from rotating and not being able to be tightened, the cover 500 is fixed using tool 600.

[0107] In this way, the cover 500 can be easily and reliably fastened to the rotating blade 102 and the rotor shaft 113.

[0108] Alternatively, a structure can be adopted in which the embodiments and variations of the present invention are combined as needed.

[0109] Furthermore, various modifications can be made to this invention as long as they do not depart from its spirit. And, of course, this invention also relates to such modified forms.

[0110] Explanation of reference numerals in the attached figures

[0111] 100 Turbomolecular Pump (Vacuum Pump)

[0112] 101 Intake port

[0113] 102 Rotating blades

[0114] 102d cylindrical section

[0115] 103 Rotational bodies

[0116] 113 Rotor shaft

[0117] 123 Fixed blades

[0118] 125 Fixed blade spacer

[0119] 127 outer cylinder

[0120] 129 Base section

[0121] 131 Threaded spacer

[0122] 131a Threaded Groove

[0123] 133 Exhaust port

[0124] 200 control device

[0125] 210 Top of rotor shaft

[0126] 220 through hole

[0127] 300 Washer

[0128] 310 Armature disk

[0129] 320 Nut

[0130] 500 Cover

[0131] 510 Hat Department

[0132] 520 Washer Section

[0133] 530 bolt through hole

[0134] 540 Screw holes for counterweights

[0135] 550 Chimeric part

[0136] 560 Fastening bolts

[0137] 570 Threaded parts for counterweights

[0138] 600, 700, 800 tools

Claims

1. A vacuum pump, comprising: A rotating body comprising a rotating shaft rotatably supported and rotating blades, the rotating blades having a through hole through which the top of the aforementioned rotating shaft passes, thereby fixing the aforementioned top through the through hole; and The cover is fixed to the rotating body in such a way that it covers the top of the aforementioned rotating shaft and the aforementioned through hole; Its features are, The aforementioned cover has a balancing function to correct the imbalance of the aforementioned rotating body, and is corrosion-resistant to the exhaust gas. The aforementioned cover includes a cap, a washer, and a fitting portion. The cap covers the top of the aforementioned rotating shaft, the washer is used to fix the aforementioned rotating blade, and the fitting portion is disposed on the top of the aforementioned cap and engages with a tool used to fix or support the aforementioned rotating body. A counterweight screw hole is provided in the aforementioned washer portion in a manner that penetrates the washer portion. The counterweight screw hole is used to install a counterweight for correcting the imbalance of the aforementioned rotating body.

2. The vacuum pump as described in claim 1, characterized in that, The aforementioned hood achieves its corrosion resistance to exhaust gases by implementing a corrosion-resistant surface treatment.

3. The vacuum pump as described in claim 1 or 2, characterized in that, The aforementioned balance correction function is performed by a balance correction weight disposed in the aforementioned balance weight screw hole provided in the aforementioned cover, and the balance correction weight is corrosion resistant to the exhaust gas.

4. The vacuum pump as described in claim 3, characterized in that, The aforementioned balancing weights underwent a surface treatment that provides corrosion resistance to the exhaust gases.

5. A rotating body comprising a rotating shaft and rotating blades rotatably supported, the rotating blades having a through hole through which the top of the rotating shaft passes, such that the top passes through and is fixed in place by the through hole, characterized in that, It also has a cover portion that is fixed to the aforementioned rotating body in such a way that it covers the top of the aforementioned rotating shaft and the aforementioned through hole; The aforementioned cover has a balancing function to correct the imbalance of the aforementioned rotating body, and is corrosion-resistant to the exhaust gas. The aforementioned cover includes a cap, a washer, and a fitting portion. The cap covers the top of the aforementioned rotating shaft, the washer is used to fix the aforementioned rotating blade, and the fitting portion is disposed on the top of the aforementioned cap and engages with a tool used to fix or support the aforementioned rotating body. A counterweight screw hole is provided in the aforementioned washer portion in a manner that penetrates the washer portion. The counterweight screw hole is used to install a counterweight for correcting the imbalance of the aforementioned rotating body.

6. A cover portion fixed to the rotating body in such a way as to cover the top of the rotating shaft and a through hole of the rotating body, the rotating body having the rotating shaft and a rotating blade rotatably supported thereon, the rotating blade having the through hole through which the top of the rotating shaft passes, the top of the rotating body passing through the through hole for fixation, characterized in that, It possesses a balancing function to correct the imbalance of the aforementioned rotating body, and is corrosion-resistant to the exhaust gas. The aforementioned cover includes a cap, a washer, and a fitting portion. The cap covers the top of the aforementioned rotating shaft, the washer is used to fix the aforementioned rotating blade, and the fitting portion is disposed on the top of the aforementioned cap and engages with a tool used to fix or support the aforementioned rotating body. A counterweight screw hole is provided in the aforementioned washer portion in a manner that penetrates the washer portion. The counterweight screw hole is used to install a counterweight for correcting the imbalance of the aforementioned rotating body.

Images