Vacuum pump

Abstract

Provided is a vacuum pump capable of more reliably preventing a malfunction in which exhaust gas leaks from a space between a partition wall and a portion to which the partition wall is attached. A vacuum pump (100) is provided with: an exterior body having an exhaust port (133); a rotating shaft (113) which is rotatably supported on the inside of the exterior body and which rotates by means of the electric fitting part; a rotor (103) which is disposed on the outside of the housing part (122) and is fixed to the rotating shaft (113); a stator disposed on the outer peripheral side of the rotor (103); a pump flow path, which is provided between the outer peripheral surface of the rotor (103) and the inner peripheral surface of the stator, and in which a gas flows; a partition wall (135) attached to the stator and defining a gas flow path from an outlet of the pump flow path to an exhaust port (133); and a heating mechanism (138) that heats the stator and the partition wall (135). A seal member (136) for suppressing the intrusion of gas is provided on the mounting surface of the stator and the partition wall (135).

Description

Technical Field

[0001] The present invention relates to a vacuum pump. Background Art

[0002] In the exhaust process in the vacuum chamber of the semiconductor manufacturing equipment, a vacuum pump such as a turbomolecular pump is used. In the semiconductor manufacturing process, there are processes in which various process gases are applied to the semiconductor substrate, and the vacuum pump is used not only to evacuate the chamber of the semiconductor manufacturing equipment, but also to exhaust the process gas from the chamber.

[0003] Such process gas solidifies and precipitates as a by-product when the pressure and temperature relationship shown by the vapor pressure curve changes from the gas phase to the solid phase. If such by-products accumulate in the vacuum pump, the flow path of the exhausted gas may be narrowed and the compression performance and exhaust performance of the vacuum pump may be reduced. For example, the base portion constituting the outer body of the vacuum pump and the housing portion (stator column) for electrical components such as electromagnets and motors that drive the rotor to rotate are at a low temperature, so if the exhaust gas contacts them, the by-products will accumulate.

[0004] In order to solve such a problem, measures have been taken in the past to prevent the exhaust gas from directly contacting the base part, etc. by covering at least a part of the base part, etc. with a partition wall. For example, in Patent Document 1, a partition wall (a heat insulating wall in Patent Document 1) is provided on the downstream side of the thread groove pump part of the vacuum pump, and the stator column and at least a part of the base part, which are the low temperature part, are covered by the partition wall to suppress the accumulation of by-products on the base part, etc.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent document 1: International Publication No. 2021 / 090738. Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] However, the partition wall of Patent Document 1 is Figure 4 As shown in FIG. 1 , the partition wall is fixed to the thread groove stator by bolts, for example. At this time, the partition wall is basically in close contact with the thread groove stator by tightening the bolts, but the mounting surfaces of the two may not be in sufficient contact with each other due to deviations in processing parts. In such a case, exhaust gas may leak from between the partition wall and the mounting surface of the thread groove stator, resulting in accumulation of byproducts on the base portion, etc.

[0010] In view of such a problem, an object of the present invention is to provide a vacuum pump capable of more reliably preventing the inconvenience of exhaust gas leaking from between a partition wall and a portion where the partition wall is mounted.

[0011] Means for solving technical problems

[0012] The vacuum pump of the present invention is characterized in that it comprises: an outer body having an exhaust port; a housing portion that houses an electrical component and is arranged on the inner side of the outer body; a rotating shaft that is rotatably supported on the inner side of the outer body and rotates with the aid of the electrical component; a rotor that is arranged on the outer side of the housing portion and fixed to the rotating shaft; a stator that is arranged on the outer peripheral side of the rotor; a pump flow path that is provided between the outer peripheral surface of the rotor and the inner peripheral surface of the stator, through which gas flows; a partition wall that is installed on the stator and defines the flow path of the gas from the outlet of the pump flow path to the exhaust port; and a heating mechanism that heats the stator and the partition wall; and a sealing component that suppresses the intrusion of the gas is provided on the mounting surfaces of the stator and the partition wall.

[0013] Such a vacuum pump preferably has a metal contact surface where the stator contacts the partition wall on the upstream side of the gas with respect to the sealing member in the mounting surface.

[0014] Furthermore, it is preferable that the stator and the partition wall are formed of materials different from each other.

[0015] Furthermore, it is preferable that the partition wall is formed of a material having a higher thermal conductivity than that of the stator.

[0016] Furthermore, it is preferable that a non-contact seal structure for suppressing inflow of the gas into the accommodation portion is provided on at least a portion of a facing surface of the rotor and the partition wall.

[0017] Furthermore, it is preferable that the partition wall is fixed to the stator by bolts in the axial direction of the rotating shaft.

[0018] Furthermore, it is preferred that 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.

[0019] Effects of the Invention

[0020] The vacuum pump of the present invention has a structure in which a partition wall is installed on the outer peripheral side of a rotor, and a sealing component for suppressing the intrusion of gas is provided on the mounting surface between the stator and the partition wall. That is, even if a gap of a degree of gas leakage is generated when the stator and the partition wall are mounted, for example, due to deviation in machining of the stator and the partition wall, the sealing component can more reliably prevent the unfavorable situation of gas leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a longitudinal sectional view schematically showing a first embodiment of the vacuum pump according to the present invention.

[0022] Figure 2 yes Figure 1 The circuit diagram of the vacuum pump amplifier circuit is shown.

[0023] Figure 3 This is a timing chart showing control when the current command value is larger than the detected value.

[0024] Figure 4 This is a timing chart showing control when the current command value is smaller than the detected value.

[0025] Figure 5 about Figure 1 The vacuum pump shown, (a) is a partial enlarged view of part A, and (b) is a partial enlarged view of part B.

[0026] Figure 6 about Figure 1 The heater spacer and the partition wall shown are: (a) is a perspective view showing a state where the heater spacer and the partition wall are combined; (b) is a perspective view of the heater spacer; and (c) is a perspective view of the partition wall.

[0027] Figure 7 This is a longitudinal sectional view schematically showing a second embodiment of the vacuum pump according to the present invention.

[0028] Figure 8 about Figure 7 The vacuum pump shown, (a) is a partial enlarged view of part C, (b) is a partial enlarged view of part D.

[0029] Fig. 9 about Figure 7 The heater spacer and the partition wall shown are: (a) is a perspective view showing a state where the heater spacer and the partition wall are combined; (b) is a perspective view of the heater spacer; and (c) is a perspective view of the partition wall. DETAILED DESCRIPTION

[0030] Below, while referring to the attached Figure 1 A turbomolecular pump as one embodiment of the vacuum pump according to the present invention will be described.

[0031] exist Figure 1 A longitudinal cross-sectional view of the turbomolecular pump 100 is shown in FIG. Figure 1In the turbomolecular pump 100, an air inlet 101 is provided at the upper end of a cylindrical outer cylinder 127 (a part of the outer casing). In addition, a rotating body 103 (rotor) rotating around a central axis CA is provided inside the outer cylinder 127. The rotating body 103 has turbine blades, i.e., a plurality of rotating wings 102 (102a, 102b, 102c...) radially and in multiple layers on the periphery for sucking and exhausting gas. A rotor shaft 113 (rotating shaft) is installed at the center of the rotating body 103, and the rotor shaft 113 is suspended and supported in the air by, for example, a 5-axis controlled magnetic bearing and is position-controlled. The rotating body 103 is generally made of metal such as aluminum or aluminum alloy.

[0032] The upper radial electromagnet 104 has four electromagnets arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 107 are provided close to the upper radial electromagnet 104 and corresponding to each of the upper radial electromagnets 104. The upper radial sensor 107 uses, for example, an inductance sensor having a conductive winding, an eddy current sensor, etc., and detects the position of the rotor shaft 113 based on the change in the inductance of the conductive winding that changes corresponding to the position of the rotor shaft 113. The upper radial sensor 107 is configured to detect the radial displacement of the rotor shaft 113, that is, the rotating body 103 fixed thereto, and transmit it to a control device (not shown).

[0033] In the 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. Figure 2 The amplifier circuit 150 (described later) controls the excitation of the upper radial electromagnet 104 based on the excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113 .

[0034] The rotor shaft 113 is formed 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. In addition, 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 the radial position of the lower side of the rotor shaft 113 is adjusted in the same manner as the radial position of the upper side.

[0035] Furthermore, the axial electromagnets 106A and 106B are arranged to sandwich 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 is configured to send its axial position signal to the above-mentioned control device.

[0036] Moreover, in the above-mentioned control device, for example, a compensation circuit with a PID adjustment function generates respective excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 performs excitation control on the axial electromagnet 106A and the axial electromagnet 106B respectively based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by means of magnetic force, and the axial electromagnet 106B attracts the metal disk 111 downward, and the axial position of the rotor shaft 113 is adjusted.

[0037] In this way, the control device appropriately adjusts the magnetic force of the axial electromagnets 106A and 106B acting on the metal disk 111, so that the rotor shaft 113 is magnetically suspended in the axial direction and is spatially held without contact. In addition, the amplifier circuit 150 for controlling the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

[0038] On the other hand, the motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround the rotor shaft 113. Each magnetic pole is controlled by the control device so as to drive the rotor shaft 113 to rotate via electromagnetic force acting between the magnetic poles and the rotor shaft 113. In addition, a rotation speed sensor such as a Hall element, a resolver, an encoder, etc. (not shown) is installed in the motor 121, and the rotation speed of the rotor shaft 113 is detected based on the detection signal of the rotation speed sensor.

[0039] Furthermore, for example, a phase sensor (not shown) is mounted near the lower radial sensor 108 to detect the rotation phase of the rotor shaft 113. In the control device, the position of the magnetic pole is detected using the detection signal of the phase sensor and the rotation speed sensor.

[0040] A plurality of fixed wings 123 (123a, 123b, 123c, ...) are provided on the inner circumference side of the outer cylinder 127 and the outer circumference side of the rotating body 103 with a slight gap between them and the rotating wings 102 (102a, 102b, 102c, ...). The rotating wings 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 transfer exhaust gas molecules downward by collision. The fixed wings 123 (123a, 123b, 123c, ...) are made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components.

[0041] In addition, the fixed blades 123 are also formed to be inclined 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 layers of the rotary blades 102 toward the inner side of the outer cylinder 127. In addition, the outer peripheral ends of the fixed blades 123 are supported in a state of being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, ...).

[0042] The fixed wing spacer 125 is an annular member, for example, made of a 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. A base portion 129 (a part of the outer body) is provided at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129 and communicated with the outside. The exhaust gas that enters the air intake port 101 from the chamber (vacuum chamber) side and is transferred to the interior of the turbomolecular pump 100 is transported to the exhaust port 133 on the downstream side.

[0043] A threaded spacer 131, a heater spacer 134, a partition wall 135, a sealing member 136, and a heat insulating spacer 137 are provided between the lower portion of the fixed wing spacer 125 and the base portion 129. The fixed wing 123, the fixed wing spacer 125, the threaded spacer 131, and the heater spacer 134 are components constituting a part of the stator. Details of the heater spacer 134, the partition wall 135, the sealing member 136, and the heat insulating spacer 137 will be described later.

[0044] The threaded spacer 131 is a cylindrical component made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals as components, and has a plurality of spiral thread grooves 131a engraved on its inner circumference. The spiral direction of the thread groove 131a is the direction in which the molecules of the exhaust gas are transferred to the exhaust port 133 side when the molecules move in the rotation direction of the rotating body 103. A cylindrical portion 102d is suspended from the lowermost portion of the rotating body 103 that is connected to the rotating wings 102 (102a, 102b, 102c, ...). The outer circumference of the cylindrical portion 102d is cylindrical and extends toward the inner circumference of the threaded spacer 131, and is close to the inner circumference of the threaded spacer 131 with a predetermined gap therebetween. The threaded spacer 131 and the cylindrical portion 102d function as a thread groove pump unit, and the exhaust gas transferred to the thread groove 131a by the rotary blade 102 and the fixed blade 123 is guided by the thread groove 131a and sent to the exhaust port 133. The function as a thread groove pump unit can be arbitrarily provided according to the application of the turbomolecular pump 100.

[0045] The base 129 is a disc-shaped component constituting the base of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, stainless steel, etc. The base 129 physically holds the turbomolecular pump 100 and also serves as a heat conduction path, so it is desirable to use a metal such as iron, aluminum, copper, etc. that has rigidity and high thermal conductivity.

[0046] In such a structure, when the rotary blade 102 is driven to rotate together with the rotor shaft 113 by the motor 121, the exhaust gas is sucked from the chamber through the air inlet 101 by the action of the rotary blade 102 and the fixed blade 123. The rotation speed of the rotary blade 102 is generally 20000rpm to 90000rpm, and the circumferential speed at the end of the rotary blade 102 reaches 200m / s to 400m / s. The exhaust gas sucked from the air inlet 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 is transferred to the exhaust port 133 through the flow path defined by the threaded spacer 131, the heater spacer 134 and the partition wall 135. At this time, the temperature of the rotary blade 102 rises due to frictional heat generated when the exhaust gas contacts the rotary blade 102, conduction of heat generated by the motor 121, etc., but this heat is transferred to the fixed blade 123 side by radiation or conduction by gas molecules of the exhaust gas.

[0047] The fixed blade spacers 125 are joined to each other at the outer circumference, and transfer heat received by the fixed blades 123 from the rotary blades 102 , friction heat generated when exhaust gas contacts the fixed blades 123 , and the like to the outer cylinder 127 .

[0048] In the above description, the threaded spacer 131 is arranged on the outer periphery of the cylindrical portion 102d of the rotating body 103, and the thread groove 131a is engraved on the inner peripheral surface of the threaded spacer 131. However, there is also a case where the thread groove is engraved on the outer peripheral surface of the cylindrical portion 102d, and a spacer having a cylindrical inner peripheral surface is arranged around it.

[0049] In addition, depending on the purpose of the turbomolecular pump 100, there is also the following situation: the electrical equipment part is covered with a stator column 122 (housing part), and the inside of the stator column 122 is maintained at a predetermined pressure by means of a purge gas so that the gas sucked from the air intake port 101 does not invade the electrical equipment part. The electrical equipment part is composed of an upper radial electromagnet 104, an upper radial sensor 107, a motor 121, a lower radial electromagnet 105, a lower radial sensor 108, axial electromagnets 106A, 106B, an axial sensor 109, etc.

[0050] The base portion 129 of the present embodiment is provided with a purge port 115, and a purge gas is introduced through the purge port 115. The introduced purge gas passes through the gaps between the protection bearing 120 and the rotor shaft 113, between the rotor and the stator of the motor 121, and between the stator column 122 and the inner circumferential cylindrical portion of the rotor blade 102, and is sent to the exhaust port 133.

[0051] Here, the turbomolecular pump 100 requires the determination of the model and the control based on the inherent parameters (e.g., the characteristics corresponding to the model) that are adjusted respectively. In order to save the control parameters, the turbomolecular pump 100 is equipped with an electronic circuit unit (not shown) in its main body. The electronic circuit unit is composed of semiconductor memory such as EEP-ROM and electronic parts such as semiconductor elements for accessing it, and substrates for mounting them. The electronic circuit unit is accommodated in the lower part of the base 129 constituting the lower part of the turbomolecular pump 100, such as the lower part of the rotation speed sensor not shown near the center, and is closed by an airtight bottom cover 145.

[0052] In addition, in the semiconductor manufacturing process, among the process gases introduced into the chamber, there is a process gas having a property of becoming solid if its pressure becomes higher than a predetermined value or its temperature becomes lower than a predetermined value. Inside the turbomolecular pump 100, the pressure of the exhaust gas is the lowest at the air intake port 101 and the highest at the exhaust port 133. While the process gas is being transferred from the air intake port 101 to the exhaust port 133, if its pressure becomes higher than a predetermined value or its temperature becomes lower than a predetermined value, the process gas becomes solid and adheres to and accumulates inside the turbomolecular pump 100.

[0053] For example, SiCl is used as a process gas in an Al etching device. 4 According to the vapor pressure curve, in low vacuum (760[torr]~10 -2 [torr]) and low temperature (about 20[℃]), the solid product (such as AlCl 3 ) are precipitated and deposited inside the turbomolecular pump 100. Therefore, if the precipitates of the process gas are deposited inside the turbomolecular pump 100, the deposits narrow the pump flow path and cause the performance of the turbomolecular pump 100 to decrease. In addition, the aforementioned products are in a state where they are easily solidified and deposited in the high-pressure parts near the exhaust port 133 and the threaded spacer 131.

[0054] Therefore, in order to solve this problem, a heater not shown in the figure and an annular water-cooling pipe are wound around the outer periphery of the base 129, etc., and a temperature sensor not shown in the figure (such as a thermistor) is embedded in the base 129. Based on the signal of the temperature sensor, the heating of the heater and the cooling by the water-cooling pipe are controlled (hereinafter referred to as TMS. TMS; Temperature Management System) to maintain the temperature of the base 129 at a certain high temperature (set temperature). The turbomolecular pump 100 of this embodiment has a heater 138 (heating mechanism) and a temperature sensor 139 installed on the heater spacer 134 for performing TMS.

[0055] Next, the amplification circuit 150 for controlling the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described with respect to the turbomolecular pump 100 configured as described above. Figure 2 A circuit diagram of the amplifier circuit 150 is shown in FIG.

[0056] exist Figure 2 In the embodiment, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 and the like is connected to the positive electrode 171a of the power source 171 via the transistor 161, and the other end is connected to the negative electrode 171b of the power source 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 the drain.

[0057] At this time, the cathode terminal 161a of the diode of transistor 161 is connected to the positive electrode 171a, and the anode terminal 161b is connected to one end of the electromagnet winding 151. In addition, the cathode terminal 162a of the diode of transistor 162 is connected to the current detection circuit 181, and the anode terminal 162b is connected to the negative electrode 171b.

[0058] On the other hand, the cathode terminal 165a of the current regeneration diode 165 is connected to one end of the electromagnet winding 151, and the anode terminal 165b thereof is connected to the negative electrode 171b. Similarly, the cathode terminal 166a of the current regeneration diode 166 is connected to the positive electrode 171a, and the anode terminal 166b thereof is connected to the other end of the electromagnet winding 151 via the current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall sensor type current sensor and a resistor element.

[0059] Therefore, when the magnetic bearing is controlled by five axes and there are ten electromagnets 104, 105, 106A, and 106B in total, the same amplifier circuit 150 is configured for each electromagnet, and ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0060] Furthermore, the amplification control circuit 191 is constituted by, for example, a digital signal processor unit (hereinafter referred to as a DSP unit) of the control device (not shown), and switches the transistors 161 and 162 on and off.

[0061] The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (the signal reflecting the current value is referred to as the current detection signal 191c) with the predetermined current command value. Then, based on the comparison result, the size of the pulse width (pulse width time Tp1, Tp2) generated in one cycle of PWM control, that is, the control cycle Ts is determined. As a result, the gate drive signals 191a, 191b having the pulse width are output from the amplifier control circuit 191 to the gate terminals of the transistors 161, 162.

[0062] In addition, when the rotation speed of the rotating body 103 passes through the resonance point during the acceleration operation, when interference occurs during the constant speed operation, etc., it is necessary to control the position of the rotating body 103 at high speed and with strong force. Therefore, a high voltage of about 50V, for example, is used as the power supply 171 so that a sharp increase (or decrease) in the current flowing in the electromagnet winding 151 can be achieved. In addition, between the positive electrode 171a and the negative electrode 171b of the power supply 171, a capacitor (not shown) is usually connected for the purpose of stabilizing the power supply 171.

[0063] 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 transistors 161 and 162 are turned off, the electromagnet current iL decreases.

[0064] In addition, if one of the transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is maintained. Moreover, by making the flywheel current flow through the amplifier circuit 150 in this way, the hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the circuit as a whole can be suppressed to a low level. In addition, by controlling the transistors 161 and 162 in this way, high-frequency noise such as harmonics generated in the turbomolecular pump 100 can be reduced. Furthermore, by measuring the flywheel current with the current detection circuit 181, the electromagnet current iL flowing in the electromagnet winding 151 can be detected.

[0065] That is, when the detected current value is smaller than the current command value, Figure 3 As shown, both transistors 161 and 162 are turned on only once for a time corresponding to the pulse width time Tp1 in the control cycle Ts (e.g., 100 μs). 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.

[0066] On the other hand, when the detected current value is larger than the current command value, Figure 4 As shown, both transistors 161 and 162 are turned off only once in the control cycle Ts for a time period corresponding to the pulse width time Tp2. Therefore, the electromagnet current iL during this period decreases toward the 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.

[0067] In either case, after the pulse width time Tp1 or Tp2 has elapsed, one of the transistors 161 and 162 is turned on. Therefore, during this period, a current continues to flow through the amplifier circuit 150.

[0068] Next, the heater spacer 134 , the partition wall 135 , the sealing member 136 , and the heat insulating spacer 137 described above will be described in detail.

[0069] The heater spacer 134 is as Figure 1 , Figure 5 , Figure 6 As shown in the figure, the heater spacer 134 is annular as a whole and is made of metal such as aluminum, copper, stainless steel, iron or alloys containing these metals as components. As an example, the heater spacer 134 is preferably made of a high-strength material in order to ensure strength at high temperatures. In this embodiment, it is made of stainless steel in consideration of this point. As shown in the figure, a threaded spacer 131 is installed on the upper part of the heater spacer 134. In addition, a mounting hole for mounting a heater 138 and a temperature sensor 139 is provided on the side of the heater spacer 134, and the heater 138 and the temperature sensor 139 are held on the heater spacer 134.

[0070] In addition, if Figure 5As shown in the figure, the heater spacer 134 includes a flat metal contact surface 134a extending horizontally at the lower part of the radial inner side, a radial positioning surface 134b extending vertically downward from the radial outer side of the metal contact surface 134a, and a retreat surface 134c having an inner diameter larger than that of the radial positioning surface 134b and located below the radial positioning surface 134b. Furthermore, an annular recess 134d for mounting a sealing member 136 is provided on the lower surface of the heater spacer 134. In addition, as shown in the figure, a partition wall 135 is mounted on the portion of the heater spacer 134 involving the metal contact surface 134a, the radial positioning surface 134b, the retreat surface 134c and the annular recess 134d, and these portions are referred to as the mounting surface of the heater spacer 134 in the following description. A plurality of female threaded portions 134e arranged at intervals in the circumferential direction are provided on the metal contact surface 134a.

[0071] Furthermore, the heater spacer 134 is as shown in FIG. Figure 6 (a) Figure 6 As shown in (b), a circular through hole 134f is provided which penetrates the heater spacer 134 in the radial direction. The through hole 134f is connected to the exhaust port 133 when assembled into the turbomolecular pump 100. In addition, the through hole 134f is provided at a position overlapping with the metal contact surface 134a, the radial positioning surface 134b and the retreat surface 134c with respect to the axial direction (the direction along the central axis CA) of the heater spacer 134.

[0072] The partition wall 135 is as follows Figure 1 , Figure 5 , Figure 6 As shown, the whole is annular and is made of metal such as aluminum, copper, stainless steel, iron, or alloys containing these metals. The partition wall 135 is preferably heated by heat from a heater 138 mounted on the heater spacer 134 as described later. In this embodiment, the partition wall 135 is made of a material (e.g., aluminum) having a higher thermal conductivity than the heater spacer 134 in consideration of this point.

[0073] In addition, the partition wall 135 of this embodiment has an annular wall portion 135a in the shape of an annular plate. A cylindrical inner peripheral wall portion 135b extending upward is provided at the inner edge of the annular wall portion 135a, and a folded portion 135c protruding radially outward is provided at the upper end of the inner peripheral wall portion 135b. Figure 6(Omitted in the figure). In addition, the partition wall 135 has a cylindrical outer peripheral wall portion 135e extending upward from a portion located radially inward of 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 is referred to as the metal contact surface 135f. In addition, the partition wall 135 is installed on the portion of the heater spacer 134 involving the outer edge portion 135d, the outer peripheral wall portion 135e and the metal contact surface 135f as shown in the figure. In the following description, the portion involving the outer edge portion 135d, the outer peripheral wall portion 135e and the metal contact surface 135f is referred to as the installation surface of the partition wall 135.

[0074] The outer peripheral wall portion 135e is provided with a plurality of bolt through holes 135g which are arranged at intervals in the circumferential direction and penetrate the outer peripheral wall portion 135e in the vertical direction. The bolt through holes 135g are provided at positions corresponding to the female threaded portion 134e. In addition, the partition wall 135 can be mounted to the heater spacer 134 by inserting the bolts 140 into the bolt through holes 135g and threading them into the female threaded portion 134e in a state where the mounting surface of the heater spacer 134 faces the mounting surface of the partition wall 135.

[0075] Furthermore, the partition wall 135 is as Figure 6 As shown in (c), a semicircular notch 135h is provided which penetrates the outer peripheral wall 135e in the radial direction. Figure 6 As shown in (a), when the partition wall 135 is attached to the heater spacer 134, it is combined with the through hole 134f to form a single hole.

[0076] The sealing member 136 is formed into an annular shape from an elastic material (nitrile rubber, fluororubber, silicone rubber, etc.), and has a function of suppressing the intrusion of gas from between the closely contacting component and the sealing member 136 when in close contact with the component. The sealing member 136 of this embodiment is an O-ring.

[0077] The heat insulating spacer 137 is a ring-shaped member as a whole, and is made of a material with low thermal conductivity (heat is not easily transferred). The material constituting the heat insulating spacer 137 is, for example, stainless steel. As shown in the figure, the heat insulating spacer 137 is sandwiched between the base portion 129 and the heater spacer 134, and the base portion 129 and the heater spacer 134 are thermally insulated.

[0078] In the turbomolecular pump 100 composed of such components, when the partition wall 135 is mounted on the heater spacer 134 by the bolt 140, 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. In addition, when the partition wall 135 is mounted on the heater spacer 134, the radial positioning surface 134b contacts the upper outer peripheral surface of the outer peripheral wall portion 135e, and the metal contact surface 134a contacts the metal contact surface 135f, so the partition wall 135 is positioned relative to the heater spacer 134 in the radial direction and is also positioned in the vertical direction. In addition, the retreat surface 134c located below the radial positioning surface 134b is larger in diameter than the inner diameter of the radial positioning surface 134b, so when the partition wall 135 is mounted on the heater spacer 134, it is basically not in contact with the outer peripheral surface of the outer peripheral wall portion 135e. That is, when forming the radial positioning surface 134 b and the escape surface 134 c , only the radial positioning surface 134 b is required to have processing accuracy, so the processing cost of the heater spacer 134 can be suppressed.

[0079] When the partition wall 135 is mounted on the heater spacer 134, an annular flow path is formed below the threaded spacer 131 and the cylindrical portion 102d, which is defined by the threaded spacer 131, the heater spacer 134, and the partition wall 135 and communicates with the through hole 134f and leads to the pump flow path between the threaded spacer 131 and the cylindrical portion 102d. In addition, the folded portion 135c of the partition wall 135 is located slightly 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. The gap is narrowed to such an extent that when the rotating body 103 rotates, the cylindrical portion 102d and the folded portion 135c do not contact each other and the gas flowing through the annular flow path does not flow into the stator column 122 through the gap, thereby functioning as a non-contact sealing structure.

[0080] In addition, the partition wall 135 mounted on the heater spacer 134 by means of the bolt 140 is thermally connected to the heater spacer 134. Therefore, the heat from the heater 138 is fully transferred from the heater spacer 134 to the partition wall 135, so that the partition wall 135 can be effectively heated. In addition, 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, since the heater spacer 134 and the partition wall 135 are fully heated throughout their entire area, the precipitation of by-products derived from the exhaust gas can be suppressed in the above-mentioned annular flow path. In addition, the outer peripheral wall portion 135e extends upwardly for a long time as shown in the figure, and when the partition wall 135 is mounted on the heater spacer 134, its upper end portion is located closer to the heater 138. That is, when the partition wall 135 including such an outer peripheral wall portion 135 e is used, it can be said that the partition wall 135 is easily heated by the heat from the heater 138 .

[0081] In addition, since the above-mentioned annular flow path is formed by the heater spacer 134 and the partition wall 135, for example, depending on the processing state and the mounting state of the heater spacer 134 and the partition wall 135, the exhaust gas flowing through the annular flow path may leak toward the base portion 129 and the heat insulating spacer 137 through the mounting surface of the heater spacer 134 and the mounting surface of the partition wall 135, and the by-products may be accumulated on the base portion 129. However, in the turbomolecular pump 100 of the present embodiment, when the partition wall 135 is mounted on the heater spacer 134, the sealing member 136 is in close contact with the lower surface of the annular recessed portion 134d and the upper surface of the outer edge portion 135d, so that the exhaust gas can be prevented from leaking.

[0082] Next, refer to Figure 7 to Figure 9 While explaining the turbomolecular pump 200 as the second embodiment of the vacuum pump according to the present invention. In addition, the turbomolecular pump 200 basically includes a heater spacer 234 and a partition wall 235 instead of the heater spacer 134 and the partition wall 135 of the turbomolecular pump 100 described above. Therefore, the heater spacer 234 and the partition wall 235 will be explained in detail below, and the same reference numerals are attached to the drawings and detailed explanations are omitted.

[0083] Heater spacer 234 such as Figure 7 to Figure 9 As shown in FIG. 1 , the heater spacer 234 is an annular member as a whole and is made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals as components. The heater spacer 234 is preferably made of a high-strength material to ensure strength at high temperatures. In this embodiment, the heater spacer 234 is made of stainless steel in consideration of this point. Figure 7The threaded spacer 131 is installed as shown. In addition, on the side of the heater spacer 234, mounting holes for mounting the heater 138 and the temperature sensor 139 are provided, and the heater 138 and the temperature sensor 139 are held on the heater spacer 234.

[0084] In addition, if Figure 8 As shown, the heater spacer 234 has a flat metal contact surface 234a extending in the horizontal direction at its lower part. In addition, the metal contact surface 234a exists in a manner of avoiding and surrounding the female thread portion 234e described later. A radial positioning surface 234b extending upward in the vertical direction is provided on the radial inner side of the metal contact surface 234a. In addition, an annular recess 234d for mounting the sealing component 136 is provided on the metal contact surface 234a. As shown in the figure, the partition wall 235 is installed on the parts of the heater spacer 234 involving the metal contact surface 234a, the radial positioning surface 234b and the annular recess 234d, and these parts are referred to as the mounting surface of the heater spacer 234 in the following description. In addition, a plurality of female thread portions 234e arranged at intervals in the circumferential direction are provided on the metal contact surface 234a.

[0085] Furthermore, the heater spacer 234 is as shown in FIG. Fig. 9 As shown in FIG. 2 , a circular through hole 234f is provided that penetrates the heater spacer 234 in the radial direction. The through hole 234f is connected to the exhaust port 133 when assembled into the turbomolecular pump 200. In addition, the through hole 234f is provided at a position deviated from the portion involving the metal contact surface 234a, the radial positioning surface 234b, and the annular recessed portion 234d with respect to the axial direction of the heater spacer 234 (the direction along the central axis CA) (a position above the metal contact surface 234a, etc.).

[0086] The partition wall 235 is as follows Figure 7 to Figure 9 As shown, the whole ring-shaped member is made of metal such as aluminum, copper, stainless steel, iron or alloys containing these metals. The partition wall 235 is preferably heated by the heat from the heater 138, similarly to the partition wall 135 described above. In this embodiment, the partition wall 235 is made of a material (e.g., aluminum) having a higher thermal conductivity than the heater spacer 234 in consideration of this point.

[0087] In addition, the partition wall 235 includes an annular wall portion 235a in the shape of an annular plate. A cylindrical inner peripheral wall portion 235b extending upward is provided at the inner edge portion of the annular wall portion 235a, and a folded portion 235c protruding radially outward is provided at the upper end portion of the inner peripheral wall portion 235b. In addition, the partition wall 235 includes an outer edge portion 235d located radially outward 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. In addition, 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 is referred to as the metal contact surface 235f. In addition, as shown in the figure, the partition wall 235 is installed at the portion from the metal contact surface 235f to the step portion 235e of the heater spacer 234. In the following description, the portion from the metal contact surface 235f to the step portion 235e is referred to as the installation surface of the partition wall 235. In addition, the metal contact surface 235f exists in a manner that avoids and surrounds the bolt through hole 235g described later.

[0088] The outer edge portion 235d is provided with a plurality of bolt through holes 235g which are arranged at intervals in the circumferential direction and penetrate the outer edge portion 235d in the vertical direction. The bolt through holes 235g are provided at positions corresponding to the female threaded portion 234e. In addition, in a state where the mounting surface of the heater spacer 234 faces the mounting surface of the partition wall 235, the partition wall 235 can be mounted to the heater spacer 234 by inserting the bolts 140 into the bolt through holes 235g and threading them into the female threaded portion 234e.

[0089] In the turbomolecular pump 200 composed of such components, when the partition wall 235 is mounted on the heater spacer 234 by the bolts 140, the sealing member 136 is in close contact with the lower surface of the annular recessed portion 234d and the upper surface of the outer edge portion 235d. In addition, when the partition wall 235 is mounted on the heater spacer 234, the radial positioning surface 234b contacts the side surface of the step portion 235e, and the metal contact surface 234a contacts the metal contact surface 235f, so that the partition wall 235 is positioned relative to the heater spacer 234 in the radial direction and also in the up-down direction.

[0090] When the partition wall 235 is installed on the heater spacer 234, an annular flow path is formed below the threaded spacer 131 and the cylindrical portion 102d, which is defined by the threaded spacer 131, the heater spacer 234, and the partition wall 235 and leads to the pump flow path between the threaded spacer 131 and the cylindrical portion 102d and communicates with the through hole 234f. In addition, the folded portion 235c of the partition wall 235 is located slightly 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. In addition, the gap is Figure 5 The gap between the folded portion 135c and the cylindrical portion 102d shown in the figure also functions as a non-contact sealing structure.

[0091] The partition wall 235 mounted on the heater spacer 234 by the bolt 140 is thermally connected to the heater spacer 234. In addition, the partition wall 235 is made of a material with high thermal conductivity. Therefore, the inner peripheral wall portion 235b of the partition wall 235 away from the mounting surface is also heated by the heat from the heater 138 mounted on the heater spacer 234. In this way, the heater spacer 234 and the partition wall 235 are fully heated throughout the entire area, so that the precipitation of by-products derived from the exhaust gas can be suppressed in the above-mentioned annular flow path.

[0092] The above-mentioned annular flow path is formed by the heater spacer 234 and the partition wall 235. Therefore, depending on the processing state and installation state of the heater spacer 234 and the partition wall 235, the exhaust gas flowing through the annular flow path may leak toward the base portion 129 and the heat insulating spacer 137 through the mounting surface of the heater spacer 234 and the mounting surface of the partition wall 235, and the by-products may accumulate on the base portion 129. However, when the partition wall 235 is mounted on the heater spacer 234, the turbomolecular pump 200 of this embodiment is in close contact with the lower surface of the annular recess 234d and the upper surface of the outer edge portion 235d, so that the leakage of the exhaust gas can be prevented. In addition, in this embodiment, on the upstream side of the sealing member 136, the metal contact surface 234a is in contact with the metal contact surface 235f, which suppresses the passage of the exhaust gas. That is, the exposure amount of the exhaust gas to the sealing member 136 can be fully suppressed by the metal contact surface 234a and the metal contact surface 235f, so the performance of the sealing member 136 can be maintained even when the gas that causes the deterioration of the sealing member 136 is discharged. In particular, in the present embodiment, the position where the heater spacer 234 and the partition wall 235 are fastened by the bolt 140 is the position where the metal contact surface 234a and the metal contact surface 235f are provided, so the metal contact surface 234a and the metal contact surface 235f are in closer contact. In addition, since the metal contact surface 234a and the metal contact surface 235f exist in a manner that surrounds the female thread portion 234e and the bolt through hole 235g, the leakage of the exhaust gas through the bolt through hole 235g can be prevented. Therefore, the deterioration of the sealing member 136 caused by the exhaust gas can be further suppressed.

[0093] In the above-mentioned turbomolecular pump 100, the through hole 134f communicating with the exhaust port 133 is as follows: Figure 6 As shown in (a) and (b), the exhaust gas is disposed at a position overlapping with the metal contact surface 134a, the radial positioning surface 134b and the retreat surface 134c. That is, the exhaust gas passing through the through hole 134f and discharged from the exhaust port 133 flows near the mounting surface of the heater spacer 134 and the partition wall 135, so there is a possibility that the exhaust gas will invade the mounting surface. In contrast, the through hole 234f of the turbomolecular pump 200 is as shown in FIG. Fig. 9 As shown in (a) and (b), the position is set at a position deviated from the position involving the metal contact surface 234a, the radial positioning surface 234b and the annular recessed portion 234d. 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 of the heater spacer 234 and the partition wall 235, so the intrusion of the exhaust gas from the mounting surface can be suppressed.

[0094] An embodiment of the present invention has been described above, but the present invention is not limited to the specific embodiment. Unless otherwise specified in the above description, various modifications / changes and combinations can be made within the scope of the gist of the present invention as described in the patent claims. In addition, the effects in the above embodiments are merely examples of the effects produced by the present invention, and do not mean that the effects brought about by the present invention are limited to the above effects.

[0095] For example, in the stator of the above-mentioned embodiment, the threaded spacer 131 is a component different from the heater spacer 134, 234, but a component in which the threaded spacer and the heater spacer are integrated may be used. In addition, the position where the bolt 140 is provided is not limited to the position where the metal contact surface 134a, 234a and the metal contact surface 135f, 235f are provided, and it may be near the metal contact surface 134a, 234a and the metal contact surface 135f, 235f.

[0096] Description of Reference Numerals

[0097] 100, 200: Turbomolecular pump (vacuum pump)

[0098] 103: Rotating body (rotor)

[0099] 113: Rotor shaft (rotating axis)

[0100] 122: stator column (housing part)

[0101] 123: Fixed wing

[0102] 125: Fixed wing spacer

[0103] 127: Outer cylinder

[0104] 129: Base

[0105] 131: Threaded spacer

[0106] 133: Exhaust port

[0107] 134, 234: Heater spacer

[0108] 134a, 234a: Metal contact surface

[0109] 134f, 234f: Through hole

[0110] 135, 235: Partition wall

[0111] 135b, 235b: Inner peripheral wall portion

[0112] 135c, 235c: Folding part

[0113] 135f, 235f: Metal contact surface

[0114] 136: Sealing parts

[0115] 137: Thermal insulation spacers

[0116] 138: Heater (heating mechanism)

[0117] 140: Bolt.

Claims

1. A vacuum pump, characterized in that: have: an outer body having an exhaust port; A housing portion for housing the electrical device and arranged inside the outer casing; A rotating shaft is rotatably supported inside the outer casing and rotated by the electrical device; A rotor is arranged outside the housing portion and fixed to the rotating shaft; A stator is arranged 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 the gas flows; a partition wall mounted on the stator and defining a flow path of the gas from the outlet of the pump flow path to the exhaust port; as well as A heating mechanism for heating the stator and the partition wall; A sealing member for suppressing the intrusion of the gas is provided on the mounting surface of the stator and the partition wall.

2. The vacuum pump according to claim 1, characterized in that The mounting surface has a metal contact surface where the stator contacts the partition wall on the upstream side of the gas relative to the sealing member.

3. The vacuum pump according to claim 1, characterized in that The stator and the partition wall are formed of materials different from each other.

4. The vacuum pump according to claim 3, characterized in that The partition wall is formed of a material having a higher thermal conductivity than the stator.

5. The vacuum pump according to claim 1, characterized in that A non-contact seal structure for suppressing inflow of the gas into the housing portion is provided at least in a portion of a facing surface of the rotor and the partition wall.

6. The vacuum pump according to claim 1, characterized in that The partition wall is fixed to the stator by bolts in the axial direction of the rotating shaft.

7. The vacuum pump according to claim 1, characterized in that The stator has a through hole connected to the exhaust port; The mounting surface is provided at a position offset from the through hole with respect to the axial direction of the rotating shaft.

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