vacuum pump

Abstract

To provide a vacuum pump that can sufficiently prevent gas from flowing into a housing part for an electric part capable of rotating a rotating shaft.SOLUTION: A vacuum pump 100 comprises: an exterior body; a rotating shaft 113 contained in the exterior body, and rotatably supported; a housing part 122 housing an electric part capable of rotating the rotating shaft 113; a rotor 103 arranged outside the housing part 122, and constituted integrally with the rotating shaft 113; a partition wall part 141 constituting a portion of a stator arranged on the outer peripheral side of the rotor 103; and a rotating disk 107c extending in a radial direction from an outer peripheral surface of the rotor 103. The rotor 103 rotates, and thereby gas to be exhausted flows outside the rotor 103. At least a portion of opposed surfaces of the rotating disk 107c and the partition wall part 141 opposed to each other in an axial direction constitutes a non-contact seal structure for preventing gas from flowing into the housing part 122.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vacuum pump that evacuates a chamber to be evacuated. [Background technology]

[0002] In manufacturing equipment for semiconductors, liquid crystal displays, solar cells, LEDs (Light Emitting Diodes), etc. (hereinafter referred to as "semiconductors, etc."), a process gas is introduced into a vacuum chamber to form a thin film on a workpiece such as a wafer placed in the vacuum chamber, or to perform etching, etc. At this time, a vacuum pump is used to evacuate the vacuum chamber.

[0003] A turbomolecular pump, which is one type of vacuum pump, draws in process gas from an intake port and expels it from an exhaust port through the interaction between rotating blades attached to the outer surface of a rotor that rotates at high speed and fixed blades arranged alternately in the axial direction of the rotor's rotation shaft.

[0004] In this vacuum pump, some of the gas drawn in through the intake port may not be discharged through the exhaust port, but may flow into the housing that houses electrical components such as the magnetic bearings that support the rotor's rotating shaft and the motor that drives the rotating shaft, and may end up infiltrating the housing. If gas enters the housing, it may corrode the electrical components inside the housing, or reaction products may accumulate inside the housing, causing problems such as impeding the function of the vacuum pump.

[0005] As a countermeasure, for example, Patent Document 1 discloses a vacuum pump equipped with a shielding section that prevents contact between the gas and the containing section. The shielding section is made of a substantially annular member. The shielding section is disposed so that its upper end surface faces the bottom surface of the rotor cylindrical section, with a very small gap between them. This prevents contact between the gas and the containing section disposed inside the rotor cylindrical section. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-55673 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in a vacuum pump equipped with the above-mentioned shielding portion, the radial lengths of the opposing upper end surfaces of the shielding portion and the bottom surface of the rotor cylindrical portion are short, so there is a risk that the flow of gas into the storage portion may not be sufficiently prevented.

[0008] The present invention has been made in consideration of the above-mentioned situation, and aims to provide a vacuum pump that can sufficiently prevent gas from flowing into the housing for the electrical equipment that enables the rotation of the rotating shaft. [Means for solving the problem]

[0009] In order to achieve the above object, the vacuum pump of the present invention comprises: An exterior body; a rotating shaft that is rotatably supported within the exterior body; a housing portion that houses an electrical component that enables the rotation shaft to rotate; a rotor disposed outside the housing portion and integrally formed with the rotary shaft; a stator disposed on the outer periphery of the rotor; a rotating disk portion extending radially from an outer circumferential surface of the rotor, A vacuum pump in which exhaust gas flows outside the rotor due to rotation of the rotor, a first opposing surface having no irregularities and opposing the rotary disk portion and the stator in the axial direction; At least part of At least a portion of a second opposing surface, which is smooth and faces the outer peripheral surface of the rotor and the stator in the radial direction, forms a non-contact seal structure that prevents the gas from flowing into the accommodating portion.

[0010] In addition, the present invention Vacuum pump Pu is , An exterior body; a rotating shaft that is rotatably supported within the exterior body; a housing portion that houses an electrical component that enables the rotation shaft to rotate; a rotor disposed outside the housing portion and integrally formed with the rotary shaft; a stator disposed on the outer periphery of the rotor; a rotating disk portion extending radially from an outer circumferential surface of the rotor, A vacuum pump in which exhaust gas flows outside the rotor due to rotation of the rotor, at least a part of an axially opposing surface between the rotary disk portion and the stator forms a non-contact seal structure that prevents the gas from flowing into the accommodation portion, At least one of the opposing surfaces of the rotary disk portion and the stator is formed as an inclined surface. It is characterized by the fact that

[0011] In the above vacuum pump, The opposing surfaces of the rotary disk portion and the stator may be formed as inclined surfaces, and the inclination angles of the inclined surfaces may be the same.

[0012] In the above vacuum pump, the stator further includes a fixed disk portion that faces the rotary disk portion on the upstream side of the gas in the axial direction, The rotating disk portion and the fixed disk portion Third A first spiral groove for forming an exhaust mechanism is provided on at least one of the opposing surfaces. It is being This may be done.

[0013] In the above vacuum pump, The rotary disk portion may constitute the lowest stage of the exhaust mechanism.

[0014] In addition, the present invention vacuum pump teeth , An exterior body; a rotating shaft that is rotatably supported within the exterior body; a housing portion that houses an electrical component that enables the rotation shaft to rotate; a rotor disposed outside the housing portion and integrally formed with the rotary shaft; a stator disposed on the outer periphery of the rotor; a rotating disk portion extending radially from an outer circumferential surface of the rotor, A vacuum pump in which exhaust gas flows outside the rotor due to rotation of the rotor, at least a part of a first opposing surface without irregularities that faces the rotating disk portion and the stator in the axial direction and a second opposing surface without irregularities that faces the outer circumferential surface of the rotor and the stator in the radial direction constitutes a non-contact seal structure that prevents the gas from flowing into the accommodation portion, the stator further includes a fixed disk portion that faces the rotary disk portion on the upstream side of the gas in the axial direction, a first spiral groove for configuring an exhaust mechanism is provided on at least one of third opposing surfaces of the rotating disk portion and the fixed disk portion; the rotary disk portion constitutes the lowest stage of the exhaust mechanism, a flow straightening portion having a fourth opposing surface that faces the back surface of the rotary disk portion on the downstream side of the gas in the axial direction; It is characterized by the fact that

[0015] In the above vacuum pump, The flow straightening portion is disk-shaped and is connected to the rotary disk portion. The fourth The spiral groove portion may have a second spiral groove provided on the opposing surface.

[0016] In addition, the present invention Vacuum pump Pu is , An exterior body; a rotating shaft that is rotatably supported within the exterior body; a housing portion that houses an electrical component that enables the rotation shaft to rotate; a rotor disposed outside the housing portion and integrally formed with the rotary shaft; a stator disposed on the outer periphery of the rotor; a rotating disk portion extending radially from an outer circumferential surface of the rotor, A vacuum pump in which exhaust gas flows outside the rotor due to rotation of the rotor, at least a part of an axially opposing surface between the rotary disk portion and the stator forms a non-contact seal structure that prevents the gas from flowing into the accommodation portion, the stator further includes a fixed disk portion that faces the rotary disk portion on the upstream side of the gas in the axial direction, a first spiral groove for forming an exhaust mechanism is provided on at least one of the opposing surfaces of the rotating disk portion and the fixed disk portion; the non-contact seal structure is configured by a back surface of the rotary disk portion on the downstream side of the gas and an opposing surface that faces the stator in the axial direction, the rotary disk portion constitutes the lowest stage of the exhaust mechanism, a flow straightening portion having an opposing surface that faces a back surface of the rotary disk portion on the downstream side of the gas in the axial direction, the rectifying portion is a spiral groove portion having a disk shape and a second spiral groove provided on a surface facing the rotating disk portion, a cylindrical portion that is integral with the rotary disk portion and has an outer circumferential surface that faces the inner circumferential surface of the spiral groove portion, a thread groove provided on at least one of the inner circumferential surface of the spiral groove portion and the outer circumferential surface of the cylindrical portion; The non-contact seal structure is configured by a surface of the cylindrical portion on the downstream side of the gas and an opposing surface that faces the stator in the axial direction. It is characterized by:

[0017] In the above vacuum pump, the stator is heated by a heating means and includes a flow path defining portion that defines a flow path of the gas; The non-contact seal structure includes: The first opposing surface The rotary disk portion and the flow path defining portion may be configured by opposing surfaces that face each other in the axial direction. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a vacuum pump that can sufficiently prevent gas from flowing into the housing for the electrical component that enables the rotation of the rotary shaft. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1(A) is a vertical cross-sectional view showing the configuration of a vacuum pump according to a first embodiment of the present invention, and FIG. 1(B) is an enlarged view of part C in FIG. 1(A). [Figure 2] 2 is an explanatory diagram showing a schematic configuration of a fixed disk of a vacuum pump taken along line DD in FIG. 1(A). FIG. [Figure 3] 1 is a circuit diagram of an amplifier circuit included in a vacuum pump according to a first embodiment of the present invention. [Figure 4] 5 is a time chart showing control when a current command value in the vacuum pump according to the first embodiment of the present invention is larger than a detection value. [Figure 5] 5 is a time chart showing control when a current command value in the vacuum pump according to the first embodiment of the present invention is smaller than a detection value. [Figure 6] 6A is a longitudinal sectional view showing the configuration of a vacuum pump according to a second embodiment of the present invention, and FIG. 6B is an enlarged view of part E in FIG. 6A. [Figure 7] FIG. 10 is a partially enlarged longitudinal sectional view showing the configuration of a vacuum pump according to a third embodiment of the present invention. [Figure 8] FIG. 10 is a partially enlarged longitudinal sectional view showing the configuration of a vacuum pump according to a fourth embodiment of the present invention. [Figure 9] FIG. 10 is a partially enlarged longitudinal sectional view showing the configuration of a vacuum pump according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum pump according to an embodiment of the present invention will now be described with reference to the drawings.

[0021] (First embodiment) A vacuum pump according to a first embodiment will be described with reference to Fig. 1. As shown in Fig. 1(A), the vacuum pump 100 is a composite vacuum pump equipped with a turbomolecular pump section 100a on the upstream side of the inflowing gas and a Siegbahn type pump section 100b on the downstream side.

[0022] This vacuum pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127. A rotor 103 is provided inside the outer cylinder 127. A plurality of rotor blades 102 (102a, 102b, 102c, etc.), which are turbine blades for sucking and exhausting gas, and a plurality of rotor disks 107 (107a, 107b, 107c) are formed radially and in multiple stages around the periphery of this rotor 103, and extend radially. The rotor blades 102 constitute a part of the turbomolecular pump section 100a, and the rotor disk 107 constitutes a part of the Siegbahn-type pump section 100b. The rotor blades 102 are arranged upstream of the rotor 103, and the rotor disk 107 is arranged downstream of the lowest rotor blade 102.

[0023] A rotating shaft 113 is attached to the center of the rotor 103, and the rotating shaft 113 and the rotor 103 are integrally configured. The rotating shaft 113 is supported so as to be freely rotatable, and is supported in the air by, for example, a five-axis controlled magnetic bearing, and its position is controlled. The rotor 103 is generally made of a metal such as aluminum or an aluminum alloy.

[0024] The upper radial electromagnets 104 are arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 114 are provided adjacent to the upper radial electromagnets 104 and corresponding to each upper radial electromagnet 104. The upper radial sensors 114 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotating shaft 113 based on changes in the inductance of the conductive windings, which change depending on the position of the rotating shaft 113. The upper radial sensors 114 are configured to detect the radial displacement of the rotating shaft 113, i.e., the rotor 103 fixed thereto, and send the detected displacement to the control device 300.

[0025] In this control device 300, 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 114, and an amplifier circuit 150 (described later) shown in Figure 3 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotating shaft 113.

[0026] The rotating shaft 113 is made of a material with high magnetic permeability (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. Furthermore, the lower radial electromagnet 105 and the lower radial sensor 115 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 114, and adjust the radial position of the lower side of the rotating shaft 113 in the same manner as the radial position of the upper side.

[0027] Furthermore, axial electromagnets 106a and 106b are arranged above and below a circular metal disk 111 provided below the rotating shaft 113. The metal disk 111 is made of a highly magnetic permeable material such as iron. An axial sensor 108 is provided to detect the axial displacement of the rotating shaft 113, and an axial position signal is sent to the control device 300.

[0028] In the control device 300, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for the axial electromagnet 106a and the axial electromagnet 106b based on the axial position signal detected by the axial sensor 108, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106a and the axial electromagnet 106b based on these excitation control command signals, so that the axial electromagnet 106a attracts the metal disc 111 upward by magnetic force, and the axial electromagnet 106b attracts the metal disc 111 downward, thereby adjusting the axial position of the rotating shaft 113.

[0029] In this way, the control device 300 appropriately adjusts the magnetic force that the axial electromagnets 106a and 106b exert on the metal disk 111, magnetically levitating the rotating 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.

[0030] On the other hand, motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround rotating shaft 113. Each magnetic pole is controlled by control device 300 so as to rotate rotating shaft 113 via electromagnetic force acting between the magnetic pole and rotating shaft 113. Also, motor 121 incorporates a rotation speed sensor (not shown), such as a Hall element, resolver, or encoder, and the rotation speed of rotating shaft 113 is detected by the detection signal of this rotation speed sensor.

[0031] Furthermore, a phase sensor (not shown) is attached, for example, near the lower radial sensor 115, to detect the phase of rotation of the rotating shaft 113. The control device 300 uses the detection signals of both this phase sensor and the rotational speed sensor to detect the position of the magnetic pole.

[0032] A plurality of stator blades 123 (123a, 123b, 123c...) are arranged at small gaps from the rotor blades 102 (102a, 102b, 102c...). The turbomolecular pump section 100a is composed of the rotor blades 102 and the stator blades 123. The rotor blades 102 (102a, 102b, 102c...) are formed at an angle of a predetermined degree from a plane perpendicular to the axis of the rotation shaft 113 in order to transport exhaust gas molecules downward by collision with them. The stator blades 123 (123a, 123b, 123c...) are made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing any of these metals as an ingredient.

[0033] Similarly, the fixed blades 123 are formed at an angle at a predetermined angle from a plane perpendicular to the axis of the rotary shaft 113, and are arranged alternately with the stages of the rotary blades 102 toward the inside of the outer cylinder 127. The outer peripheral ends of the fixed blades 123 are supported in a state where they are inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0034] On the other hand, a plurality of fixed disks 126 (126a, 126b) are arranged with gaps between them and the rotating disks 107 (107a, 107b, 107c). The Siegbahn type pump section 100b is composed of the rotating disk 107 and the fixed disks 126. The fixed vanes 123 and the fixed disks 126 form part of the stator.

[0035] The rotating disks 107 (107a, 107b, 107c) are formed perpendicular to the axis of the rotating shaft 113, and have a radial cross section tapered toward the periphery. The lower surface 109c of the lowest rotating disk 107c will be described later. A plurality of peaks 131 (131a, 131b) and a plurality of valleys 132 (132a, 132b) are formed on both the upstream and downstream sides of the gas of the fixed disk 126 (126a, 126b), and the plurality of peaks 131 (131a, 131b) and the plurality of valleys 132 (132a, 132b) form a plurality of spiral grooves (corresponding to first spiral grooves) as shown in FIG. 2. The opposing surfaces of the rotating disk 107 and the fixed disk 126 (corresponding to the third opposing surface) At least one of the above may be provided with a spiral groove for forming an exhaust mechanism.

[0036] The fixed disks 126 (126a, 126b) are formed perpendicular to the axis of the rotary shaft 113 and are arranged alternately with the stages of the rotary disk 107 toward the inside of the exterior part 129a. The outer peripheral ends of the fixed disks 126 (126a, 126b) are supported by being inserted between a plurality of stacked fixed disk spacers 128 (128a, 128b, 128c). The axial height of the fixed disk spacers 128 (128a, 128b, 128c) is set to decrease toward the downstream side of the gas. This causes the volume of the flow path to gradually decrease toward the downstream side of the gas, compressing the gas.

[0037] The Siegbahn type molecular pump section 100b can exhaust gas molecules that have diffused into the flow path of the spiral grooves provided in the fixed disk 126 by imparting tangential momentum to the gas molecules using the rotating disk 107, and the spiral grooves provide a favorable directionality toward the exhaust direction.

[0038] The fixed vane spacer 125 and the fixed disk spacer 128 are ring-shaped components made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed vane spacer 125 with a small gap therebetween, and an exterior component 129a is fixed to the outer periphery of the fixed disk spacer 128 with a small gap therebetween. The outer cylinder 127, exterior component 129a, and exterior component 129b are arranged in this order from the upstream gas side to form the exterior body of the vacuum pump 100. The rotating shaft 113 is enclosed in this exterior body. A base portion 133 is arranged at the bottom of the exterior body. An exhaust port 134 is formed in the exterior component 129b and communicates with the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) to be evacuated and is transported to the base portion 133 is sent to the exhaust port 134.

[0039] The base 133 is a disk-shaped member that forms the base of the vacuum pump 100, and is generally made of metal such as iron, aluminum, or stainless steel. The base 133 not only physically holds the vacuum 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. The base 133 is also provided with a water-cooled pipe 133a for cooling electrical components such as the motor 121.

[0040] Furthermore, in order to prevent gas sucked in from the intake port 101 from entering the electrical equipment section, which is made up of the upper radial electromagnet 104, the upper radial sensor 114, the motor 121, the lower radial electromagnet 105, the lower radial sensor 115, the axial electromagnets 106a and 106b, the axial sensor 108, etc. and enables the rotation of the rotating shaft 113, the electrical equipment section is surrounded by a housing section 122. In other words, the electrical equipment section is housed in the housing section 122. The interior of this housing section 122 may be kept at a predetermined pressure by a purge gas.

[0041] In this case, piping (not shown) is provided in the base portion 133, and purge gas is introduced through this piping. The introduced purge gas is sent to the exhaust port 134 through gaps between the protective bearing 120 and the rotating shaft 113, between the rotor and stator of the motor 121, and between the housing portion 122 and the inner cylindrical portion of the rotor blades 102.

[0042] Here, the vacuum pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that are individually adjusted and specific to the model. To store these control parameters, the vacuum pump 100 is provided with an electronic circuit unit 144 within its body. The electronic circuit unit 144 is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 146 for mounting these components. The electronic circuit unit 144 is housed below a rotational speed sensor (not shown) near the center of the base unit 133 that constitutes the lower part of the vacuum molecular pump 100, and is closed by an airtight bottom lid 147.

[0043] Next, with regard to the vacuum pump 100 configured as above, the amplifier circuit 150 that controls excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106a and 106b will be described with reference to FIG.

[0044] One end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to the positive electrode 171a of the power supply 171 via a transistor 161, and the other end is connected to the 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) not shown in the figure of the control device 300, and this amplifier control circuit 191 is configured to switch the transistors 161 and 162 on / off.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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 vacuum 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.

[0053] 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 during a control cycle Ts (for example, 100 μs), as shown in Fig. 4. 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.

[0054] 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 the control cycle Ts, as shown in Fig. 5. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from the negative pole 171b to the positive pole 171a via diodes 165 and 166.

[0055] 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.

[0056] Here, we will explain how exhaust gas is sucked in and discharged in the vacuum pump 100. In the upstream turbomolecular pump section 100a, when the rotor 102 is rotated together with the rotary shaft 113 by the motor 121, the rotor 102 and the fixed blades 123 act to suck exhaust gas from the chamber to be evacuated through the intake port 101. The rotation speed of the rotor 102 is typically 20,000 rpm to 90,000 rpm, and the peripheral velocity at the tip of the rotor 102 reaches 200 m / s to 400 m / s. The exhaust gas sucked in through the intake port 101 passes between the rotor 102 and the fixed blades 123 on the outside of the rotor 103, and is transferred to the downstream Siegbahn-type pump section 100b. In the Siegbahn type molecular pump section 100b, the interaction between the rotating disk 107, which is driven to rotate in the same manner as the rotor blades 102, and the fixed disk 126, which is provided with spiral grooves, gives the transferred gas molecules a preferential direction toward the exhaust port 134. Then, the exhaust gas passes between the rotating disk 107 and the fixed disk 126, which are on the outside of the rotor 103, and is discharged from the exhaust port 134.

[0057] At this time, the temperatures of the rotor 102 and the rotor disk 107 rise due to frictional heat generated when the exhaust gas comes into contact with them and the conduction of heat generated by the motor 121, but this heat is transferred to the stator 123 or the stator disk 126 by radiation or conduction through gas molecules in the exhaust gas.

[0058] The fixed vane spacers 125 are joined together at their outer peripheries, and transmit to the outside heat received by the fixed vanes 123 from the rotating vanes 102 and frictional heat generated when exhaust gas comes into contact with the fixed vanes 123. Similarly, the fixed disk spacers 128 are joined together at their outer peripheries, and transmit to the outside heat received by the fixed disks 126 from the rotating disks 107 and frictional heat generated when exhaust gas comes into contact with the fixed disks 126.

[0059] Next, a description will be given of characteristic features of the vacuum pump 100 according to this embodiment. If the exhaust gas transferred by the downstream Siegbahn-type molecular pump section 100b flows into the housing section 122, which houses the electrical components that enable the rotation shaft 113 to rotate, without being sent to the exhaust port 134, and enters the housing section 122, the electrical components in the housing section 122 may corrode or reaction products may accumulate in the housing section 122, impairing the performance of the vacuum pump 100. For this reason, the vacuum pump 100 according to this embodiment has a non-contact seal structure that prevents gas from flowing into the housing section 122.

[0060] This non-contact seal structure will now be described. The partition wall portion 141 defines a flow path 142 for exhaust gas. As shown in FIG. 1(B), the partition wall portion 141 is composed of a base portion 141a, a cylindrical portion 141b erected from the base portion 141a, and an inward flange portion 141c extending radially inward from the upper end of the cylindrical portion 141b. The partition wall portion 141 is disposed on the outer circumferential side of the accommodation portion 122 and the rotor 103. The partition wall portion 141 constitutes a part of the stator. In FIG. 1, only the partition wall portion 141 and the rotor 103 are hatched to facilitate understanding.

[0061] A lower surface 109c (a back surface not facing the lowermost fixed disk 126b) of the lowermost rotating disk (rotating disk portion) 107c on the downstream side of the gas and an upper surface 141d of the inward flange portion 141c face each other in the axial direction. (corresponding to the first opposing surface) The opposing surfaces form a non-contact seal structure that prevents gas from flowing into the storage portion 122. Although these opposing surfaces are provided around the entire circumference, it is sufficient that the opposing surfaces are provided so that at least a portion forms a non-contact seal structure. A gap G1 between the lower surface 109c of the rotating disk 107c and the upper surface 141d of the inward flange portion 141c is set to a minute gap. The gap G1 between the lower surface 109c of the rotating disk 107c and the upper surface 141d of the inward flange portion 141c is appropriately set to, for example, about 1 mm to 1.5 mm.

[0062] In this non-contact seal structure, the drag effect caused by the rotation of the rotating disk 107c causes gas to be discharged radially outward from a gap G1 between the lower surface 109c of the rotating disk 107c and the upper surface 141d of the inward flange portion 141c toward the gas flow path 142 and the exhaust port 134. The longer the length of the surface where the lower surface 109c of the rotating disk 107c and the upper surface 141d of the inward flange portion 141c face each other in the axial direction (corresponding to the length of the upper surface 141d), the better the exhaust performance and sealing performance due to the drag effect. The lower surface 109c of the rotating disk 107c and the upper surface 141d of the inward flange portion 141c are formed as inclined surfaces that rise from the inside to the outside, with the inclination direction and angle being the same. As a result, the length of the surface where the lower surface 109c of the rotating disk 107c and the upper surface 141d of the inward flange portion 141c face each other in the axial direction is longer than when the lower surface 109c of the rotating disk 107c and the upper surface 141d of the inward flange portion 141c are both horizontal surfaces, thereby improving exhaust performance.

[0063] Furthermore, since the exhaust performance due to the drag effect of the rotating disk 107c improves as the peripheral speed of the rotating disk 107c increases, it is preferable to provide a non-contact seal structure as close to the outer periphery of the rotating disk 107c as possible. By providing a non-contact seal structure on the outer periphery of the rotating disk 107c, there is more room to widen the gap G1, making it easier to process and assemble the rotating disk 107c and the partition wall 141. However, it is necessary to consider the balance with the gas flow path area. The size of the radial gap between the inward flange portion 141c of the partition wall 141 and the rotor 103 may be approximately the same as the gap G1. The radially opposing surface between the inward flange portion 141c of the partition wall portion 141 and the rotor 103 corresponds to a second opposing surface.

[0064] The partition wall 141 has a heater 143 provided on its base 141a as a heating means. Therefore, the partition wall 141 also functions as a heater spacer. The partition wall 141 is fixed to the base 133, the exterior component 129b, etc., via a heat insulating member. 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 vacuum pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 134. If the pressure of the process gas exceeds a predetermined value or its temperature falls below a predetermined value while the process gas is being transferred from the intake port 101 to the exhaust port 134, the process gas solidifies and adheres to and accumulates inside the vacuum pump 100.

[0065] For example, when SiCl4 is used as the process gas in an Al etching system, the low vacuum (760 [torr] to 10 -2 The vapor pressure curve shows that at low pressures (approximately 20°C) and pressures of 10 ...

[0066] Therefore, in order to solve this problem, a heater 143 and a circular water-cooled pipe (not shown) are wrapped around the partition wall portion 141 that defines the gas flow path 142, and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the partition wall portion 141, and heating by the heater 143 and cooling by the water-cooled pipe are controlled based on the signal from this temperature sensor so as to maintain the temperature of the partition wall portion 141 at a constant high temperature (set temperature) (hereinafter referred to as TMS; Temperature Management System).

[0067] In this manner, in this embodiment, the lower surface 109c of the lowest rotating disk 107c and the opposing surface that faces the upper surface 141d of the inward flange portion 141c in the axial direction form a contactless seal structure that prevents gas from flowing into the accommodation portion 122, so that a contactless seal structure with a relatively long opposing surface can be realized. Therefore, a vacuum pump that can sufficiently prevent exhaust gas from flowing into the accommodation portion 122 can be provided.

[0068] (Second embodiment) A vacuum pump according to a second embodiment will be described with reference to FIG. 6. In the second embodiment, components similar to those of the vacuum pump according to the first embodiment are denoted by the same reference numerals, and their description will be omitted. Only differences from the first embodiment will be described. As shown in FIG. 6(A), a vacuum pump 200 according to the second embodiment is a vacuum pump consisting of only a turbomolecular pump section 100a. A plurality of rotating blades 102 (102a, 102b, 102c, etc.) are formed radially and in multiple stages on the periphery of a rotor 203, and a rotating disk section 201 extends radially downstream of the lowest rotating blade 102. The rotating disk section 201 is formed perpendicular to the axis of the rotating shaft 113, with an upper surface formed as an inclined surface and a lower surface 201a formed as a horizontal surface. Unlike the rotating blades 102, the rotating disk section 201 is not directly involved in the discharge of exhaust gas. In FIG. 6, for ease of understanding, only the housing portion 122 and the rotor 203 are hatched.

[0069] The upright portion 241 is erected along the outer periphery of the housing portion 122 and the rotor 203. The upright portion 241 is low and cylindrical. The upright portion 241 constitutes part of the stator. The lower surface 201a on the downstream side of the rotating disk portion 201 and the upper surface 241a of the upright portion 241 face each other in the axial direction, as shown in FIG. 6(B). This facing surface forms a non-contact seal structure that prevents gas from flowing into the housing portion 122. While this facing surface extends over the entire circumference, it is sufficient that the facing surface is provided so that at least a portion of the facing surface forms a non-contact seal structure. A gap G2 between the lower surface 201a of the rotating disk portion 201 and the upper surface 241a of the upright portion 241 is a minute gap, and the size of the gap G2 is similar to that of the gap G1. The lower surface 201a of the rotating disk portion 201 and the upper surface 241a of the upright portion 241 are horizontal surfaces, not inclined surfaces.

[0070] In this embodiment, a non-contact seal structure that prevents gas from flowing into the accommodating section 122 can be formed by extending the rotating disk section 201, which is not directly involved in the discharge of exhaust gas, from the periphery of the rotor 203.

[0071] (Third embodiment) A vacuum pump according to a third embodiment will be described with reference to FIG. 7. In the third embodiment, the same components as those in the vacuum pump according to the first embodiment will be assigned the same reference numerals, and their description will basically be omitted. Only the differences from the first embodiment will be described. A vacuum pump 400 according to the third embodiment can solve the problem of reduced exhaust performance when, for example, there is a sudden expansion of the flow path on the downstream side of the gas of the lowest rotating disk 107c. As shown in FIG. 7, the vacuum pump 400 has a spiral groove portion (Siegbahn portion) 410 formed in a disk shape on the rear side, which is the downstream side of the gas of the lowest rotating disk 107c. The spiral groove portion 410 is formed on the upstream side of the gas and faces the surface facing the lowest rotating disk 107c. (corresponding to the fourth opposing surface)Similar to the fixed disk 126, a plurality of peaks 411 and a plurality of valleys 412 are formed on the fixed disk 128, and a plurality of spiral grooves (corresponding to second spiral grooves) are formed by the plurality of peaks 411 and the plurality of valleys 412. The spiral groove 410 is supported with its outer peripheral end inserted between the lowest fixed disk spacer 128c and the base 141a of the partition wall 141.

[0072] In the third embodiment, a spiral groove 410 is provided on the back side of the lowest rotating disk 107c, and the interaction between the lowest rotating disk 107c and the spiral groove 410 provides a preferential direction to the transferred gas molecules toward the exhaust port 134. In other words, the spiral groove 410 serves as a flow rectifier that rectifies the exhaust gas and, in combination with the exhaust action, improves the exhaust performance of the exhaust gas. This improves the exhaust performance of the vacuum pump 400, and the non-contact seal structure effectively prevents the exhaust gas from flowing into the accommodation section 122.

[0073] (Fourth embodiment) A vacuum pump according to a fourth embodiment will be described with reference to FIG. 8. In the fourth embodiment, components similar to those of the vacuum pump according to the third embodiment are denoted by the same reference numerals, and their description will basically be omitted. Only differences from the third embodiment will be described. As shown in FIG. 8, a vacuum pump 500 according to the fourth embodiment has a cylindrical portion 510. The cylindrical portion 510 is fitted to the rotor 103 and fixed integrally to the lower part of the lowest rotating disk 107c, so that the lowest rotating disk 107c and the cylindrical portion 510 are integrally formed. The cylindrical portion 510 rotates together with the rotating disk 107c and the rotor 103. A screw groove (spiral groove) 510a is formed on the outer peripheral surface of the cylindrical portion 510, and the outer peripheral surface of the cylindrical portion 510 on which the screw groove 510a is formed faces the inner and outer peripheral surfaces of the spiral groove portion 410. The cylindrical portion 510 having a screw groove 510a formed on the outer circumferential surface and the spiral groove portion 410 constitute a screw groove pump portion.

[0074] A lower surface 510b, which is the downstream gas surface of the cylindrical portion 510, and an upper surface 141d of the inward flange portion 141c face each other in the axial direction. These facing surfaces form a non-contact seal structure that prevents gas from flowing into the storage portion 122. Although these facing surfaces are provided around the entire circumference, it is sufficient that the facing surfaces are provided so that at least a portion forms a non-contact seal structure. A gap G3 between the lower surface 510b of the cylindrical portion 510 and the upper surface 141d of the inward flange portion 141c is defined as a minute gap. The lower surface 510b of the cylindrical portion 510 and the upper surface 141d of the inward flange portion 141c are formed horizontally, not inclined.

[0075] In the fourth embodiment, the cylindrical portion 510, on which the thread groove 510a is formed, rotates together with the rotor 103, so that the exhaust gas is guided along the thread groove 510a and transported toward the exhaust port 134. This improves the exhaust performance of the exhaust gas, in combination with the exhaust gas straightening effect and exhaust action of the spiral groove portion 410 that faces the thread groove 510a on the outer circumferential surface. This further improves the exhaust performance of the vacuum pump 500, and also provides a non-contact seal structure formed by the lower surface 510b of the cylindrical portion 510 and the upper surface 141d of the inward flange portion 141c, thereby sufficiently preventing the exhaust gas from flowing into the accommodation portion 122.

[0076] (Fifth embodiment) A vacuum pump according to a fifth embodiment will be described with reference to Fig. 9. In the fifth embodiment, components similar to those of the vacuum pump according to the fourth embodiment will be assigned the same reference numerals, and descriptions thereof will basically be omitted. Only differences from the fourth embodiment will be described. In a vacuum pump 600 according to the fifth embodiment, as shown in Fig. 9, a thread groove (spiral groove) 410a is formed not on the outer peripheral surface of a cylindrical portion 510 but on the inner peripheral surface of a spiral groove portion 410 that faces the outer peripheral surface of the cylindrical portion 510. A thread groove pump portion is formed by the cylindrical portion 510 and the spiral groove portion 410 having the thread groove 410a formed on its inner peripheral surface.

[0077] In the fifth embodiment, the rotation of the cylindrical portion 510 together with the rotor 103 causes the exhaust gas to be guided along the thread grooves 510a formed on the inner circumferential surface of the spiral groove portion 410 and transferred toward the exhaust port 134, thereby improving the exhaust performance of the exhaust gas in combination with the exhaust gas straightening effect and exhaust action of the spiral groove portion 410. This further improves the exhaust performance of the vacuum pump 600, and also provides a non-contact seal structure formed by the lower surface 510b of the cylindrical portion 510 and the upper surface 141d of the inward flange portion 141c, thereby sufficiently preventing the exhaust gas from flowing into the accommodation portion 122.

[0078] Although the present invention has been described above with reference to exemplary embodiments, the present invention is not limited to the above-described exemplary embodiments, and various modifications and combinations are possible in addition to the modifications described above. For example, the first exemplary embodiment described an example of a combined vacuum pump equipped with a turbomolecular pump section 100a and a Siegbahn-type pump section 100b, and the second exemplary embodiment described an example of a vacuum pump consisting only of a turbomolecular pump section 100a. However, for a vacuum pump consisting only of a Siegbahn-type pump section 100b, it is also possible to configure a non-contact seal structure by using the lowest rotating disk, or to configure a non-contact seal structure by providing a new rotating disk section that is not directly involved in discharging exhaust gas.

[0079] Furthermore, in the above first, third to fifth embodiments, examples have been described in which the rotating disk 107 (107a, 107b, 107c) has a radial cross section tapered toward the periphery, but it does not necessarily have to be tapered, and for example, both the upstream and downstream sides may be formed as horizontal surfaces.

[0080] Furthermore, in the first, third to fifth embodiments, examples have been described in which the partition wall portion 141 is integrated with the heater spacer, but the partition wall portion 141 may be a separate part from the heater spacer.

[0081] Furthermore, in the above-described first and third embodiments, examples have been described in which the lower surface 109c of the rotating disk 107c and the upper surface 141d of the inward flange portion 141c are both formed as inclined surfaces, but the present invention can also be applied even if only one of the surfaces is formed as an inclined surface.

[0082] In addition, in the above second embodiment, the lower surface 201a of the rotating disk portion 201 and the upper surface 241a of the standing portion 241 are horizontal surfaces, and in the above fourth and fifth embodiments, the lower surface 510b of the cylindrical portion 510 and the upper surface 141d of the inward flange portion 141c are horizontal surfaces. However, these surfaces may be formed as inclined surfaces having the same inclination direction and approximately the same inclination angle.

[0083] In addition, in the above fourth embodiment, an example was described in which a screw groove 510a is provided on the outer peripheral surface of the cylindrical portion 510, and in the above fifth embodiment, an example was described in which a screw groove 410a is provided on the inner peripheral surface of the spiral groove portion 410, but a screw groove pump portion may be configured by providing both the screw groove 510a and the screw groove 410a.

[0084] Furthermore, in the second embodiment, the spiral groove portion 410 in the third embodiment may be provided on the rear side, which is the downstream side of the gas, of the rotating disk portion 201. Furthermore, in the second embodiment, the cylindrical portion 510 in the fourth embodiment may be fitted to the rotor 203 and fixed integrally to the lower part of the rotating disk portion 201.

[0085] In the fourth and fifth embodiments, the cylindrical portion 510 may be formed integrally with the lowermost rotary disk 107c and the rotor 103. [Explanation of symbols]

[0086] 100,200,400,500,600 Vacuum Pump 100a turbo molecular pump section 100b Siegbahn type pump section 103,203 rotor 107c Rotating disc 109c Lower side 113 Rotation axis 122 Storage unit 126 Fixed disc 141 Bulkhead section 141c Inward flange 141d top surface 142 Channel 143 Heater 201 Rotating disc section 201a Lower side 241 Standing section 241a Top side 410 Spiral groove 410a screw groove (spiral groove) 510 Cylindrical part 510a screw groove (spiral groove) 510b Bottom side

Claims

1. An exterior body; a rotating shaft that is rotatably supported within the exterior body; a housing portion that houses an electrical component that enables the rotation shaft to rotate; a rotor disposed outside the housing portion and integrally formed with the rotary shaft; a stator disposed on the outer periphery of the rotor; a rotating disk portion extending radially from an outer circumferential surface of the rotor, A vacuum pump in which exhaust gas flows outside the rotor due to rotation of the rotor, a first opposing surface between the rotor and the stator in the axial direction and having no irregularities, and a second opposing surface between the rotor and the stator in the radial direction and having no irregularities, the second opposing surface comprising the outer circumferential surface of the rotor and the stator in the radial direction, the second opposing surface comprising the outer circumferential surface of the rotor and the stator ...

2. An exterior body, a rotating shaft that is rotatably supported within the exterior body; a housing portion that houses an electrical component that enables the rotation shaft to rotate; a rotor disposed outside the housing portion and integrally formed with the rotary shaft; a stator disposed on the outer periphery of the rotor; a rotating disk portion extending radially from an outer circumferential surface of the rotor, A vacuum pump in which exhaust gas flows outside the rotor due to rotation of the rotor, at least a part of an axially opposing surface between the rotary disk portion and the stator forms a non-contact seal structure that prevents the gas from flowing into the accommodation portion, A vacuum pump characterized in that at least one of the opposing surfaces of the rotary disk portion and the stator is formed as an inclined surface.

3. 3. The vacuum pump according to claim 2, wherein the opposing surfaces of the rotary disk portion and the stator are formed as inclined surfaces, and the inclination angles of the inclined surfaces are the same.

4. the stator further includes a fixed disk portion that faces the rotary disk portion on the upstream side of the gas in the axial direction, 2. The vacuum pump according to claim 1, wherein a first spiral groove for forming an exhaust mechanism is provided on at least one of third opposing surfaces of the rotating disk portion and the fixed disk portion.

5. 5. The vacuum pump according to claim 4, wherein the rotary disk portion constitutes the lowest stage of the exhaust mechanism.

6. An exterior body; a rotating shaft that is rotatably supported within the exterior body; a housing portion that houses an electrical component that enables the rotation shaft to rotate; a rotor disposed outside the housing portion and integrally formed with the rotary shaft; a stator disposed on the outer periphery of the rotor; a rotating disk portion extending radially from an outer circumferential surface of the rotor, A vacuum pump in which exhaust gas flows outside the rotor due to rotation of the rotor, at least a part of a first opposing surface that is smooth and faces the axial direction between the rotary disk portion and the stator and a second opposing surface that is smooth and faces the radial direction between the outer circumferential surface of the rotor and the stator constitutes a non-contact seal structure that prevents the gas from flowing into the accommodation portion, the stator further includes a fixed disk portion that faces the rotary disk portion on the upstream side of the gas in the axial direction, a first spiral groove for constituting an exhaust mechanism is provided on at least one of third opposing surfaces of the rotating disk portion and the fixed disk portion; the rotary disk portion constitutes the lowest stage of the exhaust mechanism, a fourth opposing surface axially opposing a rear surface of the rotary disk portion on the downstream side of the gas;

7. 7. The vacuum pump according to claim 6, wherein the flow straightening portion is a spiral groove portion having a disk shape and a second spiral groove provided on the fourth opposing surface with respect to the rotating disk portion.

8. An exterior body; a rotating shaft that is rotatably supported within the exterior body; a housing portion that houses an electrical component that enables the rotation shaft to rotate; a rotor disposed outside the housing portion and integrally formed with the rotary shaft; a stator disposed on the outer periphery of the rotor; a rotating disk portion extending radially from an outer circumferential surface of the rotor, A vacuum pump in which exhaust gas flows outside the rotor due to rotation of the rotor, at least a part of an axially opposing surface between the rotary disk portion and the stator forms a non-contact seal structure that prevents the gas from flowing into the accommodation portion, the stator further includes a fixed disk portion that faces the rotary disk portion on the upstream side of the gas in the axial direction, a first spiral groove for forming an exhaust mechanism is provided on at least one of the opposing surfaces of the rotating disk portion and the fixed disk portion; the non-contact seal structure is configured by a back surface of the rotary disk portion on the downstream side of the gas and an opposing surface that faces the stator in the axial direction, the rotary disk portion constitutes the lowest stage of the exhaust mechanism, a flow straightening portion having an opposing surface that faces a back surface of the rotary disk portion on the downstream side of the gas in the axial direction, the flow straightening portion is a spiral groove portion having a disk shape and a second spiral groove provided on a surface facing the rotating disk portion, a cylindrical portion that is integral with the rotary disk portion and has an outer circumferential surface that faces the inner circumferential surface of the spiral groove portion, a thread groove provided on at least one of the inner circumferential surface of the spiral groove portion and the outer circumferential surface of the cylindrical portion; The vacuum pump according to claim 1, wherein the non-contact seal structure is formed by a surface of the cylindrical portion on the downstream side of the gas and an opposing surface that faces the stator in the axial direction.

9. the stator is heated by a heating means and includes a flow path defining portion that defines a flow path of the gas; 8. The vacuum pump according to claim 1, wherein the non-contact seal structure is configured such that the first opposing surface is formed by opposing surfaces of the rotary disk portion and the flow path defining portion that are opposed to each other in the axial direction.

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