WO2023095910A1 - Pompe à vide, élément d'espacement et procédé de fixation à boulon - Google Patents

Pompe à vide, élément d'espacement et procédé de fixation à boulon Download PDF

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Publication number
WO2023095910A1
WO2023095910A1 PCT/JP2022/043785 JP2022043785W WO2023095910A1 WO 2023095910 A1 WO2023095910 A1 WO 2023095910A1 JP 2022043785 W JP2022043785 W JP 2022043785W WO 2023095910 A1 WO2023095910 A1 WO 2023095910A1
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WIPO (PCT)
Prior art keywords
bolt
heated
spacer
vacuum pump
linear expansion
Prior art date
Application number
PCT/JP2022/043785
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English (en)
Japanese (ja)
Inventor
洋平 小川
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エドワーズ株式会社
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Filing date
Publication date
Application filed by エドワーズ株式会社 filed Critical エドワーズ株式会社
Publication of WO2023095910A1 publication Critical patent/WO2023095910A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/02—Selection of particular materials
    • F04D29/023—Selection of particular materials especially adapted for elastic fluid pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D19/00—Axial-flow pumps
    • F04D19/02—Multi-stage pumps
    • F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/60—Mounting; Assembling; Disassembling
    • F04D29/64—Mounting; Assembling; Disassembling of axial pumps
    • F04D29/644—Mounting; Assembling; Disassembling of axial pumps especially adapted for elastic fluid pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/58—Cooling; Heating; Diminishing heat transfer
    • F04D29/582—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps
    • F04D29/584—Cooling; Heating; Diminishing heat transfer specially adapted for elastic fluid pumps cooling or heating the machine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2260/00—Function
    • F05D2260/30—Retaining components in desired mutual position
    • F05D2260/31—Retaining bolts or nuts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2300/00—Materials; Properties thereof
    • F05D2300/50—Intrinsic material properties or characteristics
    • F05D2300/502—Thermal properties
    • F05D2300/5021—Expansivity
    • F05D2300/50212—Expansivity dissimilar

Definitions

  • the present invention relates to a vacuum pump, a spacer component, and a bolt fastening method. Specifically, in vacuum pumps, vacuum pumps, spacer parts, and fastening of bolts that can reduce the effects of thermal stress generated when the bolt and the material to be fastened thermally expand due to the heat generated during operation. Regarding the method.
  • Vacuum pumps are equipped with rotor blades and fixed blades fixed to a rotating shaft (shaft).
  • the rotating shaft is rotated at high speed, and high vacuum is required due to the interaction between the rotating blades and fixed blades rotating at high speed.
  • the air in the process chamber is evacuated.
  • the exhausted gas contains process gas used in the semiconductor manufacturing process, and various substances are inherent in this process gas. By accumulating these substances as products between internal parts in the vacuum pump, an event occurred in which parts that should not be in contact come into contact with each other. Since the rotating shaft (rotating blades) of a vacuum pump rotates at high speed, an accident due to contact may cause serious damage. Therefore, it is required to increase the temperature inside the vacuum pump in order to prevent accumulation of the product.
  • metals aluminum, stainless steel
  • iron and stainless steel are mainly used for bolts for fastening members.
  • These metals have different coefficients of linear expansion depending on their types, and even under the same temperature environment, the amounts of displacement of the materials are different.
  • the thermal stress generated by this difference in displacement generates an additional load in addition to the load generated when the vacuum pump is assembled (under normal temperature environment). There was a risk of damage to the bolted joints of the vacuum pump.
  • thermal stress means a force that suppresses deformation in a state where deformation is fixed.
  • FIG. 7A when there is no constraint (free deformation), no force acts at high temperature (during thermal expansion) and no thermal stress occurs.
  • FIG. 7B in a constrained state (a state in which deformation is not free), a reaction force is generated to prevent deformation. That is, thermal stress is the stress that occurs when deformation is hindered by temperature changes.
  • FIG. 8(a) an aluminum material A on the outer peripheral side and an iron material (for example, a bolt) B on the inner side are constrained at both ends. At this time, both lengths are the same at room temperature, and thermal stress is not generated. Then, as shown in FIG. 8(a), an aluminum material A on the outer peripheral side and an iron material (for example, a bolt) B on the inner side are constrained at both ends. At this time, both lengths are the same at room temperature, and thermal stress is not generated. Then, as shown in FIG.
  • bolt looseness will be described as damage originating from a bolt (fastened part).
  • FIG. 9B the presence or absence of “bolt looseness” is determined using a tightening diagram in design.
  • the tightening diagram is a graph showing the equilibrium relationship between the compressive force and the tensile force of the fastening/fastening parts, as shown in FIG. 9(a).
  • Patent Literature 1 discloses a technique for coping with the high temperature inside the vacuum pump while maintaining the pumping performance of the vacuum pump by arranging a heat-insulating component inside in order to cope with the high temperature inside the pump.
  • the present invention focuses on bolts, which are important in the assembly of mechanical products, and provides a vacuum pump, a spacer part, and a bolt fastening method that can prevent damage originating from the bolts in a high-temperature environment. With the goal.
  • the apparatus comprises a casing, a heated part that is arranged in the casing and heated by the generated heat, and a bolt for fixing the heated part in a predetermined position.
  • a vacuum pump when the heated part is fixed with the bolt and both parts are heated, thermal expansion in the fastening direction between the heated part and the bolt having a smaller coefficient of linear expansion than the heated part.
  • a vacuum pump characterized by having a thermal expansion amount difference reducing mechanism for reducing the amount difference.
  • the thermal expansion difference reducing mechanism includes a spacer part having a linear expansion coefficient smaller than that of the bolt at a portion where the head of the bolt and the heated part contact each other. , and the bolt is fastened through the spacer part.
  • the thermal expansion difference reduction mechanism is configured so that the difference between the thermal expansion amount of the spacer part and the heated part and the thermal expansion amount of the bolt falls within a certain range.
  • the vacuum pump according to claim 2 wherein the thickness of the spacer part in the fastening direction is determined.
  • the present invention according to claim 4 provides the vacuum pump according to claim 1, wherein the thermal expansion difference reduction mechanism reduces the thickness of the heated part in the fastening direction.
  • the heated part that is arranged in the casing of the vacuum pump and is heated by the generated heat is fixed at a predetermined position with a bolt, the head of the bolt and the heated part are fixed together. and a spacer part having a coefficient of linear expansion smaller than that of the bolt.
  • a spacer part having a coefficient of linear expansion smaller than the coefficient of linear expansion of the bolt is disposed at a location where the head of the bolt and the part to be heated come into contact with each other.
  • FIG. 1 is a diagram showing a schematic configuration example of a turbo-molecular pump according to an embodiment of the present invention
  • FIG. It is the figure which showed the circuit diagram of the amplifier circuit used by embodiment of this invention.
  • 4 is a time chart showing control when the detected value is greater than the current command value in the embodiment of the present invention
  • 4 is a time chart showing control when the detected value is smaller than the current command value in the embodiment of the present invention
  • FIG. 5 is a diagram for explaining bolted portions of a vacuum pump according to a second embodiment of the present invention.
  • FIG. 4 is a diagram for explaining thermal stress caused by temperature change; It is a figure for demonstrating the relationship between the difference of a linear expansion coefficient, and a thermal stress.
  • FIG. 4 is a diagram for explaining a tightening diagram for determining whether or not there is “loosening of a bolt”;
  • the parts to be heated (the parts to be fastened) that are heated by the heat generated (inside heat generated during operation, heating means, etc.) are connected by bolts.
  • a spacer is installed to adjust (eliminate) the difference between the linear expansion coefficients of the two in order to absorb the thermal stress caused by the difference between the coefficients of linear expansion of the two.
  • the spacer By installing this spacer, the amount of thermal expansion due to the linear expansion coefficient of the bolt (bolt material) and the linear expansion coefficient of the part to be heated and the spacer are aligned (approximated), thereby reducing the thermal stress of the bolt fastening part. It is possible to suppress the generation and reduce the thermal stress.
  • FIG. 1 Details of Embodiments Preferred embodiments of the present invention will now be described in detail with reference to FIGS. 1 to 6.
  • FIG. 1 Details of Embodiments Preferred embodiments of the present invention will now be described in detail with reference to FIGS. 1 to 6.
  • FIG. 1 A longitudinal sectional view of this turbomolecular pump (vacuum pump) 100 is shown in FIG.
  • a turbo-molecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127 .
  • a rotating body 103 Inside the outer cylinder 127, there is provided a rotating body 103 in which a plurality of rotating vanes 102 (102a, 102b, 102c), which are turbine blades for sucking and exhausting gas, are formed radially and in multiple stages on the periphery.
  • a rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is levitated in the air and position-controlled by, for example, a 5-axis control magnetic bearing.
  • the rotor 103 is generally made of metal such as aluminum or aluminum alloy.
  • 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 adjacent to the upper radial electromagnets 104 and corresponding to the upper radial electromagnets 104, respectively.
  • the upper radial sensor 107 is, for example, an inductance sensor or an eddy current sensor having a conductive winding, and detects the position of the rotor shaft 113 based on the change in the inductance of this conductive winding, which changes according to the position of the rotor shaft 113 .
  • This upper radial sensor 107 is configured to detect the radial displacement of the rotor shaft 113 , ie the rotor 103 fixed thereto, and send it to the controller 200 .
  • a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on the position signal detected by the upper radial sensor 107, as shown in FIG.
  • An amplifier circuit 150 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 .
  • the rotor shaft 113 is made of a high magnetic permeability material (iron, stainless steel, etc.) or the like, and is attracted by the magnetic force of the upper radial electromagnet 104 . Such adjustments are made independently in the X-axis direction and the Y-axis direction.
  • the lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107 so that the lower radial position of the rotor shaft 113 is set to the upper radial position. adjusted in the same way.
  • the axial electromagnets 106A and 106B are arranged so as to vertically sandwich a disk-shaped metal disk 111 provided below 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 axial displacement of the rotor shaft 113 and is configured to transmit its axial position signal to the controller 200 .
  • a compensation circuit having, for example, a PID adjustment function generates an excitation control command signal for each of the axial electromagnets 106A and 106B based on the axial position signal detected by the axial sensor 109.
  • the amplifier circuit 150 controls the excitation of the axial electromagnets 106A and 106B, respectively. is attracted upward, the axial electromagnet 106B attracts the metal disk 111 downward, and the axial position of the rotor shaft 113 is adjusted.
  • control device 200 appropriately adjusts the magnetic force exerted on the metal disk 111 by the axial electromagnets 106A and 106B, magnetically levitates the rotor shaft 113 in the axial direction, and holds the rotor shaft 113 in the space without contact. ing.
  • 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.
  • the motor 121 has a plurality of magnetic poles circumferentially arranged to surround the rotor shaft 113 .
  • Each magnetic pole is controlled by the control device 200 so as to rotationally drive the rotor shaft 113 via an electromagnetic force acting between the magnetic poles and the rotor shaft 113 .
  • the motor 121 incorporates a rotation speed sensor (not shown) such as a Hall element, resolver, encoder, etc., and the rotation speed of the rotor shaft 113 is detected by the detection signal of this rotation speed sensor.
  • phase sensor (not shown) is attached, for example, near the lower radial direction sensor 108 to detect the phase of rotation of the rotor shaft 113 .
  • the control device 200 detects the position of the magnetic pole using both the detection signals from the phase sensor and the rotational speed sensor.
  • a plurality of fixed wings 123 (123a, 123b, 123c%) are arranged with a slight gap from the rotary wings 102 (102a, 102b, 102c).
  • Each of the rotor 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 molecules of the exhaust gas downward by collision.
  • the fixed wings 123 (123a, 123b, 123c, . . . ) are made of metal such as aluminum, iron, stainless steel, or copper, or metal such as an alloy containing these metals as components.
  • the fixed blades 123 are also inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged inwardly of the outer cylinder 127 in a staggered manner with the stages of the rotary blades 102. ing.
  • the outer peripheral end of the fixed wing 123 is supported by being inserted between a plurality of stacked fixed wing spacers 125 (125a, 125b, 125c, . . . ).
  • the fixed wing spacer 125 is a ring-shaped member, and is made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components.
  • An outer cylinder 127 is fixed to the outer circumference of the stationary blade spacer 125 with a small gap therebetween.
  • a base portion 129 is provided at the bottom of the outer cylinder 127 .
  • An exhaust port 133 is formed in the base portion 129 and communicates with the outside. Exhaust gas that has entered the intake port 101 from the chamber (vacuum chamber) side and has been transferred to the base portion 129 is sent to the exhaust port 133 .
  • a threaded spacer 131 is arranged between the lower portion of the stationary blade spacer 125 and the base portion 129 depending on the application of the turbomolecular pump 100 .
  • the threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has a plurality of helical thread grooves 131a on its inner peripheral surface. It is stipulated.
  • the spiral direction of the thread groove 131 a is the direction in which the molecules of the exhaust gas move toward the exhaust port 133 when they move in the rotation direction of the rotor 103 .
  • a cylindrical portion 102d is suspended from the lowermost portion of the rotor 103 following the rotor blades 102 (102a, 102b, 102c).
  • the outer peripheral surface of the cylindrical portion 102d is cylindrical and protrudes toward the inner peripheral surface of the threaded spacer 131, and is adjacent to the inner peripheral surface of the threaded spacer 131 with a predetermined gap therebetween.
  • the exhaust gas transferred to the screw groove 131a by the rotary blade 102 and the fixed blade 123 is sent to the base portion 129 while being guided by the screw groove 131a.
  • the base portion 129 is a disk-shaped member that constitutes the base portion of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, or stainless steel.
  • the base portion 129 physically holds the turbo-molecular pump 100 and also functions as a heat conduction path, so a metal such as iron, aluminum, or copper that has rigidity and high thermal conductivity is used. is desirable.
  • the temperature of the rotor blades 102 rises due to frictional heat generated when the exhaust gas contacts the rotor blades 102, conduction of heat generated by the motor 121, and the like. It is transmitted to the stationary blade 123 side by conduction by molecules or the like.
  • the fixed blade spacers 125 are joined to each other at their outer peripheral portions, and transmit the heat received by the fixed blades 123 from the rotary blades 102 and the frictional heat generated when the exhaust gas contacts the fixed blades 123 to the outside.
  • the threaded spacer 131 is arranged on the outer circumference of the cylindrical portion 102d of the rotating body 103, and the inner peripheral surface of the threaded spacer 131 is provided with the thread groove 131a.
  • a thread groove is formed on the outer peripheral surface of the cylindrical portion 102d, and a spacer having a cylindrical inner peripheral surface is arranged around it.
  • the gas sucked from the intake port 101 may move the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the shaft
  • the electrical section is surrounded by a stator column 122 so as not to intrude into the electrical section composed of the directional electromagnets 106A and 106B, the axial direction sensor 109, etc., and the interior of the stator column 122 is maintained at a predetermined pressure with purge gas. It may drip.
  • a pipe (not shown) is arranged in the base portion 129, and the purge gas is introduced through this pipe.
  • the introduced purge gas is delivered 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 blade 102 .
  • the turbo-molecular pump 100 requires model identification and control based on individually adjusted unique parameters (for example, various characteristics corresponding to the model).
  • the turbomolecular pump 100 has an electronic circuit section 141 in its body.
  • the electronic circuit section 141 is composed of a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing the same, a board for mounting them, and the like.
  • the electronic circuit section 141 is accommodated, for example, below a rotational speed sensor (not shown) near the center of a base section 129 that constitutes the lower portion of the turbo-molecular pump 100 and is closed by an airtight bottom cover 145 .
  • some of the process gases introduced into the chamber have the property of becoming solid when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. be.
  • the pressure of the exhaust gas is lowest at the inlet 101 and highest at the outlet 133 .
  • the process gas is transported from the inlet 101 to the outlet 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 turbo molecules are formed. It adheres and deposits inside the pump 100 .
  • SiCl4 is a subscript, but to prevent misconversion of character codes, the subscripts are represented by normal letters below
  • a solid product eg, AlCl3
  • the above-described product is likely to solidify and adhere to portions near the exhaust port 133 and near the threaded spacer 131 where the pressure is high.
  • a heater (not shown) or an annular water cooling pipe 149 is wrapped around the outer circumference of the base portion 129 or the like, and a temperature sensor (for example, a thermistor) (not shown) is embedded in the base portion 129. Based on the signal from the temperature sensor, the heating of the heater and the cooling control by the water cooling pipe 149 are controlled (hereinafter referred to as TMS: Temperature Management System) so as to keep the temperature of the base portion 129 at a constant high temperature (set temperature). It is
  • the amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described.
  • a circuit diagram of this amplifier circuit 150 is shown in FIG.
  • an electromagnet winding 151 constituting the upper radial electromagnet 104 and the like has one end connected to a positive electrode 171a of a power source 171 via a transistor 161, and the other end connected to a current detection circuit 181 and a transistor 162. is connected to the negative electrode 171b of the power source 171 via the .
  • the transistors 161 and 162 are so-called power MOSFETs and have a structure in which a diode is connected between their source and drain.
  • the transistor 161 has its diode cathode terminal 161 a connected to the positive electrode 171 a and anode terminal 161 b 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.
  • the diode 165 for current regeneration has a cathode terminal 165a connected to one end of the electromagnet winding 151 and an anode terminal 165b connected to the negative electrode 171b.
  • the current regeneration diode 166 has its cathode terminal 166a connected to the positive electrode 171a and its anode terminal 166b connected to the other end of the electromagnet winding 151 via the current detection circuit 181. It has become so.
  • the current detection circuit 181 is composed of, for example, a Hall sensor type current sensor or an electric resistance element.
  • the amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled by five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each of the electromagnets, and ten amplifier circuits are provided for the power supply 171. 150 are connected in parallel.
  • the amplifier control circuit 191 is configured by, for example, a digital signal processor section (hereinafter referred to as a DSP section) not shown in the control device 200, and this amplifier control circuit 191 switches the transistors 161 and 162 on/off. It's like
  • 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) and a predetermined current command value. Then, based on this comparison result, the magnitude of the pulse width (pulse width times Tp1, Tp2) to be generated within the control cycle Ts, which is one cycle of PWM control, is determined. As a result, the gate drive signals 191 a and 191 b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of the transistors 161 and 162 .
  • a high voltage of about 50 V is used as the power source 171 so that the current flowing through the electromagnet winding 151 can be rapidly increased (or decreased).
  • a capacitor is usually connected between the positive electrode 171a and the negative electrode 171b of the power source 171 for stabilizing the power source 171 (not shown).
  • electromagnet current iL the current flowing through the electromagnet winding 151
  • electromagnet current iL the current flowing through the electromagnet winding 151
  • flywheel current is held.
  • the hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be suppressed.
  • high-frequency noise such as harmonics generated in the turbo-molecular pump 100 can be reduced.
  • the electromagnet current iL flowing through the electromagnet winding 151 can be detected.
  • the transistor when the detected current value (detected value) is greater than the current command value, the transistor is turned on only once during the control cycle Ts (for example, 100 ⁇ s) for a time corresponding to the pulse width time Tp1 as shown in FIG. Both 161 and 162 are turned on. Therefore, the electromagnet current iL during this period increases from the positive electrode 171a to the negative electrode 171b toward a current value iLmax (not shown) that can flow through the transistors 161,162.
  • both the transistors 161 and 162 are turned on for a time corresponding to the pulse width time Tp2 only once in the control cycle Ts, as shown in FIG. to off. Therefore, the electromagnet current iL during this period decreases from the negative electrode 171b to the positive electrode 171a toward a current value iLmin (not shown) that can be regenerated via the diodes 165,166.
  • either one of the transistors 161 and 162 is turned on after the pulse width times Tp1 and Tp2 have elapsed. Therefore, the flywheel current is held in the amplifier circuit 150 during this period.
  • FIG. 5A and 5B are diagrams for explaining bolted portions of the vacuum pump according to the first embodiment.
  • FIG. Specifically, it is a portion where the stator column 122 is fastened with the bolt 300 .
  • the stator column 122 which is the member to be fastened, is made of material A (eg, aluminum), while the bolt 300 is made of material B (eg, stainless steel).
  • the material to be fastened is fastened by a head 300a of a bolt 300 and a nut 302 (corresponding to the base portion 129 in the embodiment), as shown in FIG. 5(a).
  • a spacer 400 made of material C (eg, titanium, tungsten, copper, brass, nickel, kovar) having a smaller coefficient of linear expansion than material A and material B is arranged.
  • This spacer 400 corrects the difference in linear expansion coefficient (expansion amount) between material A and material B.
  • FIG. The spacer 400 has a columnar shape, but may have a prismatic shape. It is sized so as to be in complete contact with the head portion 300a of the bolt 300 .
  • a hole having a shape corresponding to the stator column 122, which is a material to be fastened, is provided and arranged therein. Adhesion or welding may be performed, but bolts 300 may be used for fastening and fixing. As the bolt 300, even if a headless embedded bolt (stud bolt) is fixed with a nut, the same fastening structure is obtained, and the effect of the present invention is exhibited.
  • the thickness of the spacer 400 (the axial length of the bolt 300) is determined so that the sum of the amount of expansion of the material A and the amount of expansion of the material C is equal to the amount of expansion of the material B. This means that the sum of the amount of expansion of bolt 300b and the amount of expansion of stator column 122 and spacer 400 in the axial direction should be equal. That is, if the difference in coefficient of linear expansion between material A and material B is small, the thickness of spacer 400 is small. becomes thicker. By adjusting the thickness of the spacer 400 in this way, it is possible to prevent thermal stress from occurring in the bolt 300 and the material to be fastened due to thermal expansion.
  • FIG. 6B a hole (counterbore) 500 is formed in the stator column 122, which is the material to be fastened, to reduce the difference in thermal elongation between the material to be fastened and the bolt 300.
  • the additional axial force on the tightening diagram becomes smaller (W1>W2), and loosening of the bolt can be reduced.
  • the depth of the hole (counterbore) 500 is desirably deeper from the viewpoint of thermal stress, but it is appropriately determined in consideration of the strength of the material to be fastened and the bolt 300 .
  • the stator column has been described as an example of the material to be fastened, but the present invention is not limited to this, and can be applied to other fastening points that undergo thermal expansion. can. For example, it can also be applied to the fastening point of the controller or the fastening point of the rotor shaft 113 . Also, the first embodiment and the second embodiment can be used together. That is, a hole (counterbore) 500 may be provided in the material to be fastened, and the stator 400 may be further installed.
  • turbomolecular pump vacuum pump
  • Intake port 102
  • Rotor blade 102d
  • Cylindrical portion 103
  • Rotor 113 Rotor shaft
  • Stator column 123
  • Fixed blade 125
  • Fixed blade spacer 127
  • Threaded spacer 131a Threaded groove
  • Exhaust port 200
  • Control device 300
  • Bolt 300a Bolt head Part 302
  • Nut 400 Stator 500 Hole

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Positive Displacement Air Blowers (AREA)
  • Containers, Films, And Cooling For Superconductive Devices (AREA)

Abstract

[Problème] Empêcher le desserrage d'un boulon dû à une contrainte thermique produite en raison des différences dans les coefficients de dilatation linéaire d'une pluralité d'éléments. [Solution] Lorsque des éléments à chauffer (éléments à fixer) chauffés par la chaleur interne sont fixés à l'aide d'un boulon dans une pompe à vide (100), un élément d'espacement (400) est installé afin de régler les coefficients de dilatation linéaire, en vue d'absorber une contrainte thermique produite en raison de la différence des coefficients de dilatation linéaire des deux éléments. L'installation dudit élément d'espacement (400) permet de supprimer la contrainte thermique d'une partie fixée du boulon (300) au moyen de l'égalisation du coefficient de dilatation linéaire du boulon (300) (le matériau du boulon) et du coefficient de dilatation linéaire de l'élément à chauffer plus l'élément d'espacement (400).
PCT/JP2022/043785 2021-11-29 2022-11-28 Pompe à vide, élément d'espacement et procédé de fixation à boulon WO2023095910A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2021193080A JP7527266B2 (ja) 2021-11-29 2021-11-29 真空ポンプ
JP2021-193080 2021-11-29

Publications (1)

Publication Number Publication Date
WO2023095910A1 true WO2023095910A1 (fr) 2023-06-01

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JP2002089519A (ja) * 2000-09-18 2002-03-27 Nec Machinery Corp 低熱膨張率材の締結方法
JP2005230856A (ja) * 2004-02-19 2005-09-02 Calsonic Kansei Corp 拡散接合用治具およびこれを用いた拡散接合方法
JP2017089582A (ja) * 2015-11-16 2017-05-25 エドワーズ株式会社 真空ポンプ

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002089519A (ja) * 2000-09-18 2002-03-27 Nec Machinery Corp 低熱膨張率材の締結方法
JP2005230856A (ja) * 2004-02-19 2005-09-02 Calsonic Kansei Corp 拡散接合用治具およびこれを用いた拡散接合方法
JP2017089582A (ja) * 2015-11-16 2017-05-25 エドワーズ株式会社 真空ポンプ

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