Vacuum pump and heat insulating member used in the vacuum pump

Abstract

To provide a vacuum pump that increases rigidity and heat insulation effectiveness of a heat insulation part to facilitate management of temperatures of pump internal components as intended, and to provide a heat insulation member used for the vacuum pump.SOLUTION: A turbo molecular pump 100 with at least a cooling function includes a heat insulation material 203 disposed in a threaded spacer 131 and having a hollow structure in which cavities 204B formed along an axial direction are repeatedly provided in a circumferential direction. The cavity 204B is formed substantially into a parallelogram in view of an opening direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vacuum pump and a heat insulating member used in the vacuum pump, and more particularly to a vacuum pump that can be used in a pressure range from low vacuum to ultra-high vacuum, and a heat insulating member used in the vacuum pump. [Background technology]

[0002] When manufacturing semiconductor devices such as memories and integrated circuits, it is necessary to perform doping and etching on high-purity semiconductor substrates (wafers) in a high-vacuum chamber to avoid the effects of dust and other particles in the air, and a vacuum pump such as a turbomolecular pump is used to evacuate the chamber.

[0003] Known examples of such vacuum pumps include a cylindrical casing, a cylindrical stator that is nested and fixed within the casing and has threaded grooves, and a rotor that is supported within the stator so that it can rotate at high speed.

[0004] In vacuum pumps, depending on the gas sucked in from the intake port of the casing, the gas may change phase from gas to solid during the compression process inside the pump (inside the casing), and solidify inside the pump. As a result, solidified material may accumulate inside the pump, causing problems such as blocking the gas flow path.

[0005] As a method for solving this problem, it has been known that solidification can be prevented by heating the vacuum pump and increasing the temperature. However, if the pump is heated without understanding the internal temperature state, there is a possibility that the temperature of the parts that you do not want to heat will exceed the appropriate temperature, i.e., the pump will fall into an overheated state. Therefore, a technology is known in which a heat insulating material is placed between the parts that you want to heat and the parts that you do not want to heat, and only the parts that you want to heat are selectively heated (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-151932 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the invention described in Patent Document 1, in order to improve the insulating effect of the insulating part, it is necessary to reduce the cross-sectional area by thinning the wall thickness of the insulating part. However, reducing the cross-sectional area reduces the rigidity of the insulating part. This reduced rigidity has led to the following problems. (1) The risk of buckling increases. (2) The natural frequency decreases, causing resonance. (2) It may be deformed by external impact, causing the rotating and fixed parts to come into contact and resulting in a malfunction. (3) Distortion is likely to occur during processing, making processing difficult and increasing costs. Therefore, when these problems are taken into consideration, the heat insulating part becomes a thick and long part, which also creates space restrictions, making it difficult to achieve the necessary and sufficient heat insulating effect.

[0008] Therefore, a technical problem arises that must be solved in order to provide a vacuum pump and an insulating member for use in said vacuum pump that improves the rigidity and insulating effect of the insulating part, thereby making it easier to control the temperature of the components inside the pump as intended, and the present invention aims to solve this problem. [Means for solving the problem]

[0009] The present invention has been proposed to achieve the above object, and the invention described in claim 1 is a vacuum pump having at least one of a heating function and a cooling function, wherein the temperature-controlled parts to be heated or cooled are The screw groove pump mechanism includes at least a screw groove pump mechanism, and the screw groove pump mechanism and the base are spaced apart in an axial direction. are arranged in The aforementionedThe object of the present invention is to provide a vacuum pump which has an insulating section having a hollow structure in which a plurality of cavities formed along the axial or radial direction are repeatedly arranged in the circumferential direction, and at least some of the cavities formed along the axial direction among the plurality of cavities are formed in the shape of a parallelogram inclined in the circumferential direction when viewed from the opening direction.

[0010] With this configuration, the insulating portion, which is part of the component, has a hollow structure, which increases the moment of inertia of the insulating portion, thereby improving its rigidity. Therefore, even if the cross-sectional area of ​​the insulating portion remains the same, both the rigidity and the insulating effect are improved, making it easier to control the temperature of the components inside the vacuum pump as intended. In other words, it is possible to selectively heat or cool only the necessary components, such as the downstream flow path. Furthermore, by forming the cavity into a roughly parallelogram shape when viewed from the opening direction, the radial rigidity can be selectively reduced. Even if the internal components thermally expand, the roughly parallelogram portion deforms, mitigating the load.

[0011] A second aspect of the present invention provides the vacuum pump of the first aspect, wherein at least a part of the cavity is formed in a substantially triangular shape when viewed from the opening direction.

[0012] According to this configuration, if the hole shape of the cavity is made to be approximately triangular when viewed from the opening direction, the rigidity of the heat insulating part increases and the heat insulating part becomes easier to form, thereby reducing costs and improving the heat insulating effect.

[0013] A third aspect of the present invention provides the vacuum pump according to the first or second aspect, wherein the cavity is at least partially blocked.

[0014] According to this configuration, by blocking at least a portion of the cavity, the rigidity is further improved compared to when the cavity is a through hole.

[0015] The invention described in claim 4 provides a vacuum pump having the configuration described in any one of claims 1 to 3, further comprising a turbomolecular pump mechanism including a rotor having a plurality of rotor blades arranged in multiple stages in the axial direction and a plurality of stator blades arranged between the plurality of rotor blades, wherein the temperature-controlled component is at least one stator blade of the plurality of stator blades, and the heat-insulating portion is arranged on a support portion of the stator blade.

[0016] According to this configuration, in a turbomolecular pump mechanism including a rotor having a plurality of rotor blades arranged in multiple stages in the axial direction and a plurality of stator blades disposed between the plurality of rotor blades, a hollow heat insulating portion is provided as a spacer at the support portion of the stator blades, thereby increasing the moment of inertia of the area in the turbomolecular pump mechanism. This improves both the rigidity and heat insulating effect of the entire motor, making it easier to control the temperature of the components inside the vacuum pump as desired. As a result, it is possible to selectively heat or cool only the necessary components, such as the downstream flow path.

[0017] The invention described in claim 5 provides a vacuum pump having the configuration described in any one of claims 1 to 4, further comprising a Holweck type pump mechanism in which a thread groove is formed on at least one surface of the outer peripheral surface of a rotating cylinder and the inner peripheral surface of a fixed cylinder that face each other in the radial direction, wherein the temperature-controlled component is the fixed cylinder, and the insulating part is arranged on a support part of the fixed cylinder.

[0018] According to this configuration, in a vacuum pump equipped with a Holweck pump mechanism in which thread grooves are formed on at least one surface of the inner circumferential surface of the rotating cylinder and the outer circumferential surface of the fixed cylinder, which are radially opposed to each other, a hollow insulating section is provided as a spacer in the support section of the fixed cylinder, thereby increasing the moment of inertia of the Holweck pump mechanism. This improves both the rigidity and insulating effect of the entire pump, making it easier to control the temperature of the components inside the vacuum pump as desired. As a result, it is possible to selectively heat or cool only the necessary components, such as the downstream flow path.

[0019] The invention described in claim 6 provides a vacuum pump having the configuration described in any one of claims 1 to 5, further comprising a Sigburn type pump mechanism having a rotating disk and a fixed disk that face each other in the axial direction, and in which a spiral groove having spiral ridges and spiral valleys is formed on at least one surface of the fixed disk that faces the rotating disk, wherein the temperature-controlled part is the fixed disk, and the heat-insulating part is arranged on a support part of the fixed disk.

[0020] According to this configuration, in a vacuum pump equipped with a Sigburn pump mechanism having a rotating disk and a fixed disk facing each other in the axial direction, with a spiral groove having spiral peaks and valleys formed on at least one surface of the fixed disk facing the rotating disk, a hollow insulating section is provided as a spacer at the support portion of the fixed disk, thereby increasing the moment of inertia of the Sigburn pump mechanism. This improves both the rigidity and insulating effect of the entire pump, making it easier to control the temperature of the components inside the vacuum pump as desired. As a result, it is possible to selectively heat or cool only the necessary components, such as the downstream flow path.

[0021] The invention described in claim 7 is a heat insulating member used in a vacuum pump having at least one of a heating function and a cooling function, The screw groove pump mechanism includes at least a screw groove pump mechanism, and the screw groove pump mechanism and the base are spaced apart in an axial direction. are arranged in The aforementioned Provided is an insulating member having a hollow structure in which a plurality of cavities formed along the axial or radial direction are repeatedly arranged in the circumferential direction, and at least some of the cavities formed along the axial direction among the plurality of cavities are formed in the shape of a parallelogram inclined in the circumferential direction when viewed from the opening direction.

[0022] According to this configuration, by using a vacuum pump with an insulating member having a hollow structure formed in the axial or radial direction, the moment of inertia of the insulating section is increased, improving rigidity. This improves both the rigidity and insulating effect of the entire pump, making it easier to control the temperature of the components inside the vacuum pump as desired. As a result, it is possible to selectively heat or cool only necessary components, such as downstream flow paths. Furthermore, by forming the cavity into a roughly parallelogram shape when viewed from the opening direction, the radial rigidity can be selectively reduced, and even if the internal components thermally expand, the roughly parallelogram portion can deform, mitigating the load. [Effects of the Invention]

[0023] According to the present invention, the insulating portion, which is a part of the component, has a hollow structure, which increases the moment of inertia of the insulating portion, thereby improving its rigidity. Therefore, even if the cross-sectional area of ​​the insulating portion remains the same, both the rigidity and the insulating effect are improved, making it easier to control the temperature of the components inside the vacuum pump as desired. As a result, it is possible to selectively heat or cool only the necessary parts, such as the downstream flow path. This allows heating of the parts (locations) of the pump that are truly necessary, preventing the accumulation of reaction products. Conversely, when cooling is required, cooling of the parts (locations) of the pump that are truly necessary prevents the pump from overheating. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a vertical cross-sectional view of a turbomolecular pump shown as a first embodiment of a vacuum pump according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of an amplifier circuit in the turbomolecular pump of the first embodiment. [Figure 3] 4 is a time chart showing an example of control when a current command value detected by an amplifier circuit in the turbomolecular pump of the first embodiment is larger than a detected value. [Figure 4] 4 is a time chart showing an example of control when a current command value detected by an amplifier circuit in the turbomolecular pump of the first embodiment is smaller than a detected value. [Figure 5] 1A and 1B are enlarged views of a part of a heat insulating material in the turbomolecular pump of the first embodiment, where FIG. 1A is a plan view, FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. 1C is a cross-sectional view showing a modified example of FIG. [Figure 6] FIG. 6 is a plan view showing another modified example of the heat insulating material shown in FIG. 5. [Figure 7] 5A and 5B are diagrams illustrating the difference in rigidity between when the insulation material has a solid plate structure and when it has a hollow plate structure, where (a) is a diagram illustrating the rigidity of the solid plate structure, (b) is a diagram illustrating the rigidity of the hollow plate structure shown in FIG. 5, and (c) is a diagram illustrating the rigidity of the hollow plate structure shown in FIG. 6. [Figure 8] FIG. 2 is a vertical cross-sectional view of a turbomolecular pump shown as a second embodiment of a vacuum pump according to the present invention. [Figure 9] 10A and 10B are enlarged views of a part of a heat insulating material in the turbomolecular pump of the second embodiment, in which (a) is a plan view, (b) is a cross-sectional view taken along line BB in (a), and (c) is a cross-sectional view showing a modified example of (b). [Figure 10] FIG. 10 is a vertical cross-sectional view of a turbomolecular pump shown as a third embodiment of a vacuum pump according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] In order to achieve the object of providing a vacuum pump and an insulating member to be used in said vacuum pump, which improves the rigidity and insulating effect of the insulating part and makes it easier to control the temperature of the components inside the pump as intended, the present invention has been realized by providing a vacuum pump having at least one of a heating function or a cooling function, which is provided with an insulating part that is disposed in the temperature-controlled part to be heated or cooled and has a hollow structure formed into a cavity along the axial or radial direction. [Example]

[0026] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the following embodiment, when the number, value, amount, range, etc. of components is mentioned, the number is not limited to the specific number, and may be more or less than the specific number, unless otherwise specified or when it is clearly limited to a specific number in principle.

[0027] Furthermore, when referring to the shape or positional relationship of components, etc., it includes things that are substantially similar or approximate to those shapes, etc., unless otherwise specified or when it is clearly considered otherwise in principle.

[0028] In addition, the drawings may exaggerate characteristic parts to make the features easier to understand, and the dimensional proportions of the components may not be the same as in reality. In addition, in cross-sectional views, hatching of some components may be omitted to make the cross-sectional structure of the components easier to understand.

[0029] In the following description, expressions indicating directions such as up, down, left, and right are not absolute, but are appropriate when each part of the vacuum pump of the present invention is in the position shown, but if the position changes, they should be interpreted accordingly. Furthermore, the same symbols are used for the same elements throughout the description of the embodiments.

[0030] A longitudinal cross-sectional view of this turbomolecular pump 100 is shown in Fig. 1. In Fig. 1, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Inside the outer cylinder 127 is provided a rotor 103 having a plurality of rotors 102 (102a, 102b, 102c, ...) which are turbine blades for sucking in and exhausting gas, formed radially and in multiple stages around its periphery. A rotor shaft 113 is attached to the center of this rotor 103, and this rotor shaft 113 is levitated and supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing.

[0031] The upper radial electromagnets 104 are arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to each upper radial electromagnet 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on changes in the inductance of the conductive windings, which change according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send the detected displacement to a control device (not shown).

[0032] 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 an amplifier circuit 150 (described later) shown in Figure 2 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

[0033] 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 electromagnets 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. The lower radial electromagnets 105 and the lower radial sensors 108 are arranged in the same manner as the upper radial electromagnets 104 and the upper radial sensors 107, and adjust the radial position of the lower side of the rotor shaft 113 in the same manner as the radial position of the upper side.

[0034] Furthermore, axial electromagnets 106A and 106B are arranged above and below a circular metal disk 111 provided at the bottom of rotor shaft 113. Metal disk 111 is made of a highly magnetic permeable material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and the axial position signal is sent to the control device.

[0035] In the control device, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for each of the axial electromagnets 106A and 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of each of the axial electromagnets 106A and 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disc 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disc 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0036] In this way, the control device appropriately adjusts the magnetic forces that the axial electromagnets 106A and 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. The amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

[0037] Meanwhile, motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround rotor shaft 113. Each magnetic pole is controlled by a control device so as to rotate rotor shaft 113 via electromagnetic force acting between the magnetic pole and rotor shaft 113. Motor 121 also incorporates a rotational speed sensor (not shown), such as a Hall element, resolver, or encoder, and the rotational speed of rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

[0038] Furthermore, a phase sensor (not shown) is attached, for example, near the lower radial sensor 108, to detect the phase of rotation of the rotor shaft 113. The control device uses the detection signals from both this phase sensor and the rotational speed sensor to detect the position of the magnetic pole.

[0039] A plurality of fixed blades 123a, 123b, 123c... are arranged with a small gap between them and the rotating blades 102 (102a, 102b, 102c...). Each of the rotating blades 102 (102a, 102b, 102c...) is 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.

[0040] Similarly, the fixed blades 123 are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged in a staggered manner with the rows of rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral ends of the fixed blades 123 are supported by being inserted between a plurality of stacked rows of fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0041] The fixed vane spacer 125 is a ring-shaped member made of a metal such as aluminum, iron, stainless steel, or copper, or an alloy containing any of these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed vane spacer 125 with a small gap between them. A base 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base 129 and communicates with the outside. Exhaust gas that enters the intake port 101 from the chamber side and is transferred to the base 129 is sent to the exhaust port 133.

[0042] Furthermore, depending on the application of the turbomolecular pump 100, a threaded spacer 131 is disposed between the lower portion of the stator spacer 125 and the base portion 129. The threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing any of these metals, and has multiple spiral thread grooves 131a engraved on its inner circumferential surface. The spiral direction of the threaded grooves 131a corresponds to the direction in which exhaust gas molecules are transported toward the exhaust port 133 when they move in the rotational direction of the rotor 103. A cylindrical portion 102d hangs down from the lowest portion of the rotor 103, adjacent to the rotor blades 102 (102a, 102b, 102c, etc.). The outer circumferential surface of this 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. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blade 123 is sent to the base portion 129 while being guided by the thread groove 131a.

[0043] The base portion 129 is a disk-shaped member that forms the base of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, stainless steel, etc. The base portion 129 not only physically holds the turbomolecular pump 100, but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

[0044] In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the action of the rotor 102 and the stator 123 causes exhaust gas to be drawn from the chamber through the intake port 101. The exhaust gas drawn in through the intake port 101 passes between the rotor 102 and the stator 123 and is transferred to the base portion 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121, but this heat is transferred to the stator 123 side by radiation or conduction by gas molecules of the exhaust gas, etc.

[0045] The stator spacers 125 are joined together at their outer peripheries and transmit to the outside heat received by the stator 123 from the rotor 102 and frictional heat generated when exhaust gas comes into contact with the stator 123.

[0046] In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotor 103, and the thread groove 131a is formed on the inner periphery of the threaded spacer 131. However, conversely, there are also cases where a thread groove is formed on the outer periphery of the cylindrical portion 102d, and a spacer having a cylindrical inner periphery is disposed around the threaded spacer 131. Furthermore, depending on the application of the turbomolecular pump 100, the electrical component part may be covered by a stator column 122 to prevent gas drawn in from the intake port 101 from entering the electrical component part, which is composed of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., and the interior of this stator column 122 may be maintained at a predetermined pressure by purge gas.

[0047] In this case, piping (not shown) is provided in the base portion 129, and purge gas is introduced through this piping. The introduced purge gas is sent to the exhaust port 133 through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102.

[0048] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that have been individually adjusted and identified for the model. To store these control parameters, the turbomolecular pump 100 is provided with an electronic circuit section 141 within its body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown) near the center of a base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom lid 145.

[0049] In the semiconductor manufacturing process, some process gases introduced into a chamber have the property of solidifying when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the inlet port 101 and highest at the outlet port 133. If the pressure of the process gas exceeds a predetermined value or the temperature falls below a predetermined value while the process gas is being transferred from the inlet port 101 to the outlet port 133, the process gas solidifies and adheres to and accumulates inside the turbomolecular pump 100.

[0050] For example, when SiCl4 is used as the process gas in an Al etching apparatus, the vapor pressure curve shows that at low vacuum (760 [torr] to 10-2 [torr]) and low temperature (approximately 20 [°C]), solid products (e.g., AlCl3) precipitate and adhere to and accumulate inside the turbomolecular pump 100. As a result, when process gas precipitates accumulate inside the turbomolecular pump 100, these deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. Furthermore, the above-mentioned products are prone to solidification and adhesion in high-pressure areas near the exhaust port and near the threaded spacer 131.

[0051] Therefore, in order to solve this problem, conventionally, a heater (not shown) or a circular water-cooled pipe 149 is wrapped around the outer periphery of the base portion 129, etc., and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 129, and heating by the heater or cooling by the water-cooled pipe 149 or the like is controlled based on the signal from this temperature sensor to maintain the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; Temperature Management System).

[0052] Next, a description will be given of the amplifier circuit 150 that controls excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B in the turbomolecular pump 100. A circuit diagram of this amplifier circuit 150 is shown in FIG.

[0053] 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to a positive electrode 171a of a power supply 171 via a transistor 161, and the other end is connected to a negative electrode 171b of the power supply 171 via a current detection circuit 181 and a transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

[0054] At this time, the transistor 161 has a diode cathode terminal 161a connected to the positive electrode 171a and an anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has a diode cathode terminal 162a connected to the current detection circuit 181 and an anode terminal 162b connected to the negative electrode 171b.

[0055] Meanwhile, current regeneration diode 165 has its cathode terminal 165a connected to one end of electromagnet winding 151 and its anode terminal 165b connected to negative electrode 171b. Similarly, current regeneration diode 166 has its cathode terminal 166a connected to positive electrode 171a and its anode terminal 166b connected to the other end of electromagnet winding 151 via current detection circuit 181. Current detection circuit 181 is configured, for example, with a Hall sensor type current sensor or an electrical resistance element.

[0056] The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled in five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0057] Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) of the control device (not shown), and this amplifier control circuit 191 switches the transistors 161 and 162 on and off.

[0058] The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Based on the comparison result, the amplifier control circuit 191 determines the size of the pulse width (pulse width times Tp1 and Tp2) to be generated within a control cycle Ts, which is one period under PWM control. As a result, gate drive signals 191a and 191b having these pulse widths are output from the amplifier control circuit 191 to the gate terminals of the transistors 161 and 162.

[0059] It is necessary to control the position of rotor 103 at high speed and with strong force when, for example, the rotor 103 passes through a resonance point during acceleration of its rotational speed or when a disturbance occurs during constant-speed operation. For this reason, a high voltage of, for example, about 50 V is used as power supply 171 so that the current flowing through electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between positive electrode 171a and negative electrode 171b of power supply 171 to stabilize power supply 171.

[0060] In this 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.

[0061] 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 passing a flywheel current through the amplifier circuit 150 in this manner, hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Furthermore, by controlling the transistors 161 and 162 in this manner, high-frequency noise such as harmonics generated in the turbomolecular 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.

[0062] That is, when the detected current value is smaller than the current command value, both transistors 161 and 162 are turned on for a time period corresponding to pulse width time Tp1 only once in a control cycle Ts (for example, 100 μs), as shown in Fig. 9. Therefore, during this period, the electromagnet current iL 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.

[0063] On the other hand, if the detected current value is greater than the current command value, both transistors 161 and 162 are turned off for a time period corresponding to pulse width time Tp2 only once during control cycle Ts, as shown in Fig. 10. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from negative pole 171b to positive pole 171a via diodes 165 and 166.

[0064] In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, a flywheel current is maintained in the amplifier circuit 150 during this period.

[0065] As described above, inside the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the inlet 101 and highest at the outlet 133. If the pressure of the process gas increases or the temperature decreases while the process gas is being transferred from the inlet 101 to the outlet 133, the process gas solidifies and adheres to and accumulates inside the turbomolecular pump 100. To solve this problem, a heater (not shown) is wound around the outer periphery of the base 129 or the like to provide a heating function. Alternatively, a circular water-cooled pipe 149 is wound around the base 129 to provide at least one of a cooling function (a cooling function is provided in this embodiment), and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base 129. The heater heating and the cooling by the water-cooled pipe 149 are controlled (TMS) based on a signal from the temperature sensor to maintain the temperature of the base 129 at a constant high temperature (set temperature).

[0066] Therefore, in order to prevent the temperature on the turbomolecular pump mechanism 201 side or the temperature on the thread groove pump mechanism part 202 side, which is equipped with a rotor 103 having a plurality of rotor blades 102 arranged in multiple stages in the axial direction, from affecting the temperature control of the base part 129, and conversely, to prevent the temperature on the base part 129 side from being affected, an insulating material 203 is provided as an insulating part between the threaded spacer 131 and the base part 129.

[0067] The thread groove pump mechanism 202 of the turbomolecular pump 100 is configured as a Holweck type pump mechanism in which the thread groove 131a is provided on the inner peripheral surface of the threaded spacer 131, which is a fixed cylinder that faces the outer peripheral surface of the cylindrical portion 102d, which is a rotating cylinder, in the radial direction, but the thread groove 131a may also be configured to be provided on the outer peripheral surface of the cylindrical portion 102d, which is a rotating cylinder.

[0068] The heat insulating material 203 functions as a heat insulating part for blocking heat transfer between the threaded spacer 131 and the base part 129. The heat insulating material 203 is made of stainless steel and has a lower thermal conductivity than the aluminum threaded spacer 131 and the base part 129. Note that the specific material of the heat insulating material 203 may be any material as long as it has a lower thermal conductivity than either the threaded spacer 131 or the base part 129, and it is preferable that the material has a lower thermal conductivity than the aluminum threaded spacer 131 and the base part 129.

[0069] The insulating material 203 is an annular member, and as shown in Figure 1, the inner peripheral surface 203A of the insulating material 203 faces the outer peripheral surface 131B of the lower end axial support portion 131A of the threaded spacer 131, which serves as a support portion for the fixed cylinder, and the upper end surface 203B of the insulating material 203 abuts against the lower end surface 131C of the threaded spacer 131, and further the lower end surface 203C abuts against the upper surface 129A of the base portion 129, so that the insulating material 203 is sandwiched between the lower end surface 131C of the threaded spacer 131 and the upper surface 129A of the base portion 129.

[0070] As shown in FIG. 5, the heat insulating material 203 has repeated cavities 204A extending from the upper end face 203B to the lower end face 203C between the inner circumferential surface 203A and the outer circumferential surface 203D, i.e., in the thickness portion. The cavities 204A are formed in a generally triangular hole shape when viewed from the end face 203B side (opening direction), and the generally triangular cavities 204A are arranged in a regular pattern with their apexes and bases facing alternately inward (toward the inner circumferential surface 203A) and outward (toward the outer circumferential surface 203D). By forming the hole shape of the cavities 204A in a generally triangular hole shape when viewed from the opening direction (toward the end face 203B), the rigidity of the heat insulating portion (heat insulating material 203) is increased and the heat insulating portion is also easier to form. This allows for improved heat insulating effect while reducing costs. In the above example, the cavity 204A of the thermal insulation material 203 is formed as a cavity 204A that penetrates from the upper end face 203B to the lower end face 203C. However, as shown in FIG. 5(c), for example, by forming a blocking portion 203H that blocks the cavity 204A in the cavity 204 so as to block the opening on one end side (the end face 203C side) of the cavity 204A, the rigidity of the thermal insulation material 203 can be further increased compared to a structure in which the cavity 204A is a through-hole. Even in a structure in which the cavity 204A has a blocking portion 203H, at least one side is hollow, reducing the contact area, thereby reducing heat conduction at the contact points and providing thermal insulation. The blocking portion 203H may also be formed to block the middle or both ends of the cavity 204A. It may also be formed in some of the cavities 204A among multiple cavities 204A.

[0071] Furthermore, as shown in FIG. 6, the heat insulating material 203 may have cavities 204B formed between the inner peripheral surface 203A and the outer peripheral surface 203D, i.e., in the thickness portion, penetrating from the upper end surface 203B to the lower end surface 203C. The cavities 204B shown in FIG. 6 are formed in a regular pattern with two opposing sides facing inward (toward the inner peripheral surface 203A) and outward (toward the outer peripheral surface 203D). Forming the hole shape of the cavities 204B into a generally parallelogram shape as viewed from the opening direction (toward the end surface 203B) increases the rigidity of the heat insulating portion (heat insulating material 203) and also makes it easier to form the heat insulating portion. This reduces costs and improves the heat insulating effect. Furthermore, when cavity 204B is formed in a substantially parallelogram shape, the radial rigidity is selectively reduced, and even if the temperature-controlled components inside (for example, threaded spacer 131, base portion 129, etc.) thermally expand, the substantially parallelogram portion deforms, thereby alleviating the load. Note that, in the case of heat insulating material 203 shown in Fig. 6, when at least some of the cavities 204B are formed so that one end portion, a middle portion, or both end portions are blocked, the rigidity of heat insulating material 203 can be further increased compared to a structure in which cavity 204B is a through hole.

[0072] Here, the difference in rigidity between a case where the heat insulating material 203 has a hollow structure and a case where it does not have a hollow structure will be verified using Figure 7. Figure 7 shows a case where a solid plate without a cavity is used as the heat insulating material 203, and a case where a substantially triangular cavity 204A and a substantially parallelogram cavity 204B are used, where (a) is the case of the solid plate, (b) is the case of the hollow plate with the triangular cavity 204A, and (c) is the case of the hollow plate with the substantially parallelogram cavity 204B. In this verification, for the solid plate in (a), the plate thickness T was 4 mm (millimeters) and the circumferential direction (width) length L was 2.8 mm, and for the hollow plates in (b) and (c), the thickness T was 5 mm and the circumferential direction (width) length L was 2.8 mm. Furthermore, the thickness t of beams 205 separating cavities 204A in the hollow plates of (b) and (c) was 0.5 mm, and the aperture ratio was 66%.

[0073] In the case of the solid plate in FIG. 7(a), the second moment of area I of the shaded area surrounded by line 206 in FIG. 7 is expressed by equation (1) in FIG. 7, and the cross-sectional area S is expressed by equation (2).

[0074] In the case of the hollow plate of FIG. 7(b), the second moment of area I of the shaded area surrounded by line 206 in FIG. 7 is expressed by formula (3), and the cross-sectional area S is expressed by formula (4).

[0075] The case of the hollow plate in Figure 7(c) is almost the same as the case of the hollow plate in Figure 7(b), and the second moment of area I of the shaded area surrounded by line 206 in Figure 7 is approximately expressed by equation (3), and the cross-sectional area S is expressed by equation (4). Strictly speaking, the cross-sectional area of ​​the beam part is larger than in the case of the hollow plate in Figure 7(b), so the second moment is slightly larger, but here we have made an approximate calculation assuming them to be equivalent.

[0076] From this calculation, it can be seen that in the case of the hollow plates (b) and (c) in Figure 7, even though the moment of inertia I is roughly the same as in the case of the solid plate (a), the cross-sectional area S can be made less than half, so the same insulating effect can be obtained even if the length is made less than half, and if the length is made the same, twice the insulating effect can be obtained and rigidity is also improved.

[0077] Fig. 8 shows a second embodiment of the turbomolecular pump 100 relating to the vacuum pump of the present invention. The configuration of the second embodiment is such that the structure of the heat insulating material 203 is changed, but the other configuration is the same as that of Fig. 1, so the same components are given the same reference numerals and redundant explanations will be omitted.

[0078] The turbomolecular pump 100 shown in the second embodiment is also configured as a Holweck type pump mechanism, as in the first embodiment, and the thread groove pump mechanism section 202 has a thread groove 131a provided on the inner peripheral surface of a threaded spacer 131, which is a fixed cylinder that faces the outer peripheral surface of a cylindrical section 102d, which is a rotating cylinder, in the radial direction. The turbomolecular pump 100 here may also be configured so that the thread groove 131a is provided on the outer peripheral surface of the cylindrical section 102d, which is a rotating cylinder.

[0079] Furthermore, in the turbomolecular pump 100 shown in the second embodiment, as in the first embodiment, a heat insulating material 203 is provided as a heat insulating section between the threaded spacer 131 and the base portion 129 to prevent the temperature on the turbomolecular pump mechanism 201 side or the temperature on the thread groove pump mechanism portion 202 side from affecting the temperature control of the base portion 129, and conversely, to prevent the controlled temperature on the base portion 129 side from affecting the turbomolecular pump mechanism 201 side or the thread groove pump mechanism portion 202 side.

[0080] 9A and 9B are enlarged views of a part of the heat insulating material 203 in the turbo molecular pump 100 of the second embodiment, where (a) is a plan view and (b) is a cross-sectional view taken along line BB in (a). 9 is also made of, for example, stainless steel, and has a lower thermal conductivity than the aluminum threaded spacer 131 and base portion 129. The heat insulating material 203 is an annular member, and as shown in FIG. 8, the heat insulating material 203 is disposed between the lower end surface 131C of the threaded spacer 131 and the upper surface 129A of the base portion 129, with the inner peripheral surface 203A of the heat insulating material 203 facing the outer peripheral surface 131B of the lower end axial support portion 131A of the threaded spacer 131 serving as a support portion for the fixed cylinder, and the upper end surface 203B of the heat insulating material 203 abutting against the lower end surface 131C of the threaded spacer 131, and the lower end surface 203C abutting against the upper surface 129A of the base portion 129.

[0081] 9, the thickness portion of the heat insulating material 203 between the inner peripheral surface 203A and the outer peripheral surface 203D is formed in three layers, namely, from the inside out, inner peripheral layer 203E, intermediate layer 203F, and outer peripheral layer 203G. Inner peripheral layer 203E has a plurality of cavities 204C arranged in a ring shape and connected in the circumferential direction, intermediate layer 203F has a plurality of cavities 204D arranged in a ring shape and connected in the circumferential direction, and outer peripheral layer 203G has a plurality of cavities 204E arranged in a ring shape and connected in the circumferential direction.

[0082] As shown in Figure 9, the inner layer 203E of the heat insulating material 203 has approximately triangular cavities 204C arranged in a regular pattern along the circumferential direction, with their apexes and bases facing alternately inward (towards the inner surface 203A) and outward (towards the outer surface 203D), and the intermediate layer 203F has similarly approximately triangular cavities 204C arranged in a regular pattern, with their apexes and bases facing alternately inward (towards the inner surface 203A) and outward (towards the outer surface 203D), and with the bases of the approximately triangular cavities 204C in the inner layer 203E adjacent to the bases of the approximately triangular cavities 204D in the intermediate layer 203F. Meanwhile, the outer peripheral layer 203G is provided with cavities 204E, each of which has a substantially parallelogram shape when viewed from the opening direction, and which are regularly arranged along the circumferential direction with one side of the cavities adjacent to the base of the substantially triangular cavities 204D in the intermediate layer 203F. The cavities 204C, 204D, and 204E each penetrate the heat insulating material 203 from the upper end face 203B to the lower end face 203C. The cavities 204E in the outer peripheral layer 203G are formed in a parallelogram shape slightly inclined in the circumferential direction, but may also be formed in a substantially parallelogram shape not inclined in the circumferential direction, similar to the cavities 204B in FIG. 6. The height of the outer peripheral layer 203G from the lower end face 203C is slightly smaller than half the height of the inner peripheral layer 203E and the intermediate layer 203F.

[0083] In this way, by providing the approximately triangular cavity 204C and cavity 204D in the inner peripheral layer 203E and the intermediate layer 203F, respectively, and by providing the approximately parallelogram-shaped cavity 204E in the outer peripheral layer 203G, the rigidity of the heat insulating portion is increased and it is easier to form. Furthermore, by forming the cavity 204E in the outer peripheral layer 203G in an approximately parallelogram shape, the rigidity in the radial direction is selectively reduced, and even if the temperature-controlled parts inside (e.g., the threaded spacer 131, the base portion 129, etc.) thermally expand, the approximately parallelogram-shaped portion can deform and alleviate the load.

[0084] In the illustrated example, the cavities 204C and 204D formed in the inner peripheral layer 203E and the intermediate layer 203F of the thermal insulator 203, and the cavities 204E formed in the outer peripheral layer 203G, are formed as cavities 204C, 204D, and 204E that penetrate from the upper end face 203B to the lower end face 203C, respectively. However, in the thermal insulator 203 of the turbomolecular pump 100 of the second embodiment, if a blocking portion 203H that blocks one end side (the end face 203C side) of the cavities 204C, 204D, and 204E is provided in at least some of the cavities 204C, 204D, and 204E among the plurality of cavities 204C, 204D, and 204E as shown in (c) of Figure 9, the rigidity of the thermal insulator 203 can be further increased compared to a structure in which the cavities 204C, 204D, and 204E are through holes. The portions to be blocked may be intermediate portions or both end portions of the cavities 204C, 204D, and 204E.

[0085] Figure 10 shows a modified example of the third embodiment of the turbomolecular pump 100 shown in Figure 8. In this modified example, the thread groove pump mechanism section 202 is configured as a Sigbahn type pump mechanism, and the other configurations are the same as those of the second embodiment, so the same components are given the same reference numerals and redundant explanations will be omitted.

[0086] The thread groove pump mechanism 202 of the turbomolecular pump 100 shown in Figure 10 has a rotating disk 202A and a fixed disk 202B that face each other in the axial direction, and is structured so that a thread groove 202F as a spiral groove having a spiral ridge portion 202D and a spiral valley portion 202E is formed on both surfaces 202C of the fixed disk 202B that faces the rotating disk 202A.

[0087] Fixed disk 202B is fixed to outer cylinder 127 with both sides of its outer periphery sandwiched between fixed blade spacers 126A and 126B. On the other hand, rotating disk 202A is formed in a state where it protrudes in the shape of a rotating blade at a substantially right angle from the outer periphery of cylindrical portion 102d of rotating body 103, and is formed in a state where it faces both the upper and lower surfaces of fixed disk 202B.

[0088] The insulating material 203 is arranged so that the inner peripheral surface 203A of the insulating material 203 faces the outer peripheral surface 126D of the lower end axial support portion 126C of the fixed wing spacer 126B, which serves as a support portion for the fixed disc 202B, and the upper end surface 203B of the insulating material 203 abuts against the lower end surface 126E of the fixed wing spacer 126B, and further the lower end surface 203C abuts against the upper surface 129A of the base portion 129, and is sandwiched between the lower end surface 126E of the fixed wing spacer 126B and the upper surface 129A of the base portion 129.

[0089] 8 and 9 is provided between the fixed vane spacer 126B and the base portion 129 in the turbomolecular pump 100 of this modified example, so that, similarly to the second embodiment, it is possible to prevent the temperature on the turbomolecular pump mechanism 201 side and the thread groove pump mechanism portion 202 from affecting the temperature control on the base portion 129 side, and conversely, to prevent the controlled temperature on the base portion 129 side from affecting the turbomolecular pump mechanism 201 side and the thread groove pump mechanism portion 202. Furthermore, the thermal insulation material 203 is provided with approximately triangular cavities 204C and 204D in the inner circumferential layer 203E and the intermediate layer 203F, respectively, and with an approximately parallelogram-shaped cavity 204E in the outer circumferential layer 203G, thereby increasing the rigidity of the thermal insulation portion and making it easier to form. Furthermore, by forming cavity 204E of outer peripheral layer 203G in an approximately parallelogram shape, the radial rigidity is selectively reduced, and even if the inner parts thermally expand, the approximately parallelogram portion deforms, easing the load.

[0090] In the above embodiment, a structure has been disclosed in which the cavities 204C, 204D, and 204E of the insulating portion (insulating material 203) are formed along the axial direction, but they may also be formed along the radial direction.

[0091] Furthermore, the present invention can be modified in various ways without departing from the spirit of the present invention, and it is natural that the present invention also covers such modifications. [Explanation of symbols]

[0092] 100: Turbomolecular pump 101: Air intake 102: Rotor 102d: Cylindrical part (rotating cylinder) 103: Rotating body 104: Upper radial electromagnet 105: Lower radial electromagnet 106A: Axial electromagnet 106B: Axial electromagnet 107: Upper radial sensor 108: Lower radial sensor 109: Axial sensor 111: Metal disc 113: Rotor shaft 120: Protective bearing 121: Motor 122: Stator column 123:Fixed wing 123a :Fixed wing 123b :Fixed wing 123c: fixed wing 125: Fixed wing spacer 126A: Fixed wing spacer 126B: Fixed wing spacer 126C: Lower end axial support part 126D: Outer surface 126E: Bottom end surface 127: Outer cylinder 129: Base 129A:Top surface 131: Threaded spacer 131A: Lower end axial support part 131B: Outer surface 131C: Bottom end surface 131a: Thread groove 133: Exhaust port 141:Electronic circuit section 143: Substrate 145: Bottom lid 149:Water cooled pipe 150: Amplifier circuit 151: Electromagnet winding 161: Transistor 161a: Cathode terminal 161b: Anode terminal 162: Transistor 162a: Cathode terminal 162b: Anode terminal 165: Diode 165a: Cathode terminal 165b: Anode terminal 166: Diode 166a: Cathode terminal 166b: Anode terminal 171:Power supply 171a: Positive electrode 171b: Negative electrode 181: Current detection circuit 191: Amplifier control circuit 191a: Gate drive signal 191b: Gate drive signal 191c: Current detection signal 201: Turbomolecular pump mechanism 202: Thread groove pump mechanism 202A: Rotating disc 202B: Fixed disc 202C: Double-sided 202D: Spiral mountain 202E: Spiral valley 202F: Thread groove 203: Heat insulation material (heat insulation part) 203A: Inner peripheral surface 203B: End face 203C: End face 203D: Outer surface 203E: Inner layer 203F: Middle class 203G: Outer layer 203H:Occluded part 204A: Cavity 204B: Cavity 204C: Cavity 204D: Cavity 204E: Cavity 205: Beam I: Moment of inertia S: Cross-sectional area T: Plate thickness t: Beam thickness Tp1: Pulse width time Tp2: Pulse width time Ts: Control cycle iL: Electromagnet current iLmax: Current value iLmin: Current value

Claims

1. A vacuum pump having at least one of a heating function and a cooling function, The temperature-controlled part to be heated or cooled includes at least a thread groove pump mechanism, a heat insulating part having a hollow structure, the heat insulating part being disposed in the axial direction between the thread groove pump mechanism and the base, and having a plurality of cavities formed along the axial direction or the radial direction, and repeatedly provided in a circumferential direction; At least some of the cavities formed along the axial direction among the plurality of cavities are formed in the shape of a parallelogram inclined in the circumferential direction when viewed from the opening direction. A vacuum pump characterized by:

2. At least a part of the cavity is formed in a substantially triangular shape when viewed from the opening direction.

2. The vacuum pump according to claim 1.

3. The cavity is at least partially blocked.

3. A vacuum pump according to claim 1 or 2.

4. a turbomolecular pump mechanism including a rotor having a plurality of rotor blades arranged in multiple stages in the axial direction, and a plurality of stator blades disposed between the plurality of rotor blades, the temperature-controlled component is at least one of the plurality of stator blades, The heat insulating portion is disposed on a support portion of the fixed wing.

4. A vacuum pump according to claim 1.

5. The pump mechanism further includes a Holweck pump mechanism in which a screw groove is formed on at least one of the outer circumferential surface of the rotating cylinder and the inner circumferential surface of the fixed cylinder, which are opposed to each other in the radial direction, the temperature-controlled component is the fixed cylinder, The heat insulating portion is disposed on the support portion of the fixed cylinder.

5. A vacuum pump according to claim 1.

6. a Sigburn pump mechanism having a rotating disk and a fixed disk opposed to each other in the axial direction, wherein a spiral groove having spiral ridges and spiral valleys is formed on at least one surface of the fixed disk opposed to the rotating disk, the temperature-controlled component is the fixed disk, The heat insulating portion is disposed on the support portion of the fixed disk.

6. A vacuum pump according to claim 1.

7. A heat insulating member used in a vacuum pump having at least one of a heating function and a cooling function, The temperature-controlled part to be heated or cooled includes at least a thread groove pump mechanism, The pump mechanism has a hollow structure in which a plurality of cavities are arranged in the axial direction between the pump mechanism and the base, the cavities being formed along the axial direction or the radial direction and being repeatedly provided in the circumferential direction; At least some of the cavities formed along the axial direction among the plurality of cavities are formed in the shape of a parallelogram inclined in the circumferential direction when viewed from the opening direction. A heat insulating member characterized by:

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