JP7696940B2 - Vacuum pump and radial magnetic bearing device - Google Patents

Description

The present invention relates to a vacuum pump and a radial magnetic bearing device.

In semiconductor manufacturing equipment, liquid crystal manufacturing equipment, electron microscopes, surface analysis equipment, microfabrication equipment, and the like, it is necessary to create a high degree of vacuum within the equipment. Vacuum pumps are used to create a high degree of vacuum within these equipment. In vacuum pumps, magnetic bearing devices that support the rotor without contact are often used as the bearing device (see, for example, Patent Document 1). Magnetic bearing devices include radial magnetic bearing devices that support the radial load of the rotor, and axial magnetic bearing devices that support the axial load of the rotor.

Patent Document 1 describes a radial magnetic bearing device in which each of a number of teeth protruding from the inner peripheral wall of an annular stator core is covered with a coil section made of a coil wire wound around a bobbin. Each tooth and the coil section covering the tooth form an electromagnet that attracts the rotor shaft with magnetic force. In other words, the radial magnetic bearing device is equipped with a number of electromagnets arranged in the circumferential direction to surround the rotor shaft.

The bobbin has a cylindrical bobbin body around which the coil wire is wound, a first flange portion on the side of the bobbin body closer to the rotor shaft, and a second flange portion on the side of the bobbin body farther from the rotor.

Incidentally, Patent Document 2 describes a vacuum pump in which a molded section is formed by molding resin to cover a radial magnetic bearing device, a displacement sensor, etc.

JP 2018-194115 A JP 2000-283161 A

The multiple bobbins forming the radial magnetic bearing device described in Patent Document 1 are arranged in the circumferential direction so as to surround the rotor shaft, so that the first flanges on the side closer to the rotor shaft are close to each other. Therefore, when the radial magnetic bearing device is covered with a molded part, the part of the molded part closer to the rotor shaft than the first flange is formed thinner, and the part connected to the molded part farther from the rotor shaft is reduced, so it is more likely to peel off. If part of the molded part peels off, electronic devices and electrical devices such as the radial magnetic bearing device may corrode due to corrosive gas contained in the exhaust gas. Furthermore, if part of the molded part peels off, the peeled molded part may fall and narrow the gap with the rotor shaft or come into contact with the rotor shaft, which may cause a breakdown of the vacuum pump.

The present invention has been made to solve the above-mentioned problems, and aims to provide a vacuum pump and a radial magnetic bearing device that can prevent the area closer to the rotor shaft than the flange of the bobbin placed on the annular electromagnet of the radial magnetic bearing device from peeling off.

The above objective is achieved by the invention described in (1) below.

(1) A vacuum pump according to the present invention is a vacuum pump having a radial magnetic bearing device arranged on the radial outside of a rotor shaft and rotatably holding the rotor shaft, and a molded part, at least a part of which is arranged on the radial inside of the radial magnetic bearing device and in close contact with the radial magnetic bearing device, wherein the radial magnetic bearing device comprises an annular electromagnet having an inner peripheral wall on which a plurality of teeth are provided at predetermined intervals in the circumferential direction of the rotor shaft, a plurality of bobbins each attached to the plurality of teeth, and a coil part having a plurality of coil wires wound around the plurality of bobbins, and the plurality of bobbins are rectangular tubes having the coil wire wound around their outer periphery and attached to the inner peripheral side of the annular stator core so as to cover the plurality of teeth. The bobbin body has a hollow rectangular shape and a flange portion that rises from the outer peripheral surface of the end of the bobbin body facing the rotor shaft and is formed in a front view from the rotor shaft side. At least one of the side end surfaces of the flange portions adjacent in the circumferential direction of the multiple bobbins attached to the multiple teeth adjacent in the circumferential direction has a communication portion that increases the circumferential gap between the flange portions in the front view. The mold portion has a through mold that penetrates the communication portion in the radial direction, an outer mold that is arranged radially outward from the through mold and formed integrally with the through mold, and an inner mold that is arranged radially inward from the through mold and formed integrally with the through mold.

In the vacuum pump described in (1) above, the inner mold of the molded part is firmly connected to the outer mold by a through mold that passes through a communication part formed in the flange. Therefore, this vacuum pump can prevent the inner mold, which is closer to the rotor shaft than the flange of the bobbin placed on the annular electromagnet of the radial magnetic bearing device, from peeling off.

(2) In the vacuum pump described in (1) above, the annular electromagnet is formed by a pair of teeth adjacent in the circumferential direction and the coil portion covering the teeth, and has a plurality of electromagnets arranged so that the magnetic poles of the pair of teeth are different, a radial displacement detection portion that detects the radial displacement of the rotor shaft is arranged between the electromagnets adjacent in the circumferential direction, the communication portion is formed on at least one of the adjacent side end faces of the two flanges that form the same electromagnet, the two teeth that are adjacent in the circumferential direction across the radial displacement detection portion and form different electromagnets are arranged so as to have the same magnetic pole, and the communication portion is not formed on the side end faces of the flanges that are adjacent in the circumferential direction across the radial displacement detection portion, but may be formed on at least one of the adjacent side end faces of the two flanges that form the same electromagnet. As a result, between two flanges that form the same electromagnet and are placed close to each other, a through mold is formed with a communicating portion that prevents the inner mold from peeling off, which is prone to peeling off. However, between two flanges that are placed apart across the radial displacement detection unit, peeling of the inner mold is less likely to occur, so no communicating portion is formed, and the reduction in strength of the bobbin can be suppressed compared to when communicating portions are formed at both side ends of the flanges.

(3) In the vacuum pump described in (1) or (2) above, the length of the communication portion in the axial direction of the rotor shaft may be longer than the minimum width of the gap between the flange portions in the circumferential direction. This increases the strength of the through mold that penetrates the communication portion compared to a case in which no communication portion is provided. Therefore, this vacuum pump can effectively prevent the inner mold from peeling off.

(4) In the vacuum pump described in (1) or (2) above, the length of the communication portion in the axial direction of the rotor shaft may be longer than the width of the circumferential gap between the two flanges at the position where the communication portion is formed. This increases the strength of the through mold that penetrates the communication portion. Therefore, this vacuum pump can effectively prevent the inner mold from peeling off.

(5) In the vacuum pump described in any one of (1) to (4) above, the communication portion may be arranged in a plurality of portions on the side end surface of the flange portion in the axial direction of the rotor shaft. In this way, the inner mold is connected to the outer mold by a plurality of through molds, and peeling can be effectively suppressed.

(6) A radial magnetic bearing device according to the present invention is a radial magnetic bearing device that is disposed radially outward of a rotor shaft and is in intimate contact with a molded section to rotatably hold the rotor shaft, and includes an annular electromagnet having an annular stator core having a plurality of teeth provided on an inner peripheral wall at predetermined intervals in the circumferential direction of the rotor shaft, a plurality of bobbins respectively mounted on the plurality of teeth, and a coil section including a plurality of coil wires wound around the plurality of bobbins, the plurality of bobbins having the coil wire wound around their outer periphery, a rectangular tubular bobbin body that is mounted to cover the plurality of teeth from the inner peripheral side of the annular stator core, and a coil section that extends from the outer periphery of the end of the bobbin body facing the rotor shaft. and a flange portion formed in a rectangular hollow shape in a front view from the rotor shaft side, wherein at least one of the side end faces of the flange portions adjacent in the circumferential direction of the plurality of bobbins attached to the plurality of teeth adjacent in the circumferential direction has a communication portion that increases the circumferential gap between the flange portions in the front view, and is in close contact with the mold portion to form a through mold that penetrates the communication portion in the radial direction, an outer mold that is disposed radially outward of the through mold and formed integrally with the through mold, and an inner mold that is disposed radially inward of the through mold and formed integrally with the through mold. Thus, when the inside of the annular stator core is covered with the mold portion, the inner mold that is on the inside of the flange is firmly connected to the outer mold that is on the outside of the flange by the through mold that passes through the communication portion formed in the flange. Therefore, the radial magnetic bearing device can prevent the inner mold covering the side closer to the rotor shaft than the flange of the bobbin arranged in the annular electromagnet from peeling off.

1 is a vertical sectional view of a vacuum pump according to an embodiment of the present invention. FIG. 2 is a circuit diagram of an amplifier circuit. 6 is a time chart showing control when a current command value is larger than a detection value. 6 is a time chart showing control when a current command value is smaller than a detection value. 2 is a vertical cross-sectional view showing a stator column, an electrical component section, and a molded section. FIG. FIG. 6 is a cross-sectional view taken along line AA in FIG. 5. FIG. 7 is an enlarged cross-sectional view of a portion of FIG. 6. 7 is a longitudinal cross-sectional view taken along line BB in FIG. 6. FIG. 2 is a perspective view showing a radial magnetic bearing device. 2 is a plan view of one of the electromagnets of the radial magnetic bearing device as viewed from the center side of the annular stator core. FIG. FIG. 13 is a cross-sectional view showing a stator column, an electrical component section, and a molded section according to a first modified example. FIG. FIG. 11 is a plan view of one of the electromagnets of the radial magnetic bearing device of the first modified example, as viewed from the center side of the annular stator core. 11A and 11B are plan views showing modified examples, in which FIG. 11A shows a second modified example, and FIG. 11B shows a third modified example.

The following describes an embodiment of the present invention with reference to the drawings. Note that the dimensions in the drawings may be exaggerated for the sake of explanation and may differ from the actual dimensions. In addition, in this specification and the drawings, components that have substantially the same functional configuration are given the same reference numerals to avoid redundant explanation.

The vacuum pump 100 according to the embodiment of the present invention is a turbomolecular pump 100 that exhausts gas by ejecting gas molecules with the rotating blades of a rotor that rotates at high speed. The turbomolecular pump 100 is used, for example, to suck and exhaust gas from a chamber of a semiconductor manufacturing device or the like. First, the basic configuration of the turbomolecular pump 100 will be described.

A longitudinal cross-sectional view of this turbomolecular 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, which has multiple rotors 102 (102a, 102b, 102c, ...) that are turbine blades for sucking in and exhausting gas, formed radially on the periphery in multiple stages. A rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is supported in the air and position-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.

The upper radial electromagnets 104 are arranged in pairs on the X-axis and Y-axis. Four upper radial sensors 107 are provided in close proximity 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, which 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 rotor 103 fixed thereto, and send it to the control device 200.

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 the position signal detected by the upper radial sensor 107, and the amplifier circuit 150 (described later) shown in FIG. 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.

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.

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 the axial position signal is sent to control device 200.

In the control device 200, a compensation circuit having, for example, a PID adjustment function generates 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 amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 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.

In this way, the control device 200 appropriately adjusts the magnetic force that the axial electromagnets 106A and 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. 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.

On the other hand, the motor 121 has multiple magnetic poles arranged circumferentially to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 so as to rotate the rotor shaft 113 via electromagnetic forces acting between the magnetic poles and the rotor shaft 113. In addition, the motor 121 incorporates a rotational speed sensor, such as a Hall element, resolver, or encoder (not shown), and the rotational speed of the rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

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

Multiple 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 by collision. The fixed blades 123 (123a, 123b, 123c...) are made of metals such as aluminum, iron, stainless steel, copper, etc., or alloys containing these metals as components.

The fixed blades 123 are also formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged in a staggered manner with the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral end of the fixed blades 123 is supported by being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, ...).

The fixed wing spacer 125 is a ring-shaped member, and is made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a small gap between them. 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 is connected to 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.

Furthermore, depending on the application of the turbomolecular pump 100, a threaded spacer 131 (fixed member) 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 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 circumferential surface. The helical direction of the thread groove 131a is the direction in which the molecules of the exhaust gas are transported toward the exhaust port 133 when they move in the rotation direction of the rotor 103. 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, ...). The outer peripheral surface of the cylindrical portion 102d is cylindrical and protrudes toward the inner peripheral surface of the thread groove spacer 131, and is adjacent to the inner peripheral surface of the thread groove spacer 131 with a predetermined gap between them. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blade 123 is guided by the thread groove 131a and sent to the base portion 129.

The base portion 129 is a disk-shaped member 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 portion 129 not only physically holds the turbomolecular pump 100, but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the rotor 102 and the fixed blades 123 act to draw exhaust gas from the chamber through the intake port 101. 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 drawn in from the intake port 101 passes between the rotor 102 and the fixed blades 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, but this heat is transferred to the fixed blades 123 side by radiation or conduction by gas molecules of the exhaust gas.

The fixed blade spacers 125 are joined together at their outer periphery and transmit to the outside heat received by the fixed blades 123 from the rotor blades 102 and frictional heat generated when exhaust gas comes into contact with the fixed blades 123.

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 threaded groove 131a is engraved on the inner periphery of the threaded spacer 131. However, the opposite may also be true, where a threaded groove is engraved on the outer periphery of the cylindrical portion 102d, and a spacer having a cylindrical inner periphery is disposed around it.

Depending on the application of the turbomolecular pump 100, the electrical equipment section may be covered by a stator column 122 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., and the inside of the stator column 122 may be kept at a predetermined pressure by purging gas.

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 the gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102.

The turbomolecular pump 100 requires control based on the model identification and individually adjusted unique parameters (e.g., various characteristics corresponding to the model). 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 EEP-ROM, 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), for example near the center of the base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom cover 145.

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 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 pressure of the process gas becomes higher than a predetermined value or its 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 turbomolecular pump 100.

For example, when _SiCl4 is used as a process gas in an Al etching apparatus, at low vacuum (760 [torr] to 10 ^-2 [torr]) and low temperature (about 20° C.), a solid product (e.g., _AlCl3 ) precipitates and accumulates inside the turbomolecular pump 100, as can be seen from the vapor pressure curve. 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 product is prone to solidification and adhesion in high pressure areas near the exhaust port 133 and near the thread groove spacer 131.

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

Next, regarding the turbomolecular pump 100 configured in this manner, we will explain 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. A circuit diagram of this amplifier circuit 150 is shown in Figure 2.

In FIG. 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to the positive pole 171a of the power supply 171 via the transistor 161, and the other end is connected to the negative pole 171b of the power supply 171 via the current detection circuit 181 and the 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.

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

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 pole 171b. Similarly, the current regeneration diode 166 has its cathode terminal 166a connected to the positive pole 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 electrical resistance element.

The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled on 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.

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 is configured to switch the transistors 161 and 162 on and off.

The amplifier control circuit 191 compares 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, it determines the size of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control. 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 transistors 161, 162.

When the rotor 103 passes through a resonance point during accelerated operation or when a disturbance occurs during constant speed operation, it is necessary to control the position of the rotor 103 at high speed and with strong force. For this reason, a 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.

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

Furthermore, 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.

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

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

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

<Present embodiment>
Next, a vacuum pump 100 according to this embodiment will be described. As shown in Figures 1 and 5, the vacuum pump 100 has two radial magnetic bearing devices 210 arranged on the outer side of the rotor shaft 113 in the radial direction and rotatably holding the rotor shaft 113. The vacuum pump 100 has, inside the stator column 122, an electrical equipment section 220 including electric devices and electronic devices, and a molded section 300 that protects the electrical equipment section 220 from corrosive gases contained in the exhaust gas.

One of the radial magnetic bearing devices 210 has an upper radial electromagnet 104, which is an annular electromagnet 230, and rotatably supports the upper part of the rotor shaft 113, and the other radial magnetic bearing device 210 has a lower radial electromagnet 105, which is an annular electromagnet 230, and rotatably supports the lower part of the rotor shaft 113. Note that only one radial magnetic bearing device 210 may be provided in the vacuum pump 100.

As shown in Figures 6 to 10, each of the annular electromagnets 230 includes an annular stator core 240 and a plurality of coil portions 250 attached to the annular stator core 240.

The annular stator core 240 is formed by stacking multiple electromagnetic steel plates 241 (e.g., silicon steel plates) of the same shape in the axial direction Z. The annular stator core 240 has an annular portion 242 and multiple teeth 244 protruding from an inner peripheral wall 243 of the annular portion 242 toward the center O of the annular stator core 240 (which is also the center O of the rotor shaft 113). The multiple teeth 244 are arranged side by side at predetermined intervals in the circumferential direction C of the annular stator core 240 (which is also the circumferential direction C of the rotor shaft 113). The shape of a cross section perpendicular to the protruding direction of the teeth 244 is rectangular. A coil portion 250 is attached to each tooth 244.

Each coil section 250 has a bobbin 251 and a coil wire 252 wound multiple times around the outer circumference of the bobbin 251.

As shown in Figures 7 to 11, the bobbin 251 has a bobbin body 253 around which the coil wire 252 is wound, a first flange 254, and a second flange 255. The bobbin 251 is made of an insulating material such as resin.

The bobbin body 253 is a cylindrical body with through holes 256 formed therein into which the teeth 244 can be inserted. The cross-sectional shape of the bobbin body 253 perpendicular to the penetrating direction of the through holes 256 is rectangular corresponding to the cross-sectional shape of the teeth 244. In other words, the bobbin body 253 is a rectangular cylindrical body (angled tube). The coil wire 252 is wound multiple times around the outer circumferential surface of the bobbin body 253.

The first flange 254 is formed in a flat plate shape at the end of the bobbin body 253 located on the center O side of the annular stator core 240, protruding outward (away from the axis of the through hole 256) from the outer circumferential surface of the bobbin body 253 at a substantially right angle. When viewed from the front from the center O side (rotor shaft 113 side) of the annular stator core 240, the first flange 254 is formed in a rectangular hollow shape with the through hole 256 opening at the center. The first flange 254 and the second flange 255 serve to hold the wound coil wire 252, so the larger the flat protruding portion, the greater the amount of winding of the coil wire 252.

The first flange portion 254 has side end faces 257 formed at both ends in the circumferential direction C. Each side end face 257 has a proximity portion 258 extending along the axial direction Z of the rotor shaft 113 and two notched communication portions 259. Only one communication portion 259 may be formed on one side end face 257, or three or more may be formed. The communication portion 259 is formed by cutting out a predetermined depth from the proximity portion 258. In any two bobbins 251 arranged in the circumferential direction C of the rotor shaft 113, the side end faces 257 of each first flange portion 254 are adjacent to each other with a gap in the circumferential direction C. In a front view from the center O side of the annular stator core 240, as shown in FIG. 10, the two adjacent side end faces 257 form a first gap 260 at the proximity portion 258 and a second gap 261 at the communication portion 259. Each annular electromagnet 230 is placed on the teeth 244 from the inner peripheral wall 243 side of the annular stator core 240, but all the teeth 244 protrude toward the center O of the annular stator core 240. Therefore, in order to place the coil portion 250 on each of the adjacent teeth 244, the coil portions 250 must be arranged so as not to interfere with each other. In order to prevent the coil portions 250 from interfering with each other, it is preferable that the first flange portions 254 of the bobbins 251 adjacent to each other in the circumferential direction C are spaced apart without contacting each other. However, if the dimension of the first flange portion 254 in the circumferential direction C is reduced in order to increase the interval between the first flange portions 254 of the bobbins 251 adjacent to each other in the circumferential direction C, the amount of winding of the coil wire 252 will be reduced, and the performance (attraction force) of the electromagnet 270 may be reduced.

Therefore, in order to avoid a decrease in the performance of the electromagnet 270, it is preferable that the dimensions of the first flanges 254 of the multiple bobbins 251 adjacent to each other in the circumferential direction C are set as large as possible without causing interference.

On the other hand, if the spacing between the first flanges 254 of the multiple bobbins 251 adjacent in the circumferential direction C is narrowed, when the coil section 250 is covered with the mold section 300, the strength of the through mold 301 that penetrates the gap of the first flange 254 cannot be sufficiently ensured, and the connection between the inner mold 303 on the inside of the first flange 254 and the outer mold 302 on the outside of the first flange 254 becomes insufficient, which may cause the inner mold 303 to peel off. To solve this problem, the communication section 259 exists.

The first gap 260 is formed with the narrowest width W1 between two first flanges 254 adjacent to each other in the circumferential direction C. The widths W1 of the first gaps 260 arranged at different positions in the axial direction Z are the same in this embodiment, but may be different.

The second gap 261 is formed between two first flanges 254 adjacent to each other in the circumferential direction C, with a width W2 that is wider than the width W1 of the first gap 260 in the circumferential direction C. Each second gap 261 is formed between two first gaps 260 in the axial direction Z. That is, the multiple first flanges 254 adjacent to each other in the circumferential direction C have portions on both the upstream side and downstream side of the communication portion 259 that are formed with a width W1 narrower than the second gap 261. The widths W2 of the second gaps 261 arranged at different positions in the axial direction Z are the same in this embodiment, but may be different.

The length L2 of the second gap 261 in the axial direction Z is longer than the width W1 of the first gap 260 in the circumferential direction C, and is also longer than the width W2 of the second gap 261 in the circumferential direction C. If the length L2 of the second gap 261 in the axial direction Z is too small, it is difficult to sufficiently secure the communication portion 259 through which the resin molded part 300 described later penetrates in the radial direction. In contrast, the length L2 of the second gap 261 in the axial direction Z is longer than the width W1 of the first gap 260 in the circumferential direction C, and is also longer than the width W2 of the second gap 261 in the circumferential direction C, so that the communication portion 259 through which the molded part 300 penetrates can be sufficiently wide. As a result, the strength of the molded part 300 penetrating the communication portion 259 in the radial direction can be improved, and the passability of the molten resin to the communication portion 259 before the molded part 300 is molded can be improved. In this embodiment, the two side end faces 257 of the first flange 254 are formed in plane symmetry, but they do not have to be formed in plane symmetry.

The sum of the lengths L2 in the axial direction Z of all the second gaps 261 formed in one side end face 257 may be more than half the length L1 in the axial direction Z of this side end face 257, but it may also be less than half. If it is more than half, the strength of the molded part 300 that penetrates the communicating part 259 in the radial direction can be improved, and the passability of the molten resin to the communicating part 259 before the molded part 300 is molded can be improved. In addition, it is preferable that the communicating part 259 is located near the center of the side end face 257 in the axial direction Z.

As shown in Figures 6 to 10, the annular electromagnet 230 has four electromagnets 270 arranged at equal intervals of 90 degrees in the circumferential direction C. As shown in Figure 6, the four electromagnets 270 are arranged in pairs on each of the X-axis and Y-axis that are perpendicular to a plane perpendicular to the axial direction Z. That is, two electromagnets 270 in a pair are arranged on either side of the center O of the annular electromagnet 230 on the X-axis. The other two electromagnets 270 in the pair are arranged on either side of the center O of the annular electromagnet 230 on the Y-axis. The number of electromagnets 270 does not have to be four.

Each electromagnet 270 has the same structure. Each electromagnet 270 has a first electromagnet 271 and a second electromagnet 272 adjacent to each other in the circumferential direction C. The first electromagnet 271 and the second electromagnet 272 are uniaxial electromagnets 270 formed symmetrically at an angle α. As shown in Figures 6 to 10, each of the first electromagnet 271 and the second electromagnet 272 is formed by one tooth 244 and one coil portion 250 covering the tooth 244. The pair of the first electromagnet 271 and the second electromagnet 272 has different polarities. To achieve this configuration, the coil wires 252 of the first electromagnet 271 and the second electromagnet 272 adjacent to each other to form one electromagnet 270 are wound in opposite directions with respect to the tooth 244.

The first electromagnet 271 and the second electromagnet 272 adjacent to each other between different electromagnets 270 adjacent to each other in the circumferential direction C have the same polarity. In other words, the first electromagnet 271 and the second electromagnet 272 adjacent to the boundary between different electromagnets 270 adjacent to each other in the circumferential direction C have the same polarity. To achieve this configuration, the coil wires 252 of the first electromagnet 271 and the second electromagnet 272 adjacent to each other and having the same polarity are wound in the same direction around the teeth 244. As a result, the magnetic flux generated from the adjacent electromagnets 270 is canceled out, and the magnetic flux is reduced between the different electromagnets 270 adjacent to each other in the circumferential direction C.

As shown in FIGS. 5 to 8, the molded section 300 is formed by molding inside the stator column 122 to improve the corrosion resistance of the electrical equipment section 220 against corrosive gas. The molded section 300 covers the electrical equipment section 220 and fills the gaps in the electrical equipment section 220. The electrical equipment section 220 is a section that includes electrical equipment and electronic equipment, and in this embodiment, includes the upper radial sensor 107 (radial displacement detection section 280), the upper radial electromagnet 104 (annular electromagnet 230), the motor 121, the lower radial electromagnet 105 (annular electromagnet 230), and the lower radial sensor 108 (radial displacement detection section 280). When molding the molded section 300, a cylindrical nest (not shown) is inserted into the inside of the stator column 122 from the lower opening side of the stator column 122 before filling the molded section 300. Next, for example, a thermosetting epoxy resin material is filled to cover the electrical equipment section 220 and form a cylindrical inner peripheral surface of the resin mold inside the stator column 122. After the molding operation is completed, the cylindrical inner peripheral surface of the molded resin mold is cut to expose the magnetic poles of the upper radial sensor 107, the upper radial electromagnet 104, the motor 121, the lower radial electromagnet 105, and the lower radial sensor 108. The material of the molded section 300 is not particularly limited as long as it can be molded.

The mold section 300 has a through mold 301 and a narrow mold 304 that penetrate radially between two adjacent first flanges 254 in the circumferential direction C near each of the upper radial electromagnet 104 and the lower radial electromagnet 105, which are the annular electromagnets 230, an outer mold 302 that is arranged radially outside the through mold 301 and the narrow mold 304, and an inner mold 303 that is arranged radially inside the through mold 301 and the narrow mold 304.

The narrow mold 304 penetrates the adjacent portion 258 that forms the narrow first gap 260 in the radial direction of the rotor shaft 113. The through mold 301 penetrates the communicating portion 259 that forms the wide second gap 261 in the radial direction of the rotor shaft 113.

As shown in Figures 6 to 8, the inner mold 303 is formed integrally with the through mold 301 and the narrow mold 304, and is in close contact with the surface of the first flange 254 facing the rotor shaft 113 (the surface facing the center O of the annular electromagnet 230) and the outer peripheral surface of the portion of the tooth 244 that protrudes radially inward beyond the first flange 254.

The outer mold 302 is formed integrally with the through mold 301 and the narrow mold 304, and is in close contact with the radially outer surface of the first flange 254, the coil wire 252, the second flange 255, and the inner wall 243 of the annular portion 242.

Next, the operation of the vacuum pump 100 according to this embodiment will be described.

In this embodiment, the outer mold 302 and the inner mold 303 are integrally molded by a narrow mold 304 that penetrates the narrow first gap 260 and a through mold 301 that penetrates the wide second gap 261. Therefore, the inner mold 303 is firmly connected to the outer mold 302 by the through mold 301 and is not easily peeled off from the outer mold 302. In addition, when molding the molded part 300, a wide second gap 261 is formed between the first flange parts 254 adjacent to each other in the circumferential direction C, so that even if a narrow first gap 260 is formed between the first flange parts 254, the resin is likely to be filled evenly up to the narrow area. Therefore, filling defects are unlikely to occur in the molded part 300. Therefore, the vacuum pump 100 can suppress a decrease in the strength of the molded part 300 and a decrease in the corrosion resistance of the electrical part 220.

As described above, the vacuum pump 100 according to this embodiment is a vacuum pump 100 having a radial magnetic bearing device 210 arranged radially outside the rotor shaft 113 and rotatably holding the rotor shaft 113, and a molded part 300, at least a part of which is arranged radially inside the radial magnetic bearing device 210 and in close contact with the radial magnetic bearing device 210. The radial magnetic bearing device 210 is provided with an annular stator core 240 having a plurality of teeth 244 provided on an inner peripheral wall 243 at predetermined intervals in the circumferential direction C of the rotor shaft 113, and an annular electromagnet 230 having a coil part 250 including a plurality of bobbins 251 each attached to the plurality of teeth 244 and a plurality of coil wires 252 wound around the bobbins 251. The plurality of bobbins 251 have coil wires 252 wound around their outer periphery and are connected to the plurality of teeth from the inner peripheral side of the annular stator core 240. and a first flange portion 254 that rises from an outer circumferential surface of an end portion of the bobbin body 253 facing the rotor shaft 113 and is formed in a rectangular hollow shape when viewed from the front from the rotor shaft 113 side. At least one of side end surfaces 257 of the first flange portion 254 adjacent in the circumferential direction C of the plurality of bobbins 251 attached to the plurality of teeth 244 adjacent in the circumferential direction C is The first flanges 254 have a communicating portion 259 that increases the gap in the circumferential direction C between the first flanges 254, and the molded portion 300 has a through mold 301 that penetrates the communicating portion 259 in the radial direction, an outer mold 302 that is disposed radially outward of the through mold 301 and formed integrally with the through mold 301, and an inner mold 303 that is disposed radially inward of the through mold 301 and formed integrally with the through mold 301. As a result, in the vacuum pump 100 according to this embodiment, the inner mold 303 of the molded portion 300 is firmly connected to the outer mold 302 by the through mold 301 that passes through the communicating portion 259 formed in the first flanges 254. Therefore, the vacuum pump 100 can prevent the inner mold 303, which is closer to the rotor shaft 113 than the first flange 254 of the bobbin 251 arranged on the annular electromagnet 230 of the radial magnetic bearing device 210, from peeling off.

The length L2 of the communication portion 259 in the axial direction Z of the rotor shaft 113 is longer than the minimum width W1 of the gap in the circumferential direction C between the first flange portions 254. This increases the strength of the through mold 301 that penetrates the communication portion 259 compared to a case in which the communication portion 259 is not provided. Therefore, the vacuum pump 100 can effectively prevent the inner mold 303 from peeling off.

The length L2 of the communication portion 259 in the axial direction Z of the rotor shaft 113 is longer than the width W2 of the gap in the circumferential direction C between the two first flanges 254 at the position where the communication portion 259 is formed. This increases the strength of the through mold 301 that penetrates the communication portion 259. Therefore, the vacuum pump 100 can effectively prevent the inner mold 303 from peeling off.

The communication parts 259 are arranged in multiple locations on the side end surface 257 of the first flange 254 in the axial direction Z of the rotor shaft 113. As a result, the inner mold 303 is connected to the outer mold 302 by multiple through molds 301, effectively preventing peeling.

In addition, the radial magnetic bearing device 210 in this embodiment is a radial magnetic bearing device 210 that is disposed radially outside the rotor shaft 113 and rotatably holds the rotor shaft 113, and includes an annular stator core 240 having a plurality of teeth 244 provided on an inner peripheral wall 243 at predetermined intervals in the circumferential direction C of the rotor shaft 113, and an annular electromagnet 230 having a coil section 250 including a plurality of bobbins 251 each attached to the plurality of teeth 244 and a plurality of coil wires 252 wound around the bobbins 251, and the plurality of bobbins 251 have coil wires 252 wound around their outer peripheries. The bobbin 251 includes a rectangular cylindrical bobbin body 253 that is attached to the inner circumferential side of the annular stator core 240 by covering the multiple teeth 244, and a first flange portion 254 that rises from the outer circumferential surface of the end portion of the bobbin body 253 facing the rotor shaft 113 and is formed in a rectangular hollow shape when viewed from the front from the rotor shaft 113 side, and at least one of the side end surfaces 257 of the first flange portion 254 adjacent in the circumferential direction C of the multiple bobbins 251 attached to the multiple teeth 244 adjacent in the circumferential direction C has a communicating portion 259 that increases the gap in the circumferential direction C between the first flange portions 254 when viewed from the front. As a result, when the inside of the annular stator core 240 of the radial magnetic bearing device 210 is covered by the mold part 300, the inner mold 303 on the inside of the first flange 254 is firmly connected to the outer mold 302 on the outside of the first flange 254 by the through mold 301 that passes through the communication part 259 formed in the first flange 254. Therefore, the radial magnetic bearing device 210 can prevent the inner mold 303 that covers the side closer to the rotor shaft 113 than the first flange 254 of the bobbin 251 arranged in the annular electromagnet 230 from peeling off.

Note that the present invention is not limited to the above-mentioned embodiment, and various modifications and combinations are possible within the technical concept of the present invention. For example, as in the first modified example shown in Figs. 12 and 13, a radial displacement detection unit 280 that detects the radial displacement of the rotor shaft 113 may be arranged between electromagnets 270 adjacent to each other in the circumferential direction C. In the first modified example, the radial displacement detection unit 280 can be arranged at the same position as the electromagnets 270 in the axial direction Z, so that the dimension of the vacuum pump 100 in the axial direction Z can be reduced. The radial displacement detection unit 280 is a known displacement sensor, such as an inductance type displacement sensor. Each of the radial displacement detection units 280 has a pair of magnetic poles 283, 283 formed by winding a sensor coil 282 around two claws 281 protruding from the inner circumferential wall 243 of the annular stator core 240. The pair of magnetic poles 283, 283 have different polarities because the sensor coil 282 is wound in the opposite directions.

The first electromagnet 271 and the second electromagnet 272 adjacent to each other in the circumferential direction C have the same polarity on the rotor shaft 113 side. Therefore, each radial direction displacement detection unit 280 is disposed between the first electromagnet 271 and the second electromagnet 272 having the same polarity adjacent to each other in the circumferential direction C. As a result, in the region where the radial direction displacement detection unit 280 is disposed, the magnetic flux generated from the adjacent electromagnets 270 is cancelled out, so that the effect of the magnetic flux of the electromagnet 270 on the radial direction displacement detection unit 280 is reduced.

In the first modified example, since the radial displacement detection unit 280 is disposed at the same position as the electromagnet 270 in the axial direction Z, it is difficult to secure a wide gap between the two first flanges 254 adjacent in the circumferential direction C of the first electromagnet 271 and the second electromagnet 272 forming the same electromagnet 270. However, in the first modified example, since the communication portion 259 is formed on at least one side end surface 257 of the two first flanges 254 adjacent in the circumferential direction C, where it is difficult to secure a wide gap, the inner mold 303 is firmly connected to the outer mold 302 by the through mold 301, and the inner mold 303 can be prevented from peeling off. In addition, when molding the molded part 300, a wide flow path can be secured between the two adjacent first flanges 254, where it is difficult to secure a wide gap, and it is easy to fill the resin evenly to the desired range. In addition, a sufficient gap can be secured between the two first flanges 254 that are spaced apart and sandwich the radial displacement detection unit 280, so peeling of the inner mold 303 is unlikely to occur. Therefore, there is no need to form a communication portion 259 in the two first flanges 254 that sandwich the radial displacement detection unit 280, and a decrease in the strength of the bobbin 251 due to the formation of the communication portion 259 in the first flanges 254 can be prevented.

The communication portion 259 of the first flange 254 is not limited in configuration as long as it can widen the first gap 260. Therefore, for example, as in the second modified example shown in FIG. 14(A), the communication portion 259 of the first flange 254 may have an arc-shaped body instead of a straight body when viewed from the center O side of the annular stator core 240. That is, the width of the second gap 261 formed by the communication portion 259 in the circumferential direction C may change along the axial direction Z. As in the third modified example shown in FIG. 14(B), the communication portion 259 may be formed by a step rather than a recess.

100 Vacuum pump 104 Upper radial electromagnet (annular electromagnet)
105 Lower radial electromagnet (annular electromagnet)
REFERENCE SIGNS LIST 113 rotor shaft 122 stator column 210 radial magnetic bearing device 220 electrical equipment section 230 annular electromagnet 240 annular stator core 241 electromagnetic steel plate 242 annular section 243 inner circumferential wall 244 teeth 250 coil section 251 bobbin 252 coil wire 253 bobbin body 254 first flange section (flange section)
255 Second flange portion 256 Through hole 257 Side end surface 258 Proximal portion 259 Communication portion 260 First gap 261 Second gap 270 Electromagnet 271 First electromagnet 272 Second electromagnet 280 Radial direction displacement detection portion 300 Molded portion 301 Through mold 302 Outer mold 303 Inner mold 304 Narrow mold C Circumferential direction Z Axial direction

Claims (6)

A vacuum pump having a radial magnetic bearing device disposed radially outward of a rotor shaft and rotatably holding the rotor shaft, and a molded portion, at least a portion of which is disposed radially inward of the radial magnetic bearing device and in intimate contact with the radial magnetic bearing device,
The radial magnetic bearing device includes:
an annular stator core having an inner peripheral wall on which a plurality of teeth are provided at predetermined intervals in the circumferential direction of the rotor shaft;
a coil portion including a plurality of bobbins respectively attached to the plurality of teeth and a plurality of coil wires wound around the plurality of bobbins;
The plurality of bobbins include
a bobbin body having a rectangular cylindrical shape, the bobbin body having the coil wire wound around its outer periphery and being attached to the annular stator core from its inner periphery so as to cover the teeth;
a flange portion that rises from an outer circumferential surface of an end portion of the bobbin body facing the rotor shaft and is formed into a rectangular hollow shape when viewed from the front from the rotor shaft side,
At least one of side end surfaces of the flange portions adjacent in the circumferential direction of the plurality of bobbins attached to the plurality of teeth adjacent in the circumferential direction has a communication portion that increases a circumferential gap between the flange portions in the front view,
The mold part includes:
a through mold that penetrates the communication portion in the radial direction;
an outer mold disposed radially outward of the through mold and integrally formed with the through mold;
an inner mold disposed radially inward of the through mold and integrally formed with the through mold. the annular electromagnet is formed by a pair of the teeth adjacent to each other in the circumferential direction and the coil portion covering the teeth, and has a plurality of electromagnets arranged such that the magnetic poles of the pair of teeth are different from each other,
a radial displacement detection unit that detects a radial displacement of the rotor shaft is disposed between the electromagnets adjacent in the circumferential direction,
two teeth adjacent to each other in the circumferential direction across the radial displacement detection portion and forming different electromagnets are arranged to have the same magnetic pole,
2. The vacuum pump according to claim 1, wherein the communication portion is not formed on the side end faces of the flange portions adjacent in the circumferential direction across the radial displacement detection portion, but is formed on at least one of the adjacent side end faces of the two flange portions that form the same electromagnet. The vacuum pump according to claim 1 or 2, characterized in that the length of the communication portion in the axial direction of the rotor shaft is longer than the minimum width of the gap between the flange portions in the circumferential direction. The vacuum pump according to claim 1 or 2, characterized in that the length of the communication portion in the axial direction of the rotor shaft is longer than the width of the circumferential gap between the two flanges at the position where the communication portion is formed. The vacuum pump according to claim 1 or 2, characterized in that the communication portion is arranged in a plurality of positions on the side end surface of the flange portion in the axial direction of the rotor shaft. A radial magnetic bearing device that is disposed radially outward of a rotor shaft and is in close contact with a molded portion to rotatably hold the rotor shaft,
an annular stator core having an inner peripheral wall on which a plurality of teeth are provided at predetermined intervals in the circumferential direction of the rotor shaft;
a coil portion including a plurality of bobbins respectively attached to the plurality of teeth and a plurality of coil wires wound around the plurality of bobbins;
The plurality of bobbins include
a bobbin body having a rectangular cylindrical shape, the bobbin body having the coil wire wound around its outer periphery and being attached to the annular stator core from its inner periphery so as to cover the teeth;
a flange portion that rises from an outer circumferential surface of an end portion of the bobbin body facing the rotor shaft and is formed into a rectangular hollow shape when viewed from the front from the rotor shaft side,
At least one of side end surfaces of the flange portions adjacent in the circumferential direction of the plurality of bobbins attached to the plurality of teeth adjacent in the circumferential direction has a communication portion that increases a circumferential gap between the flange portions in the front view,
A radial magnetic bearing device characterized in that the mold portion is adhered to the mold portion to form a through mold that penetrates the communicating portion in the radial direction, an outer mold that is positioned radially outward of the through mold and formed integrally with the through mold, and an inner mold that is positioned radially inward of the through mold and formed integrally with the through mold .

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