WO2024004849A1

WO2024004849A1 - Vacuum pump

Info

Publication number: WO2024004849A1
Application number: PCT/JP2023/023292
Authority: WO
Inventors: 透三輪田; 慶行高井; 康寛芝田
Original assignee: エドワーズ株式会社
Priority date: 2022-06-29
Filing date: 2023-06-23
Publication date: 2024-01-04
Also published as: JP2024004829A; GB202213704D0; TW202407219A

Abstract

Proposed is a vacuum pump capable of more reliably preventing the problem of an exhaust gas leakage between a partition wall and a part on which the partition wall is mounted. A vacuum pump (100) is characterized by comprising: an exterior body having an exhaust port (133); a rotating shaft (113) that is rotatably supported inside the exterior body and rotated by an electrical part; a rotor (103) that is disposed outside a housing part (122) and secured to the rotating shaft (113); a stator that is disposed on an outer circumferential side of the rotor (103); a pump flow path that is provided between an outer circumferential surface of the rotor (103) and an inner circumferential surface of the stator, and through which gas flows; a partition wall (135) that is mounted on the stator and defines a gas flow path from an outlet of the pump flow path to the exhaust port (133); a heating means (138) that heats the stator and the partition wall (135); and a seal member (136) that is attached to the mounting surfaces of the stator and the partition wall (135) to prevent intrusion of the gas.

Description

Vacuum pump

The present invention relates to a vacuum pump.

A vacuum pump such as a turbo-molecular pump is used for evacuation processing in a vacuum chamber provided in a semiconductor manufacturing device. In the semiconductor manufacturing process, there is a process in which various process gases are applied to the semiconductor substrate, and vacuum pumps are used not only to evacuate the chamber of semiconductor manufacturing equipment, but also to pump process gases from inside the chamber. It is also used when exhausting air.

Such a process gas solidifies at a point where the relationship between pressure and temperature shown in the vapor pressure curve shifts from the gas phase to the solid phase, and is precipitated as a by-product. If such by-products accumulate in the vacuum pump, the flow path of the gas to be exhausted may be narrowed, and the compression performance and exhaust performance of the vacuum pump may deteriorate. For example, the base part that makes up the exterior body of a vacuum pump and the housing part (stator column) that houses electrical components such as electromagnets and motors that drive the rotor are at low temperatures, so if exhaust gas comes into contact with these parts, byproducts will be generated. will accumulate.

To address such problems, conventional methods have been to cover at least a portion of the base portion with a partition wall to prevent exhaust gas from coming into direct contact with the base portion. For example, in Patent Document 1, a partition wall (insulating wall in Patent Document 1) is provided on the downstream side of a thread groove pump section in a vacuum pump, and by covering at least a part of the stator column and base section, which are low temperature parts, with this partition wall, This suppresses by-products from accumulating on the base and the like.

International Publication No. 2021/090738

By the way, the partition wall of Patent Document 1 is fixed to the threaded stator with, for example, bolts, as shown in FIG. 4 of the same document. At this time, the bulkhead basically comes into close contact with the threaded stator by tightening the bolts, but due to variations in processing the parts, there is a risk that the mounting surfaces of both may not make sufficient contact with each other. There is. In such a case, there was a concern that exhaust gas would leak from between the mounting surface of the partition wall and the threaded stator, resulting in by-products being deposited on the base portion and the like.

In view of these points, an object of the present invention is to provide a vacuum pump that can more reliably prevent the problem of exhaust gas leaking between the partition wall and the part to which it is attached.

The vacuum pump of the present invention includes an exterior body having an exhaust port, a housing part that houses an electrical component and is disposed inside the exterior body, and a housing part that is rotatably supported inside the exterior body and that is supported by the electrical component. a rotary shaft that rotates; a rotor disposed outside the housing portion and fixed to the rotary shaft; a stator disposed on the outer circumferential side of the rotor; an outer circumferential surface of the rotor; and an inner circumferential surface of the stator. a pump flow path provided between the pump flow path and through which gas flows; a partition wall that is attached to the stator and defines a flow path for the gas from an outlet of the pump flow path to the exhaust port; and a partition wall that connects the stator and the partition wall. A sealing member for suppressing intrusion of the gas is provided on a mounting surface between the stator and the partition wall.

Preferably, such a vacuum pump has a metal touch surface where the stator and the partition wall come into contact with each other on the upstream side of the gas with respect to the seal member on the mounting surface.

Furthermore, it is preferable that the stator and the partition wall be made of different materials.

Preferably, the partition wall is made of a material having higher thermal conductivity than the stator.

Further, it is preferable that a non-contact seal structure for suppressing the flow of the gas into the accommodating portion is provided on at least a part of the opposing surfaces where the rotor and the partition wall face each other.

Further, it is preferable that the partition wall is fixed to the stator from the axial direction of the rotating shaft with bolts.

Preferably, the stator has a through hole connected to the exhaust port, and the mounting surface is provided at a position offset from the through hole with respect to the axial direction of the rotating shaft.

In the vacuum pump of the present invention, a partition wall is attached to a stator disposed on the outer peripheral side of a rotor, and a sealing member for suppressing gas intrusion is provided on the attachment surface between the stator and the partition wall. In other words, even if, for example, there is a gap that would allow gas to leak when the two are attached due to variations in the processing of the stator or partition wall, the problem of gas leaking can be more reliably prevented by the sealing member. Can be done.

1 is a longitudinal sectional view schematically showing a first embodiment of a vacuum pump according to the present invention. 2 is a circuit diagram of an amplifier circuit of the vacuum pump shown in FIG. 1. FIG. It is a time chart which shows control when a current command value is larger than a detected value. It is a time chart showing control when a current command value is smaller than a detected value. Regarding the vacuum pump shown in FIG. 1, (a) is a partially enlarged view of part A, and (b) is a partially enlarged view of part B. Regarding the heater spacer and partition shown in FIG. 1, (a) is a perspective view showing a state in which the heater spacer and partition are combined, (b) is a perspective view of the heater spacer, and (c) is a perspective view of the partition. It is a diagram. FIG. 2 is a vertical cross-sectional view schematically showing a second embodiment of the vacuum pump according to the present invention. Regarding the vacuum pump shown in FIG. 7, (a) is a partial enlarged view of section C, and (b) is a partial enlarged view of section D. Regarding the heater spacer and partition shown in FIG. 7, (a) is a perspective view showing a state in which the heater spacer and partition are combined, (b) is a perspective view of the heater spacer, and (c) is a perspective view of the partition. It is a diagram.

Hereinafter, a turbo molecular pump, which is an embodiment of the vacuum pump according to the present invention, will be described with reference to the drawings.

A longitudinal cross-sectional view of this turbomolecular pump 100 is shown in FIG. In FIG. 1, a turbomolecular pump 100 is provided with an intake port 101 at the upper end of a cylindrical outer tube 127 (a part of the outer case). A rotating body 103 (rotor) that rotates around the central axis CA is provided inside the outer cylinder 127. The rotating body 103 includes a plurality of rotary blades 102 (102a, 102b, 102c, . . . ), which are turbine blades for sucking and exhausting gas, arranged radially and in multiple stages around the circumference. A rotor shaft 113 (rotation shaft) is attached to the center of the rotating body 103, and the rotor shaft 113 is supported and positioned in the air by, for example, a five-axis magnetic bearing. The rotating body 103 is generally made of metal such as aluminum or aluminum alloy.

In the upper radial electromagnet 104, four electromagnets are arranged in pairs on the X axis and the Y axis. Four upper radial sensors 107 are provided close to this upper radial electromagnet 104 and corresponding to each upper radial electromagnet 104 . The upper radial direction sensor 107 uses, for example, an inductance sensor or an eddy current sensor having a conduction winding, and detects the position of the rotor shaft 113 based on a change in the inductance of the conduction winding, which changes depending on the position of the rotor shaft 113. Detect. This upper radial direction sensor 107 is configured to detect a radial displacement of the rotor shaft 113, that is, the rotating body 103 fixed thereto, and send it to a control device (not shown).

In this control device, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on a position signal detected by the upper radial sensor 107, and generates an excitation control command signal for the upper radial electromagnet 104, A circuit 150 (described later) 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 high magnetic permeability material (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. Further, a lower radial electromagnet 105 and a lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107, and the lower radial position of the rotor shaft 113 is changed to the upper radial position. are adjusted in the same way.

Further,

axial electromagnets

106A and 106B are arranged vertically sandwiching a disc-shaped metal disk 111 provided at the lower part of the rotor shaft 113. The 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 the rotor shaft 113, and the axial position signal thereof is configured to be sent to the control device.

In the above control device, for example, a compensation circuit having a PID adjustment function issues excitation control command signals for each of the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial direction sensor 109. 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. , the axial electromagnet 106B attracts the metal disk 111 downward, and the axial position of the rotor shaft 113 is adjusted.

In this way, the control device appropriately adjusts the magnetic force exerted on the metal disk 111 by the

axial electromagnets

106A and 106B, magnetically levitates the rotor shaft 113 in the axial direction, and holds it in space without contact. ing. The amplifier circuit 150 that excites and controls 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 includes a plurality of magnetic poles arranged circumferentially so as to surround the rotor shaft 113. Each magnetic pole is controlled by the control device described above so as to rotationally drive the rotor shaft 113 via electromagnetic force acting between the magnetic poles and the rotor shaft 113. Further, a rotational speed sensor (not shown) such as a Hall element, a resolver, an encoder, etc. is incorporated in the motor 121, and the rotational speed of the rotor shaft 113 is detected based on a detection signal from this rotational speed sensor.

Further, a phase sensor (not shown) is attached, for example, near the lower radial direction sensor 108 to detect the rotational phase of the rotor shaft 113. In the above control device, the position of the magnetic pole is detected using both the detection signals from the phase sensor and the rotational speed sensor.

On the inner circumferential side of the outer cylinder 127 and on the outer circumferential side of the rotating body 103, a plurality of fixed blades 123 (123a, 123b, 123c, etc.) are provided with a slight gap between them and the rotary blades 102 (102a, 102b, 102c, . . . ). ...) are provided. The rotor blades 102 (102a, 102b, 102c, . . . ) are each formed to be inclined 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. There is. The fixed blades 123 (123a, 123b, 123c...) are made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components.

Similarly, the fixed blades 123 are formed to be inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged inward of the outer cylinder 127 in alternating stages with the stages of the rotary blades 102. ing. The outer peripheral end of the fixed wing 123 is supported by being inserted between a plurality of stacked fixed wing spacers 125 (125a, 125b, 125c, . . . ).

The fixed wing spacer 125 is a ring-shaped member, and is made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a slight gap therebetween. A base portion 129 (a part of the exterior body) is provided at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129 and communicates with the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) side and is transferred inside the turbo molecular pump 100 is sent to the exhaust port 133 on the downstream side.

A threaded spacer 131, a heater spacer 134, a partition wall (insulator wall) 135, a seal member 136, and a heat insulating spacer 137 are provided between the lower part of the fixed wing spacer 125 and the base portion 129. The fixed blade 123, fixed blade spacer 125, threaded spacer 131, and heater spacer 134 described above are members that constitute a part of the stator. Note that detailed explanations regarding the heater spacer 134, partition wall 135, seal member 136, and heat insulating spacer 137 will be given later.

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 spiral thread grooves 131a on its inner peripheral surface. A provision has been made. The spiral direction of the thread groove 131a is the direction in which exhaust gas molecules are transferred toward the exhaust port 133 when they move in the rotational direction of the rotating body 103. A cylindrical portion 102d is suspended from the lowest part of the rotating body 103 following the rotary blades 102 (102a, 102b, 102c, . . . ). The outer circumferential surface of the cylindrical portion 102d is cylindrical and protrudes toward the inner circumferential surface of the threaded spacer 131, and is adjacent to the inner circumferential surface of the threaded spacer 131 with a predetermined gap therebetween. There is. The threaded spacer 131 and the cylindrical part 102d function as a threaded groove pump part, and the exhaust gas transferred to the threaded groove 131a by the rotary blade 102 and the fixed blade 123 is guided to the threaded groove 131a and flows through the exhaust port. Sent to 133. Note that the function as a threaded groove pump section may be provided as desired depending on the use of the turbo molecular pump 100.

The base portion 129 is a disk-shaped member that constitutes the base of the turbo-molecular pump 100, and is generally made of metal such as iron, aluminum, or stainless steel. The base portion 129 physically holds the turbo-molecular pump 100 and also functions as a heat conduction path, so a metal with rigidity and high thermal conductivity such as iron, aluminum, or copper is used. is desirable.

In this configuration, when the rotor blade 102 is rotationally driven by the motor 121 together with the rotor shaft 113, exhaust gas is taken in from the chamber through the intake port 101 by the action of the rotor blade 102 and the fixed blade 123. The rotation speed of the rotor blade 102 is normally 20,000 rpm to 90,000 rpm, and the circumferential speed at the tip of the rotor blade 102 reaches 200 m/s to 400 m/s. The exhaust gas taken in from the intake port 101 passes through the pump flow path between the rotary blade 102 and the fixed blade 123 and between the threaded spacer 131 and the cylindrical portion 102d, and passes through the threaded spacer 131, the heater spacer 134, and the partition wall 135. It passes through a flow path defined by , and is transferred to the exhaust port 133 . At this time, the temperature of the rotor blade 102 increases due to frictional heat generated when the exhaust gas comes into contact with the rotor blade 102, conduction of heat generated by the motor 121, etc. It is transmitted to the fixed wing 123 side by conduction by molecules and the like.

The fixed blade spacers 125 are joined to each other at the outer periphery, and transmit heat received by the fixed blade 123 from the rotary blade 102 and frictional heat generated when exhaust gas comes into contact with the fixed blade 123 to the outer cylinder 127. .

Note that the above description has been made assuming that the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotating body 103, and that the threaded spacer 131 is provided with a thread groove 131a on its inner peripheral surface. However, on the contrary, a thread groove may be formed on the outer circumferential surface of the cylindrical portion 102d, and a spacer having a cylindrical inner circumferential surface may be arranged around the thread groove.

Also, depending on the use of the turbo molecular pump 100, the gas sucked from the intake port 101 may be transferred to the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, and the shaft. In order to prevent intrusion into the electrical equipment section consisting of the

directional electromagnets

106A, 106B, the axial direction sensor 109, etc., the electrical equipment section is surrounded by a stator column 122 (housing section), and the inside of this stator column 122 is filled with purge gas. In some cases, it is maintained at a predetermined pressure.

A purge port 115 is provided in the base portion 129 of this embodiment, and purge gas is introduced through this purge port 115. The introduced purge gas is sent to the exhaust port 133 through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and the stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blade 102.

Here, the turbo-molecular pump 100 requires control based on specification of the model and individually adjusted unique parameters (for example, various characteristics corresponding to the model). In order to store this control parameter, the turbo molecular pump 100 is equipped with an electronic circuit section (not shown) within its main body. This electronic circuit section is composed of a semiconductor memory such as an EEP-ROM, electronic components such as a semiconductor element for accessing the memory, a board for mounting them, and the like. This electronic circuit section is housed, for example, under a rotational speed sensor (not shown) near the center of the base section 129 constituting the lower part of the turbo-molecular pump 100, and is closed by an airtight bottom cover 145.

By the way, in the semiconductor manufacturing process, some process gases introduced into a chamber have the property of becoming solid when the pressure becomes higher than a predetermined value or the temperature becomes lower than a predetermined value. be. 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 the temperature becomes lower than 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 turbo molecules It adheres and accumulates inside the pump 100.

For example, when SiCl4 is used as a process gas in an Al etching system, solid products (for example, AlCl3 ) is precipitated and deposited inside the turbomolecular pump 100, as can be seen from the vapor pressure curve. As a result, if deposits of the process gas are deposited inside the turbo-molecular pump 100, the deposits narrow the pump flow path and cause the performance of the turbo-molecular pump 100 to deteriorate. The above-mentioned products were likely to coagulate and adhere to areas where the pressure was high near the exhaust port 133 and the threaded spacer 131.

Therefore, in order to solve this problem, conventionally, a heater (not shown) or an annular water cooling pipe (not shown) is wrapped around the outer periphery of the base part 129, etc., and a temperature sensor (for example, a thermistor) (not shown) is embedded in the base part 129. Based on the signal from the temperature sensor, the heating of the heater and the cooling by the water cooling pipe are controlled (hereinafter referred to as TMS; Temperature Management System) to maintain the temperature of the base part 129 at a constant high temperature (set temperature). There is. The turbo molecular pump 100 of this embodiment has a heater 138 (heating means) and a temperature sensor 139 attached to the heater spacer 134 for performing TMS.

Next, regarding the turbo-molecular pump 100 configured as described above, 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. A circuit diagram of this amplifier circuit 150 is shown in FIG.

In FIG. 2, an electromagnet winding 151 constituting the upper radial electromagnet 104 and the like has one end connected to a positive electrode 171a of a power supply 171 via a transistor 161, and the other end connected to a current detection circuit 181 and a transistor 162. It is connected to the negative electrode 171b of the power supply 171 via. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between their sources and drains.

At this time, the cathode terminal 161a of the diode of the transistor 161 is connected to the positive electrode 171a, and the anode terminal 161b is connected to one end of the electromagnet winding 151. Further, the transistor 162 has a diode cathode terminal 162a connected to the current detection circuit 181, and an 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 electrode 171b. Similarly, the current regeneration diode 166 has its cathode terminal 166a connected to the positive electrode 171a, and its anode terminal 166b connected to the other end of the electromagnet winding 151 via the current detection circuit 181. It has become so. The current detection circuit 181 is configured with, for example, a Hall sensor type current sensor or an electric resistance element.

The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, if the magnetic bearing is 5-axis controlled and there are a total of 10

electromagnets

104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each of the electromagnets, and 10 amplifier circuits are configured for the power supply 171. 150 are connected in parallel.

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

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

Note that when the rotational speed of the rotating body 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 rotating body 103 at high speed and with strong force. . Therefore, in order to rapidly increase (or decrease) the current flowing through the electromagnet winding 151, a high voltage of about 50 V, for example, is used as the power source 171. Further, a capacitor (not shown) is usually connected between the positive electrode 171a and the negative electrode 171b of the power source 171 in order to stabilize the power source 171.

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

Furthermore, when one of the transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By causing the flywheel current to flow 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. Further, by controlling the transistors 161 and 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.

That is, when the detected current value is smaller than the current command value, as shown in FIG. Turn both on. Therefore, the electromagnet current iL during this period increases toward a current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.

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

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

Next, the above-mentioned heater spacer 134, partition wall 135, seal member 136, and heat insulating spacer 137 will be explained in detail.

The heater spacer 134 is a ring-shaped member as shown in FIGS. 1, 5, and 6, and is made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals. configured. As an example, the heater spacer 134 is preferably made of a high-strength material to ensure strength at high temperatures, and in this embodiment, it is made of stainless steel in consideration of this point. As shown in the figure, a threaded spacer 131 is attached to the top of the heater spacer 134. Furthermore, mounting holes for mounting a heater 138 and a temperature sensor 139 are provided on the side surface of the heater spacer 134, and the heater 138 and temperature sensor 139 are held by the heater spacer 134.

Further, as shown in FIG. 5, the heater spacer 134 has a flat metal touch surface 134a extending horizontally at the lower part on the inside in the radial direction, and a flat metal touch surface 134a extending vertically downward from the outside in the radial direction of the metal touch surface 134a. radial positioning surface 134b, and a flank surface 134c having a larger inner diameter than radial positioning surface 134b and located below radial positioning surface 134b. Further, the lower surface of the heater spacer 134 is provided with an annular recess 134d to which a seal member 136 is attached. As shown, the partition wall 135 is attached to the metal touch surface 134a, the radial positioning surface 134b, the flank surface 134c, and the annular recess 134d of the heater spacer 134. This portion is referred to as the mounting surface of the heater spacer 134. The metal touch surface 134a is provided with a plurality of female screw portions 134e arranged at intervals in the circumferential direction.

Further, the heater spacer 134 includes a circular through hole 134f that passes through the heater spacer 134 in the radial direction, as shown in FIGS. 6(a) and 6(b). The through hole 134f communicates with the exhaust port 133 when the turbo molecular pump 100 is assembled. The through hole 134f is provided at a position that overlaps the metal touch surface 134a, the radial positioning surface 134b, and the flank surface 134c with respect to the axial direction (direction along the central axis CA) of the heater spacer 134. .

The partition wall 135 is a ring-shaped member as shown in FIGS. 1, 5, and 6, and is made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals. be done. The partition wall 135 is preferably heated by heat from a heater 138 attached to the heater spacer 134 as described later, and in this embodiment, taking this point into consideration, the partition wall 135 is made of a material having higher thermal conductivity than the heater spacer 134. The partition wall 135 is made of (for example, aluminum).

Furthermore, the partition wall 135 of this embodiment includes an annular wall portion 135a in the shape of an annular plate. A cylindrical inner circumferential wall portion 135b extending upward is provided at the inner edge of the annular wall portion 135a, and a folded portion protruding radially outward is provided at the upper end of the inner circumferential wall portion 135b. 135c (not shown in FIG. 6) is provided. The partition wall 135 also includes a cylindrical outer circumferential wall portion 135e extending upward from a portion located radially inward from the outer edge portion 135d of the partition wall 135. The upper surface of the outer peripheral wall portion 135e is a flat surface extending in the horizontal direction. Hereinafter, the upper surface of the outer peripheral wall portion 135e will be referred to as a metal touch surface 135f. Note that the partition wall 135 is attached to the outer edge portion 135d, the outer peripheral wall portion 135e, and the metal touch surface 135f of the heater spacer 134 as shown in the figure, and in the following description, the outer edge portion 135d, the outer peripheral wall portion 135e and the portion extending to the metal touch surface 135f is referred to as the attachment surface of the partition wall 135.

The outer circumferential wall portion 135e is provided with a plurality of bolt holes 135g arranged at intervals in the circumferential direction and passing through the outer circumferential wall portion 135e in the vertical direction. The bolt through hole 135g is provided at a position corresponding to the female threaded portion 134e. Then, with the mounting surface of the heater spacer 134 and the mounting surface of the partition wall 135 facing each other, the bolt 140 is inserted into the bolt through hole 135g and screwed into the female threaded portion 134e, thereby attaching the partition wall 135 to the heater spacer 135. It can be attached to.

Further, the partition wall 135 includes a semicircular notch 135h that radially penetrates the outer circumferential wall 135e, as shown in FIG. 6(c). The cutout portion 135h is combined with the through hole 134f to form one hole when the partition wall 135 is attached to the heater spacer 134 as shown in FIG. 6(a).

The sealing member 136 is formed of an elastic material (nitrile rubber, fluororubber, silicone rubber, etc.) into an annular shape. Equipped with a function to suppress the intrusion of gas. The seal member 136 of this embodiment is an O-ring.

The heat insulating spacer 137 is a ring-shaped member as a whole, and is made of a material with low thermal conductivity (hard to transmit heat). The material of the heat insulating spacer 137 is, for example, stainless steel. As illustrated, the heat insulating spacer 137 is interposed between the base portion 129 and the heater spacer 134, and the base portion 129 is insulated from the heater spacer 134.

In the turbo molecular pump 100 configured with such members, when the partition wall 135 is attached to the heater spacer 134 with the bolts 140, the seal member 136 is in close contact with the lower surface of the annular recess 134d and the upper surface of the outer edge portion 135d. Furthermore, when the partition wall 135 is attached to the heater spacer 134, the radial positioning surface 134b and the upper outer circumferential surface of the outer peripheral wall portion 135e are in contact with each other, and the metal touch surface 134a and the metal touch surface 135f are in contact with each other. 134 in the radial direction and also in the vertical direction. Note that the flank surface 134c located below the radial positioning surface 134b has a larger diameter than the inner diameter of the radial positioning surface 134b, so when the partition wall 135 is attached to the heater spacer 134, basically the outer circumferential wall portion It does not contact the outer peripheral surface of 135e. That is, when forming the radial positioning surface 134b and the flank surface 134c, only the radial positioning surface 134b requires machining precision, so that the cost of machining the heater spacer 134 can be suppressed.

When the partition wall 135 is attached to the heater spacer 134, the lower part of the threaded spacer 131 and the cylindrical part 102d is defined by the threaded spacer 131, the heater spacer 134, and the partition wall 135, and the threaded spacer 131 and the cylindrical part 102d An annular flow path is formed that communicates with the pump flow path between the holes and the through hole 134f. Further, the folded portion 135c of the partition wall 135 is located directly below the cylindrical portion 102d, and a gap is provided between the upper surface of the folded portion 135c and the lower surface of the cylindrical portion 102d. This gap is formed to such an extent that the cylindrical part 102d and the folded part 135c do not come into contact with each other when the rotating body 103 rotates, and the gas flowing through the annular flow path described above does not flow into the stator column 122 through this gap. It is narrowed and functions as a non-contact sealing structure.

Furthermore, the partition wall 135 attached to the heater spacer 134 with bolts 140 is thermally connected to the heater spacer 134. Therefore, the heat from the heater 138 is sufficiently transmitted from the heater spacer 134 to the partition wall 135, so that the partition wall 135 can be effectively heated. Although the inner peripheral wall portion 135b is separated from the mounting surface of the partition wall 135, since the partition wall 135 is made of a material with high thermal conductivity, the inner peripheral wall portion 135b is also heated by the heat from the heater 138. In this way, the heater spacer 134 and the partition wall 135 are sufficiently heated over their entire area, so that it is possible to suppress the precipitation of by-products originating from the exhaust gas in the annular flow path described above. Further, the outer circumferential wall portion 135e extends upward for a long time as shown in the figure, and its upper end portion is located close to the heater 138 when the partition wall 135 is attached to the heater spacer 134. In other words, when using the partition wall 135 having such an outer peripheral wall portion 135e, it can be said that the partition wall 135 has a structure that easily receives heat from the heater 138 and is easily heated.

Note that, since the above-mentioned annular flow path is formed by the heater spacer 134 and the partition wall 135, the exhaust gas flowing through this annular flow path may be affected by the heater spacer 134 and the partition wall 135 depending on the machining state and attachment state of the heater spacer 134 and the partition wall 135, for example. There is a concern that by-products may leak toward the base portion 129 and the heat insulating spacer 137 through the space between the attachment surface of the partition wall 134 and the attachment surface of the partition wall 135 and accumulate on the base portion 129 and the like. However, in the turbo molecular pump 100 of this embodiment, when the partition wall 135 is attached to the heater spacer 134, the sealing member 136 is in close contact with the lower surface of the annular recess 134d and the upper surface of the outer edge portion 135d, so that leakage of exhaust gas is prevented. be able to.

Next, a turbo molecular pump 200, which is a second embodiment of the vacuum pump according to the present invention, will be described with reference to FIGS. 7 to 9. Note that the turbo molecular pump 200 basically includes a heater spacer 234 and a partition wall 235 in place of the heater spacer 134 and partition wall 135 of the turbo molecular pump 100 described above. Therefore, in the following, the heater spacer 234 and the partition wall 235 will be explained in detail, and the other parts will be denoted by the same reference numerals in the drawings and detailed explanation will be omitted.

The heater spacer 234 is a ring-shaped member as shown in FIGS. 7 to 9, and is made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals. . As an example, the heater spacer 234 is preferably made of a high-strength material to ensure strength at high temperatures, and in this embodiment, it is made of stainless steel in consideration of this point. A threaded spacer 131 is attached to the top of the heater spacer 234, as shown in FIG. Furthermore, mounting holes for mounting the heater 138 and the temperature sensor 139 are provided on the side surface of the heater spacer 234, and the heater 138 and the temperature sensor 139 are held by the heater spacer 234.

Further, as shown in FIG. 8, the heater spacer 234 includes a flat metal touch surface 234a extending in the horizontal direction at its lower part. Note that this metal touch surface 234a exists so as to avoid and surround a female threaded portion 234e, which will be described later. A radial positioning surface 234b that extends vertically upward is provided on the radially inner side of the metal touch surface 234a. Further, the metal touch surface 234a is provided with an annular recess 234d to which the seal member 136 is attached. As illustrated, the partition wall 235 is attached to the metal touch surface 234a, the radial positioning surface 234b, and the annular recess 234d of the heater spacer 234, and in the following description, these portions will be referred to as the heater spacer. 234 mounting surface. Further, the metal touch surface 234a is provided with a plurality of female screw portions 234e arranged at intervals in the circumferential direction.

Furthermore, the heater spacer 234 is provided with a circular through hole 234f that passes through the heater spacer 234 in the radial direction, as shown in FIG. The through hole 234f communicates with the exhaust port 133 when the turbo molecular pump 200 is assembled. In addition, the through hole 234f is located at a position (metal touch surface 234a etc.).

The partition wall 235 is a ring-shaped member as shown in FIGS. 7 to 9, and is made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals. The partition wall 235 is preferably heated by heat from the heater 138 similarly to the partition wall 135 described above, and in this embodiment, taking this point into consideration, the partition wall 235 is made of a material having a higher thermal conductivity than the heater spacer 234 (for example, aluminum). This constitutes the partition wall 235.

The partition wall 235 also includes an annular wall portion 235a in the shape of an annular plate. A cylindrical inner circumferential wall portion 235b extending upward is provided at the inner edge of the annular wall portion 235a, and a folded portion protruding radially outward is provided at the upper end of the inner circumferential wall portion 235b. 235c is provided. Further, the partition wall 235 includes an outer edge portion 235d located on the radially outer side of the annular wall portion 235a. The upper surface of the outer edge portion 235d is located below the upper surface of the annular wall portion 235a, and a step portion 235e extending in the vertical direction is provided between the outer edge portion 235d and the annular wall portion 235a. Further, the upper surface of the outer edge portion 235d is a flat surface extending in the horizontal direction. Hereinafter, the upper surface of the outer edge portion 235d will be referred to as a metal touch surface 235f. Note that the partition wall 235 is attached to a portion of the heater spacer 234 from the metal touch surface 235f to the stepped portion 235e as shown in the figure, and in the following description, the portion from the metal touch surface 235f to the stepped portion 235e will be referred to as This is referred to as the mounting surface of the partition wall 235. Note that this metal touch surface 235f exists so as to avoid and surround a bolt through hole 235g, which will be described later.

The outer edge portion 235d is provided with a plurality of bolt holes 235g that are arranged at intervals in the circumferential direction and penetrate the outer edge portion 235d in the vertical direction. The bolt through hole 235g is provided at a position corresponding to the female threaded portion 234e. Then, with the mounting surface of the heater spacer 234 and the mounting surface of the partition wall 235 facing each other, the bolt 140 is inserted into the bolt through hole 235g and screwed into the female threaded portion 234e, thereby attaching the partition wall 235 to the heater spacer 235. It can be attached to.

In the turbo molecular pump 200 configured with such members, when the partition wall 235 is attached to the heater spacer 234 with the bolts 140, the seal member 136 is in close contact with the lower surface of the annular recess 234d and the upper surface of the outer edge portion 235d. Furthermore, when the partition wall 235 is attached to the heater spacer 234, the radial positioning surface 234b and the side surface of the stepped portion 235e contact, and the metal touch surface 234a and the metal touch surface 235f contact, so that the partition wall 235 is attached to the heater spacer 234. It is positioned in the radial direction, and also in the vertical direction.

When the partition wall 235 is attached to the heater spacer 234, the lower part of the threaded spacer 131 and the cylindrical part 102d is defined by the threaded spacer 131, the heater spacer 234, and the partition wall 235, and the threaded spacer 131 and the cylindrical part 102d An annular flow path is formed that communicates with the pump flow path between the holes and the through hole 234f. Further, the folded portion 235c of the partition wall 235 is located directly below the cylindrical portion 102d, and a gap is provided between the upper surface of the folded portion 235c and the lower surface of the cylindrical portion 102d. Note that this gap functions as a non-contact seal structure, similar to the gap provided between the folded portion 135c and the cylindrical portion 102d shown in FIG.

The partition wall 235 attached to the heater spacer 234 with bolts 140 is thermally connected to the heater spacer 234. Further, the partition wall 235 is made of a material with high thermal conductivity. Therefore, the inner peripheral wall portion 235b that is separated from the mounting surface of the partition wall 235 is also heated by the heat from the heater 138 attached to the heater spacer 234. In this way, the heater spacer 234 and the partition wall 235 are sufficiently heated over the entire area, so that it is possible to suppress the precipitation of by-products derived from the exhaust gas in the annular flow path described above.

The above-mentioned annular flow path is formed by the heater spacer 234 and the partition wall 235. Therefore, depending on the processing and attachment conditions of the heater spacer 234 and the partition wall 235, the exhaust gas flowing through the annular flow path may pass between the mounting surface of the heater spacer 234 and the partition wall 235 and reach the base portion 129 or the heat insulating spacer 137. There is a concern that by-products may leak toward the base portion 129 and the like and may be deposited on the base portion 129 and the like. However, in the turbo molecular pump 200 of this embodiment, when the partition wall 235 is attached to the heater spacer 234, the sealing member 136 is in close contact with the lower surface of the annular recess 234d and the upper surface of the outer edge 235d, thereby preventing leakage of exhaust gas. be able to. Further, in this embodiment, the metal touch surface 234a and the metal touch surface 235f are in contact with each other on the upstream side of the seal member 136, thereby suppressing passage of exhaust gas. That is, since the amount of exhaust gas exposed to the seal member 136 can be sufficiently suppressed by the metal touch surface 234a and the metal touch surface 235f, the performance of the seal member 136 can be maintained even when exhausting gas that may lead to deterioration of the seal member 136. can be maintained. In particular, in this embodiment, since the position where the bolt 140 tightens the heater spacer 234 and the partition wall 235 is the position where the metal touch surface 234a and the metal touch surface 235f are provided, the metal touch surface 234a and the metal touch surface 235f are brought closer together. come into contact with. Moreover, since the metal touch surface 234a and the metal touch surface 235f exist so as to surround the female threaded portion 234e and the bolt through hole 235g, leakage of exhaust gas through the bolt through hole 235g can also be prevented. Therefore, deterioration of the seal member 136 due to exhaust gas can be further suppressed.

By the way, in the turbo molecular pump 100 described above, the through hole 134f communicating with the exhaust port 133 extends from the metal touch surface 134a, the radial positioning surface 134b, and the flank surface 134c, as shown in FIGS. 6(a) and 6(b). It is located at a position that overlaps the area of That is, since the exhaust gas that passes through the through hole 134f and is discharged from the exhaust port 133 flows near the mounting surface between the heater spacer 134 and the partition wall 135, there is a risk that the exhaust gas may enter the mounting surface. On the other hand, the through hole 234f of the turbo molecular pump 200 is located at a position offset from the area extending from the metal touch surface 234a, the radial positioning surface 234b, and the annular recess 234d, as shown in FIGS. 9(a) and 9(b). It is provided. That is, when the exhaust gas passes through the through hole 234f and is discharged from the exhaust port 133, it does not flow near the mounting surface between the heater spacer 234 and the partition wall 235, so it is possible to suppress the exhaust gas from entering from the mounting surface. can.

Although one embodiment of the present invention has been described above, the present invention is not limited to such specific embodiment, and unless specifically limited by the above explanation, the gist of the present invention described in the claims Various modifications, changes, and combinations are possible within the range. Furthermore, the effects of the embodiments described above are merely examples of effects resulting from the present invention, and do not mean that the effects of the present invention are limited to the above effects.

For example, in the stator in the embodiment described above, the threaded spacer 131 is a separate member from the

heater spacers

134 and 234, but a member that integrates the threaded spacer and the heater spacer may also be used. Further, the position where the bolt 140 is provided is not limited to the position where the

metal touch surfaces

134a, 234a and the

metal touch surfaces

135f, 235f are provided, but may be in the vicinity of the

metal touch surfaces

134a, 234a and the

metal touch surfaces

135f, 235f.

100, 200: Turbo molecular pump (vacuum pump)
103: Rotating body (rotor)
113: Rotor shaft (rotating shaft)
122: Stator column (accommodating part)
123: Fixed wing 125: Fixed wing spacer 127: Outer cylinder 129: Base portion 131: Spacer with screw 133: Exhaust port 134, 234:

Heater spacer

134a, 234a:

Metal touch surface

134f, 234f: Through hole 135, 235:

Partition wall

135b, 235b: Inner

peripheral wall portions

135c, 235c: Folded

portions

135f, 235f: Metal touch surface 136: Seal member 137: Heat insulating spacer 138: Heater (heating means)
140: Bolt

Claims

an exterior body having an exhaust port;
an accommodating section that accommodates an electrical component and is disposed inside the exterior body;
a rotating shaft rotatably supported inside the exterior body and rotated by the electrical component;
a rotor disposed outside the housing section and fixed to the rotating shaft;
a stator disposed on the outer peripheral side of the rotor;
a pump flow path provided between the outer peripheral surface of the rotor and the inner peripheral surface of the stator, through which gas flows;
a partition wall attached to the stator and defining a flow path for the gas from the outlet of the pump flow path to the exhaust port;
a heating means for heating the stator and the partition wall;
A vacuum pump characterized in that a sealing member for suppressing the intrusion of the gas is provided on a mounting surface between the stator and the partition wall.
2. The vacuum pump according to claim 1, wherein the mounting surface has a metal touch surface on the upstream side of the gas with respect to the sealing member, where the stator and the partition wall come into contact.
The vacuum pump according to claim 1, wherein the stator and the partition wall are made of different materials.
The vacuum pump according to claim 3, wherein the partition wall is formed of a material having higher thermal conductivity than the stator.
The vacuum pump according to claim 1, wherein a non-contact seal structure for suppressing the flow of the gas into the storage portion is provided on at least a part of the opposing surfaces where the rotor and the partition wall face each other. .
The vacuum pump according to claim 1, wherein the partition wall is fixed to the stator from the axial direction of the rotating shaft with bolts.
The stator has a through hole connected to the exhaust port,
The vacuum pump according to claim 1, wherein the mounting surface is provided at a position offset from the through hole with respect to the axial direction of the rotating shaft.