Vacuum pumps, fixed wings and spacers

Abstract

The present invention provides a vacuum pump that further improves exhaust performance through the design of the fixed wings (inner and outer rims) and spacers provided in the vacuum pump. In a vacuum pump in which the outer diameter of one of the rotating wings is smaller on the exhaust port side, or the inner diameter of one of the rotating wings is larger on the exhaust port side, a tapered surface is provided on at least one of the outer or inner circumferences of the fixed wing positioned above the rotating wing with the smaller outer diameter or the rotating wing with the larger inner diameter. The tapered surface has a descending slope toward the exhaust port. The tapered surface reflects incoming molecules at a right angle, sending them inward, where they collide with the upper rotating wing and are then conveyed to the next exhaust layer.

Description

Technical Field

[0001] The present invention relates to a vacuum pump, a fixed vane, and a spacer, and more particularly to a structure for further improving the exhaust efficiency of a vacuum pump. Background Art

[0002] Conventionally, vacuum pumps such as turbomolecular pumps are widely used, which perform exhaust processing by rotating a rotating portion including a rotor (shaft, rotor), rotor blades, and a rotating cylindrical body at high speed within a housing having an intake port and an exhaust port.

[0003] In these vacuum pumps, exhaust processing is performed by the interaction between multiple layers of rotary blades rotating at high speed and multiple layers of fixed blades fixed to a housing.

[0004] like Figure 30 As shown, the fixed wing 123 used here is composed of an inner rim 600, an outer rim 700, and a plurality of blades 550. The inner rim 600 holds the plurality of blades 550 and holds and fixes the inner side (the rotor side when set), and the outer rim 700 holds and fixes the outer side (the shell side when set). Figure 31 yes Figure 30 FIG. 1 is a partial enlarged view of the dotted circle portion of the fixed wing 123 shown in FIG.

[0005] in addition, Figure 32 A fixed blade 123 of a type without the outer rim 700 as shown (a type in which the blade 550 is held and fixed only by the inner rim 600) is also used.

[0006] Figure 32 This is a diagram of the fixed wing 123 in a state of being divided into half. Figure 33 yes Figure 32 A partial enlarged view of the dotted circle portion.

[0007] However, in this vacuum pump, due to design requirements, there are cases where the outer diameter of one rotor blade of a multi-layer rotor is formed to be smaller on the exhaust port side than on the intake port side, or the inner diameter of one rotor blade of a multi-layer rotor is formed to be larger on the exhaust port side than on the intake port side.

[0008] Figure 34 and Figure 35 It is a diagram for explaining the conventional technology.

[0009] Figure 34 This is a diagram for explaining a conventional turbomolecular pump having an inner rim 600 and an outer rim 700 and a fixed blade 123 ( Figure 30 A cross-sectional view of the case of the type shown in FIG.

[0010] Figure 35 yes Figure 34A partial enlarged view of .

[0011] like Figure 35 As shown, the flow of the exhausted gas is in the direction from the air intake side to the air exhaust side as shown by the arrow.

[0012] If the Figure 35 As shown, the inner rim 600 (outer side) and the outer rim 700 (inner side) on which the fixed blades 123 are arranged are arranged horizontally with respect to the exhaust direction, and no special work is performed with respect to the exhaust operation of the turbomolecular pump.

[0013] Furthermore, the upper surface of the fixed blade spacer, located at the position where the outer diameter of the rotor blade is reduced, has a portion perpendicular to the exhaust direction. This portion is structured to reflect the gas molecules transferred by the upstream rotor blade toward the intake port as is, which is a major factor in degrading exhaust performance.

[0014] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-2692.

[0015] Patent document 2: Japanese Patent Application Laid-Open No. 2018-35718.

[0016] As described above, in the vacuum pumps disclosed in Patent Documents 1 and 2, the outer rim and the inner rim of the fixed blade are arranged horizontally with respect to the exhaust direction of the gas, and do not contribute to the exhaust efficiency.

[0017] In recent years, in vacuum pumps, there has been a demand for further improvement in exhaust efficiency without increasing the size of the pump or the rotation speed of the rotor. Summary of the Invention

[0018] Therefore, an object of the present invention is to provide a vacuum pump in which the exhaust performance is further improved by designing the fixed blades (inner rim and outer rim) and the spacers provided in the vacuum pump.

[0019] The invention described in claim 1 provides a vacuum pump comprising a housing, a rotating shaft, a plurality of rotary blades, and a plurality of fixed blades, the housing having an intake port and an exhaust port, the rotating shaft being rotatably supported within the housing, the plurality of rotary blades being fixed to the rotating shaft so as to rotate together with the rotating shaft, the plurality of fixed blades being fixed relative to the housing and arranged between the rotary blades, the outer diameter of at least one of the plurality of rotary blades being smaller on the exhaust port side than on the intake port side, or the inner diameter of at least one of the plurality of rotary blades being larger on the exhaust port side than on the intake port side, the vacuum pump being characterized in that a tapered surface is provided on the outer periphery or inner periphery of the fixed blade arranged immediately above the rotary blade having the smaller outer diameter or the rotary blade having the larger inner diameter, the tapered surface having a descending slope toward the exhaust port side.

[0020] In the invention described in Technical Solution 2, a vacuum pump described in Technical Solution 1 is provided, characterized in that the aforementioned fixed wing has a plurality of blades arranged radially, an inner rim or an outer rim for holding the plurality of blades, and a conical surface is provided on the outer peripheral surface of the aforementioned inner rim or the inner peripheral surface of the aforementioned outer rim, and the aforementioned conical surface has a descending slope toward the aforementioned exhaust port side.

[0021] In the invention described in Technical Solution 3, a vacuum pump described in Technical Solution 1 is provided, characterized in that the aforementioned fixed wing has a plurality of blades arranged radially, a spacer portion that holds the plurality of blades and positions the aforementioned fixed wing in the height direction, and a conical surface is provided on the inner peripheral surface of the aforementioned spacer portion, and the aforementioned conical surface has a descending slope toward the aforementioned exhaust port side.

[0022] The invention described in claim 4 provides the vacuum pump described in claim 2 or 3, characterized in that the surfaces of the plurality of blades of the fixed blade on the exhaust port side are undercut.

[0023] The invention described in claim 5 provides the vacuum pump described in claim 2 or 3, characterized in that a vertical surface or a tapered surface is provided behind the plurality of blades of the fixed wing.

[0024] In the invention described in Technical Solution 6, a vacuum pump described in Technical Solution 1 is provided, characterized in that a protrusion is provided, the protrusion protruding from the spacer portion to within the range of the height direction of the above-mentioned fixed wing, the spacer portion holds the above-mentioned shell side of the above-mentioned fixed wing and positions the above-mentioned fixed wing in the height direction, and a tapered surface is provided on the inner peripheral surface of the above-mentioned spacer portion and at least a portion of the above-mentioned protrusion, and the above-mentioned tapered surface has a descending slope toward the above-mentioned exhaust port side.

[0025] In the invention described in Technical Solution 7, a fixed wing is provided, wherein the fixed wing is used for a vacuum pump, the vacuum pump comprises a shell, the shell has an air intake port and an air exhaust port, the fixed wing is characterized in that it comprises a plurality of radially arranged blades, an inner rim or an outer rim for holding the plurality of blades, a tapered surface is provided on the outer circumferential surface of the inner rim or the inner circumferential surface of the outer rim, and the tapered surface has a descending slope toward the exhaust port side.

[0026] In the invention described in technical solution 8, a spacer is provided, the spacer being used for a vacuum pump, the vacuum pump comprising a shell, the shell having an air intake port and an air exhaust port, the spacer being characterized in that it comprises a spacer portion, the spacer portion maintaining the shell side when configuring the fixed wing and performing positioning in the height direction of the fixed wing, the fixed wing having a plurality of blades arranged radially, a protrusion being provided, the protrusion protruding from the spacer portion to within the range in the height direction of the fixed wing, a tapered surface being provided on the inner circumferential surface of the spacer portion and at least a portion of the protrusion, the tapered surface having a descending slope toward the exhaust port side.

[0027] Effects of the Invention

[0028] According to the present invention, the shape of the inner rim or outer rim of the fixed blade of the vacuum pump or the spacer is designed, thereby further improving the exhaust performance of the vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a diagram showing a schematic configuration example of a turbomolecular pump according to an embodiment of the present invention.

[0030] Figure 2 This is a diagram showing a circuit diagram of an amplifier circuit used in the embodiment of the present invention.

[0031] Figure 3 This is a timing chart showing control in a case where the current command value is larger than the detected value in the embodiment of the present invention.

[0032] Figure 4 This is a timing chart showing control in a case where the current command value is smaller than the detected value in the embodiment of the present invention.

[0033] Figure 5 This is a diagram showing a schematic configuration example of a turbomolecular pump according to a first embodiment of the present invention.

[0034] Figure 6 yes Figure 5 FIG. 1 is a partially enlarged view of the turbomolecular pump according to the first embodiment shown in FIG.

[0035] Figure 7 This is a diagram showing a fixed blade having a tapered surface provided on the inner rim of the first embodiment A.

[0036] Figure 8 This is a diagram showing a fixed blade having a tapered surface provided on the inner rim of the first embodiment B and having a vertical surface and a circumferential surface.

[0037] Figure 9 This is a diagram showing a fixed blade having tapered surfaces provided on the inner rim and the outer rim of the first embodiment C.

[0038] Figure 10 This is a diagram showing a fixed blade having tapered surfaces provided on the inner rim and the outer rim in the first embodiment D, and having vertical surfaces and circumferential surfaces.

[0039] Figure 11 This figure shows a stationary blade in which tapered surfaces are provided on the inner rim and the outer rim of the first embodiment E, and a tapered surface is also present on the outer rim above (below) the blade.

[0040] Figure 12 This is a diagram showing a stationary blade having tapered surfaces provided on the inner rim and the outer rim in the first embodiment F and having an inner peripheral surface located above (below) the blades.

[0041] Figure 13 This figure shows a stationary blade having tapered surfaces on the inner and outer rims of the first embodiment G, an inner peripheral surface on the outer rim above (below) the blades, and a vertical surface.

[0042] Figure 14 This figure shows a stationary blade having tapered surfaces on the inner and outer rims of the first embodiment H, a tapered surface also existing on the outer rim above (below) the blades, and a vertical surface.

[0043] Figure 15 1. This is a diagram showing a fixing wing having tapered surfaces and flanges on the inner rim and outer rim of the first embodiment I.

[0044] Figure 16 This is a diagram showing a fixing blade having tapered surfaces, flanges, and vertical surfaces provided on the inner rim and outer rim of the first embodiment J.

[0045] Figure 17 This is a partially enlarged view showing a schematic configuration example of a turbomolecular pump according to a second embodiment of the present invention.

[0046] Figure 18 This is a diagram showing a fixed blade having a tapered surface and an inner peripheral surface provided on the outer rim of the second embodiment A.

[0047] Figure 19This is a diagram showing a fixing blade having a tapered surface and an inner peripheral surface and a flange provided on the outer rim of the second embodiment B.

[0048] Figure 20 This is a diagram showing a fixed blade having a tapered surface and an inner peripheral surface provided on the outer rim, and having an inner rim vertical surface and an outer rim vertical surface according to a second embodiment C.

[0049] Figure 21 This is a diagram showing a fixing blade having a tapered surface and an inner peripheral surface and a flange provided on the outer rim of a second embodiment D.

[0050] Figure 22 This is a partially enlarged view of a turbomolecular pump according to a third embodiment.

[0051] Figure 23 This is a partially enlarged view of the turbomolecular pump according to the fourth embodiment.

[0052] Figure 24 This is a diagram showing a fixed blade provided with an inner rim tapered surface on the inner rim of the fourth embodiment A.

[0053] Figure 25 This is a diagram showing a fixed blade provided with an inner rim tapered surface and an inner rim vertical surface on the inner rim of a fourth embodiment B.

[0054] Figure 26 This is a partially enlarged view of the turbomolecular pump according to the fifth embodiment.

[0055] Figure 27 This is a diagram showing the appearance of a fixed blade spacer according to the fifth embodiment A.

[0056] Figure 28 This is a diagram showing the appearance of a fixed blade spacer according to the fifth embodiment B.

[0057] Figure 29 It is a diagram for explaining the angle of the taper.

[0058] Figure 30 This figure shows a conventional fixed-wing aircraft.

[0059] Figure 31 yes Figure 30 A partial enlarged view of the fixed wing shown in FIG.

[0060] Figure 32 This is a diagram showing a conventional fixed blade without an outer rim.

[0061] Figure 33 yes Figure 32 A partial enlarged view of the fixed wing shown in FIG.

[0062] Figure 34This is a diagram showing a schematic configuration example of a conventional turbomolecular pump.

[0063] Figure 35 yes Figure 34 A magnified view of a portion of the turbomolecular pump shown in FIG. DETAILED DESCRIPTION

[0064] (i) Overview of the embodiment

[0065] In this embodiment, in a vacuum pump in which the outer diameter of at least one layer of the multi-layer rotary blades is formed to be a small diameter on the exhaust port side or the inner diameter of at least one layer of the multi-layer rotary blades is formed to be a large diameter on the exhaust port side, a conical surface (inclined surface) is provided on at least one of the outer periphery or the inner periphery of the fixed blade arranged above the rotary blade with the small outer diameter or the rotary blade with the large inner diameter, and the aforementioned conical surface (inclined surface) has a descending slope toward the exhaust port side.

[0066] By providing this tapered surface, molecules entering the exhaust are reflected at a right angle, and the molecules are sent to the inner peripheral side. They are hit by the rotating blades of the upper layer and are sent to the next exhaust layer.

[0067] In this way, the outer peripheral portion or the inner peripheral portion of the fixed blade, which did not contribute to the exhaust in the conventional technology, also contributes to the exhaust, thereby improving the exhaust efficiency of the vacuum pump.

[0068] (ii) Details of implementation methods

[0069] Below, refer to Figures 1 to 29 , a detailed description is given of the preferred embodiments of the present invention.

[0070] (Structure of vacuum pump)

[0071] Figure 1 This diagram schematically illustrates an example of the structure of a turbomolecular pump 100 according to an embodiment of the present invention. Turbomolecular pump 100 has an air intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Furthermore, a rotating body 103 is provided inside outer cylinder 127. Rotating body 103 has multiple radially arranged, multi-layered blades 102 (102a, 102b, 102c, etc.), which serve as turbine blades for sucking and discharging gas. A rotor shaft 113 is mounted at the center of rotating body 103. This rotor shaft 113 is supported in mid-air by, for example, a five-axis magnetic bearing system for position control.

[0072] The upper radial electromagnets 104 are four electromagnets arranged in pairs along the X-axis and the Y-axis. Four upper radial sensors 107 are provided near each of the upper radial electromagnets 104, corresponding to each of the upper radial electromagnets 104. The upper radial sensors 107 utilize, for example, an inductance sensor or an eddy current sensor having a conductive winding. These sensors detect the position of the rotor shaft 113 based on changes in the inductance of the conductive winding that vary with the position of the rotor shaft 113. These upper radial sensors 107 are configured to detect radial displacement of the rotor shaft 113, specifically, the rotating body 103 fixed to the rotor shaft 113, and transmit this information to the control device 200.

[0073] In the control device 200, for example, a compensation loop 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. Figure 2 An amplifier circuit 150 (described later) shown in FIG. 1 performs excitation control on the upper radial electromagnet 104 based on the excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113 .

[0074] The rotor shaft 113 is formed from a high-permeability material (such as iron or stainless steel) and is attracted by the magnetic force of the upper radial electromagnet 104. This adjustment is performed independently in the X-axis and Y-axis directions. Furthermore, the lower radial electromagnet 105 and lower radial sensor 108 are arranged similarly to the upper radial electromagnet 104 and upper radial sensor 107, allowing the lower radial position of the rotor shaft 113 to be adjusted in the same manner as the upper radial position.

[0075] Furthermore, axial electromagnets 106A and 106B are arranged so as to sandwich a disc-shaped metal disk 111 provided on the lower portion of rotor shaft 113. Metal disk 111 is made of a high-permeability material such as iron. An axial sensor 109 is provided to detect axial displacement of rotor shaft 113, and the resulting axial position signal is transmitted to control device 200.

[0076] In addition, in the control device 200, for example, a compensation loop having a PID adjustment function generates respective excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplification circuit 150 performs excitation control on the axial electromagnet 106A and the axial electromagnet 106B respectively based on these excitation control command signals. As a result, the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0077] In this way, the control device 200 appropriately adjusts the magnetic forces exerted by the axial electromagnets 106A and 106B on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and spatially holding it contactlessly. 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.

[0078] Meanwhile, motor 121 includes a plurality of magnetic poles arranged circumferentially to surround rotor shaft 113. Each magnetic pole is controlled by control device 200 so as to rotate rotor shaft 113 via electromagnetic forces acting between the magnetic poles and rotor shaft 113. Furthermore, a rotational speed sensor (not shown) such as a Hall effect element, resolver, or encoder is incorporated into motor 121, and the rotational speed of rotor shaft 113 is detected using detection signals from the rotational speed sensor.

[0079] Furthermore, for example, a phase sensor (not shown) is mounted near the lower radial sensor 108 to detect the rotation phase of the rotor shaft 113. The control device 200 detects the position of the magnetic pole using detection signals from the phase sensor and the rotation speed sensor.

[0080] A plurality of fixed blades 123 (123a, 123b, 123c, etc.) are provided with slight gaps between the rotating blades 102 (102a, 102b, 102c, etc.). The rotating blades 102 (102a, 102b, 102c, etc.) are formed so as to be inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to move exhaust gas molecules downward by collision.

[0081] Furthermore, the fixed blades 123 are similarly formed to be inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged inside the outer cylinder 127, alternating with the layers of the rotary blades 102. Furthermore, the outer peripheral ends of the fixed blades 123 are supported by being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0082] The fixed blade spacer 125 is an annular member made of a metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed blade spacer 125 with a slight 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 entering the air intake port 101 from the cavity side and transferred to the base portion 129 is then delivered to the exhaust port 133.

[0083] Furthermore, due to the purpose of the turbomolecular pump 100, a threaded spacer 131 is provided between the lower portion of the fixed blade spacer 125 and the base 129. The threaded spacer 131 is a cylindrical component made of a metal such as aluminum, copper, stainless steel, iron, or an alloy thereof. Multiple spiral grooves 131a are engraved on its inner circumference. The spiral direction of the grooves 131a is such that exhaust gas molecules are transferred toward the exhaust port 133 as they move in the direction of rotation of the rotor 103. A cylindrical portion 102d extends downward from the lowest portion of the component, which is continuous with the rotor blades 102 (102a, 102b, 102c, etc.) of the rotor 103. The outer circumference of this cylindrical portion 102d is cylindrical and extends toward the inner circumference of the threaded spacer 131, remaining adjacent to the inner circumference of the threaded spacer 131 with a predetermined gap therebetween. The exhaust gas transferred to the thread groove 131 a by the rotary blade 102 and the fixed blade 123 is guided by the thread groove 131 a and sent to the base portion 129 .

[0084] The base 129 is a disc-shaped component that forms the base of the turbomolecular pump 100 and is generally made of a metal such as iron, aluminum, or stainless steel. The base 129 physically holds the turbomolecular pump 100 and also serves as a heat conduction path. Therefore, it is desirable to use a metal such as iron, aluminum, or copper that is rigid and has high thermal conductivity.

[0085] In this structure, when rotor blades 102 and rotor shaft 113 are rotated by motor 121, exhaust gas is drawn from the chamber through intake port 101 by the interaction of rotor blades 102 and fixed blades 123. Exhaust gas drawn from intake port 101 passes between rotor blades 102 and fixed blades 123 and is transferred to base 129. At this time, the temperature of rotor blades 102 rises due to frictional heat generated by contact between the exhaust gas and rotor blades 102, heat conduction from motor 121, and other factors. This heat is then transferred to fixed blades 123 through radiation or conduction through exhaust gas molecules.

[0086] The fixed blade spacers 125 are joined to each other at their outer circumferences, and transfer heat received by the fixed blades 123 from the rotary blades 102 , frictional heat generated when exhaust gas contacts the fixed blades 123 , and the like to the outside.

[0087] In the above description, the threaded spacer 131 is arranged on the outer periphery of the cylindrical portion 102d of the rotating body 103, and the threaded groove 131a is engraved on the inner peripheral surface of the threaded spacer 131. However, there is also a case where the threaded groove is engraved on the outer peripheral surface of the cylindrical portion 102d, and a spacer having a cylindrical inner peripheral surface is arranged around the outer peripheral surface.

[0088] In addition, depending on the purpose of the turbomolecular pump 100, there is also the following situation: the electrical equipment part is covered with the help of the stator column 122, so that the gas sucked from the intake port 101 will not enter the electrical equipment part composed of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A, 106B, the axial sensor 109, etc., and the stator column 122 is maintained at a predetermined pressure with the help of flushing gas.

[0089] In this case, a pipe (not shown) is provided at the base portion 129, and flushing gas is introduced through this pipe. The introduced flushing gas passes through the 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, and is then discharged to the exhaust port 133.

[0090] Here, the turbomolecular pump 100 requires control based on the inherent parameters (for example, a number of characteristics corresponding to the model) that are determined and adjusted separately for each model. In order to store these control parameters, the turbomolecular pump 100 is equipped with an electronic circuit unit 141 in its main body. The electronic circuit unit 141 is composed of a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting the components. The electronic circuit unit 141 is housed below the rotational speed sensor (not shown in the figure), for example, near the center of the base unit 129, and is closed by an airtight bottom cover 145. The base unit 129 constitutes the lower part of the turbomolecular pump 100.

[0091] However, in the semiconductor manufacturing process, the process gas introduced into the chamber contains substances that solidify when their pressure exceeds a predetermined value or their temperature drops below a predetermined value. Within the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. If the process gas's pressure rises above a predetermined value or its temperature drops below a predetermined value while being transferred from the intake port 101 to the exhaust port 133, the process gas solidifies and accumulates within the turbomolecular pump 100.

[0092] For example, when SiCl4 is used as the process gas in an Al etching device, it can be seen from the vapor pressure curve that low vacuum (760[torr]~10 -2When the temperature is high (approximately 20°C) and the pressure is low (approximately 20°C), solid products (such as AlCl3) precipitate and accumulate inside the turbomolecular pump 100. Consequently, when process gas precipitates accumulate inside the turbomolecular pump 100, the accumulation narrows the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. Furthermore, the aforementioned products are prone to solidification and accumulation in high-pressure areas near the exhaust port and the threaded spacer 131.

[0093] Therefore, in order to solve this problem, in the past, a heater not shown in the figure and a ring-shaped water-cooling pipe 149 were wound around the outer periphery of the base part 129, and a temperature sensor not shown in the figure (such as a thermistor) was buried in the base part 129, so that the temperature of the base part 129 was maintained at a constant higher temperature (set temperature) based on the signal of the temperature sensor, and the heating of the heater and the cooling of the water-cooling pipe 149 were controlled (hereinafter referred to as TMS. TMS; Temperature Management System).

[0094] Next, the turbo molecular pump 100 configured as described above will be described with respect to the amplifier circuit 150 for controlling the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B. Figure 2 A circuit diagram of the amplifier circuit 150 is shown in FIG.

[0095] Figure 2 In the embodiment, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 and the like is connected to the positive electrode 171a of the power supply 171 via the transistor 161, and the other end is connected to the negative electrode 171b of the power supply 171 via the current detection circuit 181 and the transistor 162. Furthermore, the transistors 161 and 162 are so-called power field-effect transistors, and have a structure in which a diode is connected between their source and drain.

[0096] At this time, transistor 161 has its diode cathode terminal 161a connected to anode 171a and its anode terminal 161b connected to one end of electromagnet winding 151. Furthermore, transistor 162 has its diode cathode terminal 162a connected to current detection circuit 181 and its anode terminal 162b connected to cathode 171b.

[0097] On the other hand, the cathode terminal 165a of the current regeneration diode 165 is connected to one end of the electromagnet winding 151, and the anode terminal 165b is connected to the negative electrode 171b. Similarly, the cathode terminal 166a of the current regeneration diode 166 is connected to the positive electrode 171a, and the anode terminal 166b is connected to the other end of the electromagnet winding 151 via the current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall effect sensor-type current sensor and a resistor element.

[0098] The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled in five axes and there are ten electromagnets 104, 105, 106A, and 106B in total, the same amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0099] Furthermore, the amplification control circuit 191 is constituted by, for example, a digital signal processor unit (hereinafter referred to as a DSP unit) not shown in the figure of the control device 200 , and switches the transistors 161 and 162 on and off.

[0100] Amplification control circuit 191 compares the current value detected by current detection circuit 181 (a signal reflecting this current value is referred to as current detection signal 191c) with a predetermined current command value. Based on this comparison result, it determines the pulse width (pulse width times Tp1 and Tp2) generated within one cycle of PWM control, namely, control period Ts. Consequently, amplification control circuit 191 outputs gate drive signals 191a and 191b having the corresponding pulse widths to the gate terminals of transistors 161 and 162.

[0101] Furthermore, when the rotational speed of the rotating body 103 passes through a resonance point during accelerated operation or when external disturbances occur during constant speed operation, high-speed and powerful position control of the rotating body 103 is required. Therefore, in order to enable a rapid increase (or decrease) in the current flowing to the electromagnet winding 151, a high voltage of, for example, approximately 50 V is used as the power supply 171. Furthermore, to stabilize the power supply 171, a capacitor is typically connected between the positive electrode 171a and the negative electrode 171b of the power supply 171 (not shown).

[0102] In this configuration, when both the 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.

[0103] Furthermore, when one of transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is maintained. This flow of flywheel current through amplifier circuit 150 reduces hysteresis losses in amplifier circuit 150, thereby keeping overall circuit power consumption low. Furthermore, by controlling transistors 161 and 162 in this manner, high-frequency noise such as high-pitched waves generated in turbomolecular pump 100 can be reduced. Furthermore, by measuring this flywheel current via current detection circuit 181, the electromagnet current iL flowing through electromagnet winding 151 can be detected.

[0104] That is, when the detected current value is smaller than the current command value, Figure 3 As shown, during a control period Ts (e.g., 100 μs), both transistors 161 and 162 are turned on once for a time corresponding to a pulse width Tp1. Therefore, during this period, the electromagnet current iL 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 and 162.

[0105] On the other hand, if the detected current value is larger than the current command value, Figure 4 As shown, during the control period Ts, both transistors 161 and 162 are turned off once for a period of time corresponding to the pulse width Tp2. Therefore, during this period, the electromagnet current iL decreases from the negative electrode 171b to the positive electrode 171a to a current value iLmin (not shown) that can be regenerated via the diodes 165 and 166.

[0106] In either case, after the pulse width time Tp1 or Tp2 has elapsed, one of the transistors 161 and 162 is turned on. Therefore, during this period, the flywheel current in the amplifier circuit 150 is maintained.

[0107] (First embodiment)

[0108] Next, refer to Figures 5 to 16 , the first embodiment is described.

[0109] Figure 5 1 is a diagram showing a schematic configuration example of a turbomolecular pump according to a first embodiment. Figure 6 yes Figure 5 FIG. 1 is a partially enlarged view of the turbomolecular pump according to the first embodiment shown in FIG.

[0110] In the first embodiment, tapered surfaces (inner rim tapered surface 610 and outer rim tapered surface 710 ) having a descending slope toward the exhaust port are provided on the inner rim 600 or the outer rim 700 or both of the fixed blades 123 .

[0111] The tapered surface is provided at a location where the outer diameter of one rotor blade in the multi-layered rotor blades is smaller on the exhaust port side, or where the inner diameter of one rotor blade in the multi-layered rotor blades is larger on the exhaust port side. A fixed blade 123 with a tapered surface is disposed between these rotor blades.

[0112] Figure 7 This is a diagram showing a fixed blade 123 having a tapered surface provided on the inner rim of the first embodiment A.

[0113] As shown in the figure, inner rim 600 is provided with an inner rim tapered surface 610, which slopes downward toward the exhaust port. When incoming molecules collide with this inner rim tapered surface 610, they are reflected at a right angle, collide with the upper rotor blades, and are carried to the lower stage. From this perspective, the provision of inner rim tapered surface 610 also on inner rim 600 contributes to the exhaust function. As can be seen from the figure, the blades 550 of the fixed blades 123 are held and fixed by the inner rim 600 and outer rim 700.

[0114] Figure 8 This figure shows a fixing blade 123 having a tapered surface provided on the inner rim of the first embodiment B. The fixing blade 123 of the first embodiment B is formed with an inner rim vertical surface 620 and an inner rim circumferential surface 630 .

[0115] The fixing wings 123 are made of, for example, aluminum and are manufactured as a casting using a mold or by cutting.

[0116] When manufacturing as a casting using a mold, the product must be extracted from the mold, so an inner rim vertical surface 620 is provided. On the lower side of the blade 550, at the location where the inner rim vertical surface 620 is formed, an inner rim circumferential surface 630 is formed, which is parallel to the outer rim 700.

[0117] Figure 9 This figure shows a fixed blade 123 having tapered surfaces on the inner and outer rims of the first embodiment C. As shown in this figure, not only the inner rim 600 but also the outer rim 700 is provided with an outer rim tapered surface 710, which has a descending slope toward the exhaust port.

[0118] In the first embodiment C, not only the inner rim 600 but also the outer rim 700 contributes to the exhaust function.

[0119] In the first embodiment C, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0120] Figure 10This is a diagram showing a fixing blade 123 having tapered surfaces, vertical surfaces, and circumferential surfaces provided at the inner rim and the outer rim in the first embodiment D.

[0121] As in the first embodiment B, when manufacturing as a casting using a mold, the product needs to be extracted from the mold, so an outer rim vertical surface 720 is provided. On the lower side of the blade 550, at the location where the outer rim vertical surface 720 is formed, an outer rim circumferential surface 730 is formed that is parallel to the inner rim 600.

[0122] Figure 11 (a) and (b) show the fixed blade 123 having tapered surfaces provided on the inner rim and the outer rim of the first embodiment E, and also having a tapered surface on the upper side (lower side) of the blade on the outer rim.

[0123] The inner rim 600 of the first embodiment E has the same shape as that of the first embodiment A and embodiment C, but the structure of the outer rim 700 is different from that of the first embodiment C. That is, Figure 11 In the embodiment shown in (a), the outer rim tapered surface 710 is formed to a position above the surface of the blade 550 , and a surplus portion 740 exists.

[0124] on the other hand, Figure 11 In the embodiment shown in (b), the outer rim tapered surface 710 is formed to a position below the back surface of the blade 550 , and a surplus portion 740 exists.

[0125] The presence of the excess portion 740 makes it easier to define the axial dimension of the fixed blade 123. That is, the height direction can be adjusted within a range where the blade 550 does not interfere.

[0126] In the first embodiment E, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0127] In addition, since there is no vertical surface in the first embodiment E, it is manufactured by cutting.

[0128] Figure 12 This figure shows a fixed blade 123 having tapered surfaces provided on the inner rim and the outer rim in the first embodiment F and having an inner peripheral surface located above (below) the blades.

[0129] The inner rim 600 of the first embodiment F has the same shape as in the first embodiment A and embodiment C, but the structure of the outer rim 700 differs from that of the first embodiment C. Specifically, an outer rim inner circumferential surface 760 is formed above (below) the surface of the blades 550. Unlike the outer rim tapered surface 710, the outer rim inner circumferential surface 760 is parallel to the axial direction of the turbomolecular pump 100.

[0130] By providing the outer rim inner peripheral surface 760 and adjusting the axial dimension, the fixed blade 123 can be positioned in the axial direction when installed in the turbomolecular pump 100 .

[0131] In the first embodiment F, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the tapered surface 710 may be provided only on the outer rim 700 .

[0132] In addition, since there is no vertical surface in the first embodiment F, it is manufactured by cutting.

[0133] Figure 13 This figure shows a fixed blade 123 having tapered surfaces on the inner and outer rims, an inner circumferential surface on the outer rim above (below) the blades, and a vertical surface. This embodiment G differs from the first embodiment F in that an inner rim vertical surface 620 and an outer rim vertical surface 720 are provided.

[0134] By providing the outer rim inner peripheral surface 760 and adjusting the axial dimension, the fixed blade 123 can be positioned in the axial direction when installed in the turbomolecular pump 100 .

[0135] In the first embodiment G, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0136] Figure 14 Figures (a) and (b) show a fixed blade 123 in the first embodiment H, in which tapered surfaces are provided on the inner and outer rims, a tapered surface is also provided on the outer rim above (below) the blades, and a vertical surface is provided. (a) is an external view as viewed from above, and (b) is an external view as viewed from below.

[0137] This embodiment differs from the first embodiment E in that an inner rim vertical surface 620 and an outer rim vertical surface 720 are provided.

[0138] The presence of the remaining portion 740 makes it easier to define the axial dimension of the fixed blade 123 .

[0139] In the first embodiment H, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the tapered surface 710 may be provided only on the outer rim 700 .

[0140] Figure 15 1. This is a diagram showing a fixing wing 123 having tapered surfaces and flanges provided at the inner rim and the outer rim of the first embodiment I.

[0141] In this embodiment I, a flange 750 is provided that protrudes outward (toward the outer cylinder 127 when provided) from the outer rim 700.

[0142] The flange 750 can be used to position and retain the fixed blade 123 in the axial direction. That is, by adjusting the thickness (axial height) of the flange 750, the fixed blade 123 can be positioned in the axial direction, and by clamping the flange 750, it can be fixed to the outer cylinder 127.

[0143] In the first embodiment I, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0144] In addition, since there is no vertical surface in the first embodiment I, it is manufactured by cutting.

[0145] Figure 16 This figure shows a fixing blade 123 provided with tapered surfaces on the inner rim and the outer rim, an inner rim vertical surface and an outer rim vertical surface, and a flange in the first embodiment J.

[0146] In this embodiment J, similarly to the embodiment I, a flange 750 is provided that protrudes outward (toward the outer cylinder 127 when provided) from the outer rim 700 .

[0147] The flange 750 can be used to position and retain the fixed blade 123 in the axial direction. That is, by adjusting the thickness (axial height) of the flange 750, the fixed blade 123 can be positioned in the axial direction, and by clamping the flange 750, it can be fixed to the outer cylinder 127.

[0148] This embodiment J differs from the first embodiment I in that an inner rim vertical surface 620 and an outer rim vertical surface 720 are provided.

[0149] In the first embodiment J, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0150] (Second embodiment)

[0151] Next, refer to Figures 17 to 21 , the second embodiment is described.

[0152] Figure 17 This is a partially enlarged view of the turbomolecular pump according to the second embodiment.

[0153] In this second embodiment, the outer rim 700 of the fixed blade 123 is provided with an outer rim tapered surface 710 that slopes downward toward the exhaust port, and an outer rim inner circumferential surface 760. Specifically, the outer rim tapered surface 710 and the outer rim inner circumferential surface 760 coexist on the outer rim 700. The inner rim 600 is otherwise the same as in the first embodiment.

[0154] Figure 18 This is a diagram showing a fixed blade 123 having a tapered surface and an inner peripheral surface provided on the outer rim of the second embodiment A.

[0155] The outer rim tapered surface 710 is located at a position corresponding to the blades 550. An outer rim inner peripheral surface 760 is provided below the outer rim tapered surface 710. The outer rim inner peripheral surface 760 is parallel to the axial direction of the turbomolecular pump 100 without being inclined.

[0156] The positioning of the fixed blade 123 can be performed by adjusting the height direction of the outer rim inner peripheral surface 760. Since the blade 550 does not exist at the position corresponding to the outer rim inner peripheral surface 760, adjustment can be performed easily.

[0157] In the second embodiment A, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0158] In addition, since there is no vertical surface in the second embodiment A, it is manufactured by cutting.

[0159] Figure 19 This figure shows a fixing blade 123 having a tapered surface and an inner peripheral surface and a flange provided on the outer rim of the second embodiment B.

[0160] The outer rim tapered surface 710 is arranged at a position corresponding to the blade 550. An outer rim inner peripheral surface 760 is provided at a lower portion thereof.

[0161] The second embodiment B differs from the second embodiment A in that a flange 750 is provided that protrudes toward the outside of the outer rim 700 (toward the outer cylinder 127 when provided).

[0162] The flange 750 can be used to position and retain the fixed blade 123 in the axial direction. That is, by adjusting the thickness (axial height) of the flange 750, the fixed blade 123 can be positioned in the axial direction, and by clamping the flange 750, it can be fixed to the outer cylinder 127.

[0163] In the second embodiment B, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0164] In addition, since there is no vertical surface in the second embodiment B, it is manufactured by cutting.

[0165] Figure 20 This figure shows a fixing blade 123 provided with a tapered surface and an inner peripheral surface at the outer rim, and provided with an inner rim vertical surface and an outer rim vertical surface in a second embodiment C.

[0166] The outer rim tapered surface 710 is arranged at a position corresponding to the blade 550. An outer rim inner peripheral surface 760 is provided at a lower portion thereof.

[0167] The difference between this embodiment C and the second embodiment A is that when manufacturing as a casting using a mold, it is necessary to extract the product from the mold, so the inner rim vertical surface 630 and the outer rim vertical surface 720 are provided.

[0168] In the second embodiment C, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0169] Figure 21 This is a diagram showing a fixing blade 123 having a tapered surface and an inner peripheral surface and a flange provided on the outer rim according to the second embodiment D.

[0170] The outer rim tapered surface 710 is arranged at a position corresponding to the blade 550. An outer rim inner peripheral surface 760 is provided at a lower portion thereof.

[0171] The difference between the second embodiment D and the second embodiment C is that a flange 750 is provided that protrudes toward the outside of the outer rim 700 (toward the outer cylinder 127 when provided).

[0172] The flange 750 can be used to position and retain the fixed blade 123 in the axial direction. That is, by adjusting the thickness (axial height) of the flange 750, the fixed blade 123 can be positioned in the axial direction, and by clamping the flange 750, it can be fixed to the outer cylinder 127.

[0173] In the second embodiment D, the tapered surfaces ( 610 , 710 ) are provided on both the inner rim 600 and the outer rim 700 . However, the outer rim tapered surface 710 may be provided only on the outer rim 700 .

[0174] (Third embodiment)

[0175] Next, refer to Figure 22, the third embodiment is described.

[0176] Figure 22 This is a partially enlarged view of a turbomolecular pump according to a third embodiment.

[0177] In the third embodiment, the fixing blades 123 used in the first embodiment are arranged in opposite directions or in the same direction. Furthermore, at least the fixing blades 123 of the final layer are arranged in opposite directions.

[0178] By disposing the fixing wings 123 in this manner, products (fixing wings 123) of the same size can be used in combination, thereby reducing manufacturing costs.

[0179] Furthermore, since the outer rim tapered surface 710 is continuously connected, no gap with respect to the spacer can be provided.

[0180] (Fourth embodiment)

[0181] Next, refer to Figures 23 to 25 , the fourth embodiment is described.

[0182] Figure 23 This is a partially enlarged view of the turbomolecular pump according to the fourth embodiment.

[0183] In this fourth embodiment, an inner rim tapered surface 610 having a descending slope toward the exhaust port is provided on the inner rim 600 of the stationary blade 123. Specifically, the inner rim tapered surface 610 is provided on the inner rim 600, which is located at a position where the root diameter of the blades 550 of the upstream stationary blade 123 is smaller than the root diameter of the blades 550 of the downstream stationary blade 123.

[0184] Figure 24 The fourth embodiment A shows a fixed blade 123 provided with an inner rim tapered surface 610 at the inner rim 600. Figure 24 The inner rim 600 shown in FIG. 6 does not have an inner rim vertical surface 620 and is therefore manufactured by cutting.

[0185] Figure 25 The fourth embodiment B shows a fixing blade 123 provided with an inner rim tapered surface 610 and an inner rim vertical surface at the inner rim 600. Figure 25 The inner rim 600 shown in FIG. 1 is manufactured by casting using a mold because of the presence of the inner rim vertical surface 620 .

[0186] Figure 24 and Figure 25 In both cases, the fixing blades 123 of the type without the outer rim 70 are shown. However, this fourth embodiment can also be applied to the fixing blades 123 of the type with the outer rim 700.

[0187] (Fifth embodiment)

[0188] Next, refer to Figures 26 to 28 , the fifth embodiment is described.

[0189] Figure 26 This is a partially enlarged view of the turbomolecular pump according to the fifth embodiment.

[0190] The fifth embodiment relates to a fixed blade spacer 800 including a fixed blade spacer portion 870 that positions the fixed blades 123 in the height direction by holding the outer frame 127 side.

[0191] Figure 27 (Fifth Implementation A) and Figure 28 (Fifth Embodiment B) illustrates the external appearance of the stator spacer 800. As shown in these figures, the stator spacer 800 is provided with a protrusion 860 that protrudes in the height direction from the spacer portion 870 to the stator 123. A stator spacer tapered surface 810 with a downward slope toward the exhaust port is formed on at least a portion of the inner circumferential surface 830 of the stator spacer portion 870 and the protrusion 860. The area within which the inner circumferential surface 830 of the stator spacer portion 870 and the protrusion 860 protrude in the height direction of the stator 123 is also defined as the "outer circumference of the stator."

[0192] Between the protrusions 860 , there are provided blade fitting grooves 820 into which the blade 550 of the fixed wing 123 is fitted and held when installed.

[0193] Figure 28 The fixed wing spacer 800 shown in FIG is further provided with a fixed wing spacer flange 850. The fixed wing spacer flange 850 is used to position the fixed wing spacer 800 in the height direction or to clamp it, thereby holding and fixing the fixed wing spacer 800.

[0194] (angle about the cone)

[0195] The angles of the tapered surfaces in the above-mentioned embodiments 1 to 5 will be described.

[0196] The angle of the tapered surface is not particularly limited as long as it is a tapered surface (inclined surface) having a downward slope toward the exhaust port side.

[0197] Figure 29 (a) is a cross-sectional view of the fixed blade 123 corresponding to the first embodiment H. In the example shown in this figure, a tapered surface is provided on the fixed blade 123 at an angle of a line (imaginary line) connecting the inner diameter lower end A of the fixed blade spacer 125 and the inner diameter upper end B of the fixed blade spacer 125.

[0198] also, Figure 29 (b) is a cross-sectional view of the fixed wing 123 corresponding to the second embodiment D. In the example shown in this figure, a tapered surface is provided on the fixed wing 123 at a certain angle between the intersection point H of a perpendicular line extending from the tip X of the upper rotor 102 to the lower fixed wing 123 and a line (imaginary line) connecting points (1) (the root of the blade 550 of the fixed wing 123) or (2) (the inner circumferential lower surface of the fixed wing 123).

[0199] In this way, the angle of the tapered surface can be various angles and can be appropriately determined according to various situations.

[0200] Furthermore, in each embodiment, not only a tapered surface but also a gently curved surface may be used.

[0201] Furthermore, the embodiments and modifications of the present invention may be combined as needed.

[0202] Furthermore, the present invention can be modified in various ways without departing from the spirit of the present invention, and the present invention obviously also covers such modifications.

[0203] Description of Reference Numerals

[0204] 100 turbomolecular pump

[0205] 101 Inlet

[0206] 102 Rotary Wing

[0207] 103 Rotating Body

[0208] 113 rotor shaft

[0209] 123 Fixed-wing

[0210] 125 Fixed wing spacer

[0211] 127 outer cylinder

[0212] 129 base

[0213] 133 exhaust port

[0214] 200 Control Device

[0215] 550 blades

[0216] 600 inner rim

[0217] 610 inner rim cone

[0218] 620 Inner rim vertical surface

[0219] 630 inner rim circumference

[0220] 700 outer rim

[0221] 710 outer rim cone

[0222] 720 outer rim vertical surface

[0223] 730 outer rim circumference

[0224] 740 remaining

[0225] 750 flange

[0226] 760 inner circumference of outer rim

[0227] 800 Fixed Wing Spacer

[0228] 810 fixed wing spacer cone

[0229] 820 blade fitting groove

[0230] 830 Inner surface of fixed wing spacer

[0231] 850 Fixed Wing Spacer Flange

[0232] 860 protrusion

[0233] 870 Fixed wing spacer section.

Claims

1. A vacuum pump comprising a housing, a rotating shaft, a plurality of rotating blades, and a plurality of fixed blades. The shell has an air intake and an air exhaust port. The rotating shaft is rotatably supported inside the housing. The multi-layered rotor blades are fixed to the rotating shaft and can rotate together with the rotating shaft. The multi-layer fixed wings are fixed relative to the shell and are arranged between the rotating wings. The outer diameter of at least one of the plurality of rotor blades is formed so that the outer diameter on the exhaust port side is smaller than that on the intake port side, or the inner diameter of at least one of the plurality of rotor blades is formed so that the inner diameter on the exhaust port side is larger than that on the intake port side. The vacuum pump is characterized in that The outer and inner circumferences of the fixed wing arranged above the aforementioned rotating wing with a small outer diameter or the aforementioned rotating wing with a large inner diameter are provided with tapered surfaces, and the tapered surfaces have a descending slope toward the exhaust port side. The fixed blade has a plurality of blades arranged radially, an inner rim and an outer rim for holding the plurality of blades. The tapered surface is provided on the outer peripheral surface of the inner rim and the inner peripheral surface of the outer rim.

2. The vacuum pump according to claim 1, wherein The fixed blade has a plurality of blades arranged radially, and a spacer portion for holding the plurality of blades and positioning the fixed blade in a height direction. A tapered surface is provided on the inner peripheral surface of the spacer portion, and the tapered surface has a descending slope toward the exhaust port side.

3. The vacuum pump according to claim 2, wherein The undercut reaches the surface of the plurality of blades of the fixed blade on the exhaust port side.

4. The vacuum pump according to claim 2, wherein A vertical surface or a conical surface is provided behind the plurality of blades of the fixed wing.

5. The vacuum pump according to claim 1, wherein A protrusion is provided, the protrusion protruding from the spacer portion to within the range of the height direction of the fixed wing, the spacer portion holding the shell side of the fixed wing and performing the height direction positioning of the fixed wing, A tapered surface is provided on an inner peripheral surface of the spacer portion and at least a portion of the protruding portion, and the tapered surface has a descending slope toward the exhaust port side.

6. A fixed wing for a vacuum pump, wherein the vacuum pump comprises a housing, the housing having an air intake port and an air exhaust port, wherein the fixed wing is characterized in that: The invention comprises a plurality of blades arranged radially, an inner rim and an outer rim for holding the plurality of blades, Tapered surfaces are provided on the outer circumferential surface of the inner rim and the inner circumferential surface of the outer rim, and the tapered surfaces have a descending slope toward the exhaust port side.

Images