CN115803530A

CN115803530A - Vacuum pump, stationary vane, and spacer

Info

Publication number: CN115803530A
Application number: CN202180049707.XA
Authority: CN
Inventors: 三轮田透; 时永伟
Original assignee: Edwards Japan Ltd
Current assignee: Edwards Japan Ltd
Priority date: 2020-08-21
Filing date: 2021-07-30
Publication date: 2023-03-14
Also published as: KR20230050310A; IL300054A; US20230323890A1; EP4202227A1; WO2022038996A1; JP2022035881A

Abstract

The invention provides a vacuum pump, which further improves the exhaust performance by designing a fixed wing (an inner rim ring and an outer rim ring) and a spacer arranged on the vacuum pump. In a vacuum pump in which the outer diameter of one of the rotary vanes is formed to be small on the exhaust port side or the inner diameter of one of the rotary vanes is formed to be large on the exhaust port side, a tapered surface having a downward slope toward the exhaust port side is provided on at least one of the outer peripheral portion or the inner peripheral portion of the stationary vane disposed immediately after the rotary vane having the small outer diameter or the rotary vane having the large inner diameter. The molecules are reflected at a right angle by the tapered surface when entering, are sent to the inner peripheral side, are impacted by the upper rotating wing, and are sent to the next exhaust layer.

Description

Vacuum pump, stationary vane, and spacer

Technical Field

The present invention relates to a vacuum pump, a stationary vane, and a spacer, and more particularly, to a structure for further improving the exhaust efficiency of a vacuum pump.

Background

Conventionally, vacuum pumps such as turbo molecular pumps, which perform an exhaust treatment by rotating a rotating part including a rotor part (shaft, rotor) and rotating blades, and a rotating cylindrical body at a high speed inside a casing having an air inlet and an air outlet, have been widely used.

In these vacuum pumps, exhaust gas treatment is performed by the interaction of a multi-layer rotary vane rotating at a high speed and a multi-layer fixed vane fixed to a casing.

As shown in fig. 30, the fixing vane 123 used here is composed of an inner rim 600, an outer rim 700, and a plurality of vanes 550, the inner rim 600 holds and fixes the plurality of vanes 550 to the inside (rotor side at the time of installation), and the outer rim 700 holds and fixes the outside (shell side at the time of installation). Fig. 31 is a partially enlarged view of a broken-line circular portion of the stationary blade 123 shown in fig. 30.

Also, as shown in fig. 32, a fixing wing 123 of a type in which the outer rim 700 does not exist (a type in which the vane 550 is held and fixed only by the inner rim 600) is used.

Fig. 32 is a view of the stationary blade 123 in a half-divided state. Fig. 33 is a partial enlarged view of a dotted circle portion of fig. 32.

However, in this vacuum pump, the following may occur due to design requirements: the outer diameter of one of the multi-layer rotary blades is formed to be smaller on the exhaust port side than on the intake port side, or the inner diameter of one of the multi-layer rotary blades is formed to be larger on the exhaust port side than on the intake port side.

Fig. 34 and 35 are diagrams for explaining the related art.

Fig. 34 is a cross-sectional view for explaining a case where a fixed vane 123 (of the type shown in fig. 30) having an inner rim 600 and an outer rim 700 of a conventional turbomolecular pump is used.

Fig. 35 is a partially enlarged view of fig. 34.

As shown in fig. 35, the flow of the discharged gas is in the direction from the air inlet side to the air outlet side as indicated by the arrow.

As shown in fig. 35, the inner rim 600 (outer side) and the outer rim 700 (inner side) on which the fixed vane 123 is disposed are disposed horizontally with respect to the exhaust direction, and no special operation is performed for the exhaust operation of the turbo molecular pump.

Further, the upper surface of the stationary vane spacer at the reduced diameter position of the outer diameter of the rotary vane has a portion which becomes a plane perpendicular to the exhaust direction, and is a structure in which gas molecules transferred by the upstream rotary vane are reflected toward the intake port side as they are, which is a factor of reducing the exhaust performance.

Patent document 1: japanese patent laid-open No. 2007-2692.

Patent document 2: japanese unexamined patent publication No. 2018-35718.

As described above, in the vacuum pumps disclosed in patent documents 1 and 2, the outer rim and the inner rim of the fixed vane are disposed horizontally with respect to the exhaust direction of the gas, and do not contribute to the exhaust efficiency.

In recent years, in vacuum pumps, it has been required to further improve the exhaust efficiency without increasing the size of the pump or the rotational speed of the rotor portion.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a vacuum pump in which exhaust performance is further improved by designing fixing vanes (an inner rim and an outer rim) and spacers provided in the vacuum pump.

In the invention described in claim 1, there is provided a vacuum pump comprising a casing having an air inlet and an air outlet, a rotary shaft rotatably supported in the casing, a plurality of rotary vanes fixed to the rotary shaft and rotatable together with the rotary shaft, and a plurality of fixed vanes fixed to the casing and disposed between the rotary vanes, wherein at least one of the plurality of rotary vanes has an outer diameter smaller than that of the air inlet, and an inner diameter larger than that of the air inlet, and wherein the rotary vane having a smaller outer diameter or the rotary vane having a larger inner diameter has a tapered surface at an outer peripheral portion or an inner peripheral portion thereof, and the fixed vane disposed above the air inlet has a downward slope toward the air outlet.

The invention described in claim 2 provides the vacuum pump described in claim 1, wherein the stationary vane includes a plurality of radially arranged vanes, and an inner rim or an outer rim that holds the plurality of vanes, and wherein a tapered surface is provided on an outer peripheral surface of the inner rim or an inner peripheral surface of the outer rim, and the tapered surface has a downward slope toward the exhaust port.

The invention described in claim 3 provides the vacuum pump described in claim 1, wherein the stationary blade has a plurality of blades radially arranged, and a spacer portion that holds the plurality of blades and performs positioning in a height direction of the stationary blade, and wherein a tapered surface having a descending slope toward the exhaust port side is provided on an inner circumferential surface of the spacer portion.

The invention described in claim 4 provides the vacuum pump described in claim 2 or claim 3, wherein the vacuum pump is undercut to the exhaust port side surfaces of the plurality of vanes of the stationary blade.

The invention described in claim 5 provides the vacuum pump described in claim 2 or claim 3, wherein a vertical surface or a tapered surface is provided behind the plurality of blades of the stationary blade.

The invention described in claim 6 provides the vacuum pump described in claim 1, wherein a projecting portion is provided, the projecting portion projecting from a spacer portion into a range in a height direction of the fixed vane, the spacer portion holding the shell side of the fixed vane and positioning the fixed vane in the height direction, and tapered surfaces having a descending slope toward the exhaust port side are provided on an inner peripheral surface of the spacer portion and at least a part of the projecting portion.

The invention described in claim 7 provides a stationary vane used for a vacuum pump including a casing having an intake port and an exhaust port, the stationary vane including a plurality of radially arranged vanes and an inner rim or an outer rim for holding the plurality of vanes, wherein a tapered surface is provided on an outer peripheral surface of the inner rim or an inner peripheral surface of the outer rim, and the tapered surface has a descending slope toward the exhaust port.

The invention described in claim 8 provides a spacer used for a vacuum pump including a housing having an air inlet and an air outlet, wherein the spacer includes a spacer portion that holds the housing side and positions the stationary blade in the height direction when the stationary blade is disposed, the stationary blade includes a plurality of radially disposed blades, and a protrusion is provided, the protrusion protrudes from the spacer portion to the stationary blade in the height direction, a tapered surface is provided on an inner peripheral surface of the spacer portion and at least a part of the protrusion, and the tapered surface has a downward slope toward the air outlet side.

Effects of the invention

According to the present invention, the shape of the inner rim or the outer rim or the spacer of the fixed vane of the vacuum pump is designed, whereby the exhaust performance of the vacuum pump can be further improved.

Drawings

Fig. 1 is a diagram showing a schematic configuration example of a turbomolecular pump according to an embodiment of the present invention.

Fig. 2 is a circuit diagram showing an amplification circuit used in the embodiment of the present invention.

Fig. 3 is a timing chart showing control in the case where the current command value is larger than the detection value in the embodiment of the present invention.

Fig. 4 is a timing chart showing control in the case where the current command value is smaller than the detection value in the embodiment of the present invention.

Fig. 5 is a diagram showing a schematic configuration example of a turbomolecular pump according to embodiment 1 of the present invention.

Fig. 6 is a partially enlarged view of the turbomolecular pump according to embodiment 1 shown in fig. 5.

Fig. 7 is a view showing a stationary blade provided with a tapered surface at an inner rim according to embodiment 1a.

Fig. 8 is a view showing a stationary blade provided with a tapered surface and a vertical surface and a circumferential surface at an inner rim of embodiment 1B.

Fig. 9 is a view showing a stationary vane provided with tapered surfaces on an inner rim and an outer rim in embodiment 1C.

Fig. 10 is a view showing stationary vanes provided with tapered surfaces and with vertical surfaces and circumferential surfaces on the inner rim and the outer rim in embodiment 1D.

Fig. 11 is a view showing a stationary vane in which tapered surfaces are provided on the inner rim and the outer rim in embodiment 1E, and the tapered surfaces are also present on the upper side (lower side) of the outer rim with respect to the vanes.

Fig. 12 is a view showing a stationary vane in which tapered surfaces are provided on an inner rim and an outer rim of embodiment 1F, and an inner circumferential surface is present above (below) a vane.

Fig. 13 is a view showing a stationary vane provided with a tapered surface on the inner rim and the outer rim, and a vertical surface having an inner peripheral surface on the upper side (lower side) of the outer rim with respect to the vane in embodiment 1G.

Fig. 14 is a view showing a stationary vane provided with a tapered surface on the inner rim and the outer rim of embodiment 1H, a tapered surface on the upper side (lower side) of the outer rim with respect to the vane, and a vertical surface.

Fig. 15 is a view showing a stationary vane provided with a flange and tapered surfaces at an inner rim and an outer rim in embodiment 1I.

Fig. 16 is a view showing a stationary vane provided with a flange and a vertical surface, in which tapered surfaces are provided on an inner rim and an outer rim in embodiment 1J.

Fig. 17 is a partially enlarged view showing a schematic configuration example of a turbomolecular pump according to embodiment 2 of the present invention.

Fig. 18 is a view showing a stationary vane provided with a tapered surface and an inner peripheral surface at an outer rim in embodiment 2 a.

Fig. 19 is a view showing a stationary vane provided with a flange and a tapered surface and an inner peripheral surface at an outer rim in embodiment 2B.

Fig. 20 is a view showing a stationary vane provided with a tapered surface and an inner peripheral surface at an outer rim and provided with an inner rim vertical surface and an outer rim vertical surface in embodiment 2C.

Fig. 21 is a view showing a fixed vane provided with a flange and a tapered surface and an inner peripheral surface at an outer rim in embodiment 2D.

Fig. 22 is a partially enlarged view of the turbomolecular pump according to embodiment 3.

Fig. 23 is a partially enlarged view of the turbomolecular pump according to embodiment 4.

Fig. 24 is a view showing a stationary vane in which an inner rim tapered surface is provided at an inner rim according to embodiment 4 a.

Fig. 25 is a view showing a stationary vane in which an inner bead tapered surface is provided on an inner bead and an inner bead vertical surface is provided in embodiment 4B.

Fig. 26 is a partially enlarged view of the turbomolecular pump according to embodiment 5.

Fig. 27 is a view showing an external appearance of a fixed-wing spacer according to embodiment 5 a.

Fig. 28 is a view showing an appearance of the fixed-wing spacer according to embodiment 5B.

Fig. 29 is a diagram for explaining the angle of the taper.

Fig. 30 is a view showing a conventional stationary blade.

Fig. 31 is a partially enlarged view of the stationary blade shown in fig. 30.

Fig. 32 is a view showing a conventional stationary vane of the type having no outer rim.

Fig. 33 is a partially enlarged view of the stationary blade shown in fig. 32.

Fig. 34 is a diagram showing a schematic configuration example of a conventional turbomolecular pump.

Fig. 35 is a partially enlarged view of the turbomolecular pump shown in fig. 34.

Detailed Description

(i) Brief description of the embodiments

In the present embodiment, in the vacuum pump in which the outer diameter of at least one of the plurality of layers of rotary blades is formed so that the outer diameter on the exhaust port side becomes small or the inner diameter of at least one of the plurality of layers of rotary blades is formed so that the inner diameter on the exhaust port side becomes large, a tapered surface (inclined surface) is provided on at least one of the outer peripheral portion or the inner peripheral portion of the stationary blade disposed immediately after the rotary blade having the small outer diameter or the rotary blade having the large inner diameter, and the tapered surface (inclined surface) has a descending gradient toward the exhaust port side.

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

Thus, the outer peripheral portion or the inner peripheral portion of the stationary blade, which does not act on the exhaust gas in the conventional technique, contributes to the exhaust gas, and the exhaust efficiency of the vacuum pump is improved.

(ii) Detailed description of the embodiments

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to fig. 1 to 29.

(Structure of vacuum pump)

Fig. 1 is a diagram showing a schematic configuration example of a turbomolecular pump 100 according to an embodiment of the present invention, and the turbomolecular pump 100 has an inlet port 101 formed at an upper end of a cylindrical outer cylinder 127. A rotor 103 is provided inside the outer tube 127, and the rotor 103 forms a plurality of rotor blades 102 (102 a, 102b, 102 c) for sucking and discharging gas, that is, a plurality of rotor blades 102, radially in a plurality of layers on the periphery. A rotor shaft 113 is attached to the center of the rotating body 103, and the rotor shaft 113 is supported in an air-bearing state by, for example, a 5-axis controlled magnetic bearing and is position-controlled.

The upper radial electromagnets 104 are 4 electromagnets arranged in pairs on the X axis and the Y axis. In the vicinity of the upper radial electromagnets 104, 4 upper radial sensors 107 are provided corresponding to the upper radial electromagnets 104. The upper radial sensor 107 detects the position of the rotor shaft 113 based on a change in inductance of a conductive winding that changes in accordance with the position of the rotor shaft 113, using, for example, an inductance sensor or an eddy current sensor having the conductive winding. The upper radial sensor 107 is configured to detect the rotor shaft 113, that is, radial displacement of the rotating body 103 fixed to the rotor shaft 113, and send the displacement to the control device 200.

In the control device 200, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on a position signal detected by the upper radial sensor 107, and an amplification circuit 150 (described later) shown in fig. 2 performs excitation control for the upper radial electromagnet 104 based on the excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

The rotor shaft 113 is made of a high-permeability material (iron, stainless steel, or the like) and is attracted by the magnetic force of the upper radial electromagnet 104. The adjustment is performed independently in the X-axis direction and the Y-axis direction, respectively. The lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107, and the radial position of the rotor shaft 113 on the lower side is adjusted in the same manner as the radial position on the upper side.

Further, the

axial electromagnets

106A and 106B are disposed so as to sandwich a disk-shaped metal plate 111 provided below the rotor shaft 113 from above and below. The metal plate 111 is made of a high magnetic permeability material such as iron. The axial sensor 109 is provided to detect the axial displacement of the rotor shaft 113, and the axial position signal is transmitted to the control device 200.

In the control device 200, for example, a compensation circuit 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 based on these excitation control command signals, whereby the axial electromagnet 106A attracts the metal plate 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal plate 111 downward, thereby adjusting the axial position of the rotor shaft 113.

In this way, the control device 200 appropriately adjusts the magnetic force that acts on the metal disk 111 by the

axial electromagnets

106A and 106B, and magnetically suspends the rotor shaft 113 in the axial direction, thereby maintaining the rotor shaft in a spatially non-contact manner. The amplification circuit 150 for controlling the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the

axial electromagnets

106A and 106B will be described later.

On the other hand, the motor 121 includes a plurality of magnetic poles circumferentially arranged so as to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 so that the rotor shaft 113 is rotationally driven via electromagnetic force acting between the rotor shaft 113 and the magnetic pole. Further, a rotation speed sensor, not shown in the figure, such as a hall element, an analyzer, an encoder, or the like, is incorporated in the motor 121, and the rotation speed of the rotor shaft 113 is detected by a detection signal of the rotation speed sensor.

Further, for example, a phase sensor, not shown, is attached near the lower radial sensor 108 to detect the phase of rotation of the rotor shaft 113. The control device 200 detects the position of the magnetic pole by using the detection signals of the phase sensor and the rotation speed sensor.

A plurality of stationary blades 123 (123 a, 123b, 123 c) are provided with a slight gap from the rotary blades 102 (102 a, 102b, 102 c). The rotary blades 102 (102 a, 102b, 102c · · are formed to be inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transfer molecules of the exhaust gas downward by collision, respectively.

Similarly, the stationary blades 123 are inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are alternately disposed inside the outer tube 127 and on the layers of the rotary blades 102. And the number of the first and second electrodes, the outer peripheral end of the stationary blade 123 is supported in a state of being inserted between the plurality of stacked stationary blade spacers 125 (125 a, 125b, 125 c).

The stationary blade spacer 125 is an annular member made of a metal such as aluminum, iron, stainless steel, or copper, or a metal such as an alloy containing these metals as a component. An outer cylinder 127 is fixed to the outer periphery of the fixed-wing spacer 125 with a slight gap. A base portion 129 is disposed at the bottom of the outer cylinder 127. The base portion 129 is provided with an exhaust port 133 communicating with the outside. The exhaust gas entering the inlet port 101 from the cavity side and transferred to the base portion 129 is sent to the exhaust port 133.

Further, a threaded spacer 131 is disposed between the lower portion of the stationary vane spacer 125 and the base portion 129 for the purpose of the turbomolecular pump 100. The threaded spacer 131 is a cylindrical member made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals as components, and has a plurality of spiral thread grooves 131a engraved on the inner circumferential surface thereof. The spiral direction of the screw groove 131a is a direction in which the molecules of the exhaust gas are transferred to the exhaust port 133 when the molecules move in the rotation direction of the rotating body 103. The cylindrical portion 102d hangs down at the lowermost portion continuous with the rotor blades 102 (102 a, 102b, 102c · · of the rotor 103. The cylindrical portion 102d has a cylindrical outer peripheral surface, extends toward the inner peripheral surface of the threaded spacer 131, and is close to the inner peripheral surface of the threaded spacer 131 with a predetermined gap. The exhaust gas transferred to the screw groove 131a by the rotary blades 102 and the stationary blades 123 is guided by the screw groove 131a and sent to the base portion 129.

The base 129 is a disk-shaped member constituting a base portion of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, or stainless steel. The base portion 129 physically holds the turbo-molecular pump 100 and also functions as a heat conduction path, and therefore, it is desirable to use a metal having rigidity and high thermal conductivity, such as iron, aluminum, or copper.

In this configuration, when the rotary blades 102 are rotationally driven by the motor 121 together with the rotor shaft 113, the discharged gas is sucked from the chamber through the suction port 101 by the action of the rotary blades 102 and the stationary blades 123. The exhaust gas sucked from the suction port 101 passes between the rotary blades 102 and the stationary blades 123, and is transferred to the base portion 129. At this time, the temperature of the rotary blades 102 rises due to frictional heat generated when the exhaust gas contacts the rotary blades 102, conduction of heat generated by the motor 121, or the like, but the heat is transmitted to the stationary blades 123 side by radiation, conduction of gas molecules of the exhaust gas, or the like.

The fixed vane spacers 125 are joined to each other at the outer peripheral portions thereof, and transmit heat received by the fixed vanes 123 from the rotary vanes 102, frictional heat generated when the exhaust gas contacts the fixed vanes 123, and the like to the outside.

In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotating body 103, and the threaded groove 131a is formed on the inner peripheral surface of the threaded spacer 131. However, on the contrary, a thread groove may be cut in the outer peripheral surface of the cylindrical portion 102d, and a spacer having a cylindrical inner peripheral surface may be disposed around the thread groove.

Further, depending on the use of the turbomolecular pump 100, there are also the following cases: the electric part is covered with the stator pole 122 so that the gas sucked from the inlet port 101 does not enter the electric part including the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the

axial electromagnets

106A and 106B, the axial sensor 109, and the like, and the stator pole 122 is held at a predetermined pressure by the purge gas.

In this case, a pipe not shown is disposed at the base portion 129, and the purge gas is introduced through the pipe. The introduced purge gas passes through the gap between the protection bearing 120 and the rotor shaft 113, the gap between the rotor and the stator of the motor 121, and the gap between the stator post 122 and the inner circumferential cylindrical portion of the rotary vane 102, and is discharged to the exhaust port 133.

Here, the turbomolecular pump 100 needs to be controlled based on the model determination and the parameters (for example, characteristics corresponding to the model) inherent to the individual adjustment. In order to store the control parameters, the turbo-molecular pump 100 includes an electronic circuit unit 141 in its main body. The electronic circuit section 141 is constituted by a semiconductor memory such as an EEP-ROM, an electronic component such as a semiconductor element used for access thereof, a substrate 143 for mounting them, and the like. The electronic circuit section 141 is housed in a lower portion of a rotation speed sensor, not shown, for example, in the vicinity of the center of the base section 129, and is closed by an airtight bottom cover 145, and the base section 129 constitutes a lower portion of the turbomolecular pump 100.

However, in a semiconductor manufacturing process, a process gas introduced into a chamber includes a substance having a property of becoming a solid when a pressure thereof becomes higher than a predetermined value or a temperature thereof becomes lower than a predetermined value. Inside the turbo-molecular pump 100, the pressure of the exhaust gas is lowest at the inlet port 101 and highest at the outlet port 133. When the pressure of the process gas is higher than a predetermined value and the temperature thereof is lower than a predetermined value while the process gas is transferred from the inlet 101 to the outlet 133, the process gas is in a solid state and adheres to and accumulates inside the turbomolecular pump 100.

For example, siCl is used for Al etching apparatus ₄ In the case of the process gas, the low vacuum (760 [ torr ]) is known from the vapor pressure curve]～10 ^-2 Torr) and low temperature (about 20[ °C)]) When solid products (e.g. AlCl) ₃ ) Precipitates and deposits inside the turbomolecular pump 100. As a result, when the precipitates of the process gas are deposited inside the turbomolecular pump 100, the deposits narrow the pump flow path, which causes a decrease in the performance of the turbomolecular pump 100. The product is in a state of being easily solidified and adhered at a portion near the exhaust port and near the threaded spacer 131 where the pressure is high.

Therefore, in order to solve this problem, conventionally, a heater (not shown) or an annular water cooling tube 149 is wound around the outer periphery of the base portion 129 and the like, and a Temperature sensor (not shown) (for example, a thermistor) is embedded in the base portion 129, and the heater and the water cooling tube 149 are controlled to be heated (hereinafter, referred to as tms.tms; temperature Management System) so that the Temperature of the base portion 129 is kept at a constant high Temperature (set Temperature) based on a signal of the Temperature sensor.

Next, with respect to the turbomolecular pump 100 configured as described above, the amplification circuit 150 that performs excitation control of the upper radial electromagnet 104, the lower radial electromagnet 105, and the

axial electromagnets

106A and 106B will be described. Fig. 2 shows a circuit diagram of the amplifying circuit 150.

In fig. 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 and the like is connected to the positive electrode 171a of the power source 171 via the transistor 161, and the other end is connected to the negative electrode 17lb of the power source 171 via the current detection circuit 181 and the transistor 162. The transistors 161 and 162 are so-called power field effect transistors, and have a structure in which a diode is connected to a source and a drain thereof.

In this case, the transistor 161 has a diode with a cathode terminal 161a connected to the anode 171a and an anode terminal 161b connected to one end of the electromagnet winding 151. In addition, the transistor 162 has a diode with a cathode terminal 162a connected to the current detection circuit 181 and an anode terminal 162b connected to the cathode 171 b.

On the other hand, the diode 165 for current regeneration has a cathode terminal 165a connected to one end of the electromagnet winding 151 and an anode terminal 165b connected to the negative electrode 171 b. Similarly, the current regeneration diode 166 has a cathode terminal 166a connected to the positive electrode 171a, and an anode terminal 166b connected to the other end of the electromagnet winding 151 via the current detection circuit 181. The current detection circuit 181 is constituted by, for example, a hall sensor type current sensor or a resistance element.

The amplification circuit 150 configured as described above corresponds to one electromagnet. Therefore, when the magnetic bearing is controlled by 5 axes and the total number of

electromagnets

104, 105, 106A, and 106B is 10, the same amplification circuit 150 is configured for each electromagnet, and 10 amplification circuits 150 are connected in parallel to the power source 171.

Further, 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 the amplification control circuit 191 switches on/off of the transistors 161 and 162.

The amplification control circuit 191 compares the current value detected by the current detection circuit 181 (a signal reflecting the current value is referred to as a current detection signal 191 c) with a predetermined current command value. Then, based on the comparison result, the magnitude of the pulse width (pulse width time Tp1, tp 2) generated in the control period Ts, which is one period of the PWM control, is determined. As a result, the gate drive signals 191a and 191b having the pulse width are output from the amplification control circuit 191 to the gate terminals of the transistors 161 and 162.

Further, when the rotational speed of the rotating body 103 passes a resonance point during the acceleration operation, when external disturbance occurs during the constant speed operation, or the like, it is necessary to perform high-speed and strong position control of the rotating body 103. Therefore, in order to enable a rapid increase (or decrease) in the current flowing through the electromagnet winding 151, a high voltage of, for example, about 50V is used as the power source 171. In order to stabilize the power source 171, a capacitor is usually connected between the positive electrode 171a and the negative electrode 171b of the power source 171 (not shown).

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.

When one of the transistors 161 and 162 is turned on and the other is turned off, a so-called freewheel current is held. In this way, the flywheel current flows through the amplifier circuit 150, so that the hysteresis loss of the amplifier circuit 150 is reduced, and the power consumption of the entire circuit can be reduced. By controlling the transistors 161 and 162 in this manner, high-frequency noise such as a harmonic wave generated in the turbo molecular pump 100 can be reduced. Further, by measuring the flywheel current through the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.

That is, when the detected current value is smaller than the current command value, both the transistors 161 and 162 are turned on 1 time corresponding to the pulse width time Tp1 in the control period Ts (for example, 100 μ s) as shown in fig. 3. Therefore, the electromagnet current iL during this period increases from the positive electrode 171a toward the negative electrode 171b to a current value iLmax (not shown) that can flow through the transistors 161 and 162.

On the other hand, when the detected current value is larger than the current command value, both of the transistors 161 and 162 are cut 1 time in the control period Ts for a time corresponding to the pulse width time Tp2, as shown in fig. 4. Therefore, the electromagnet current iL during this period decreases from the negative electrode 171b toward the positive electrode 171a to a current value iLmin (not shown) that can be regenerated via the

diodes

165 and 166.

In either case, after the pulse width time Tp1 or Tp2 elapses, either of the transistors 161 and 162 is turned on. Therefore, during this period, the flywheel current is held at the amplification circuit 150.

(embodiment 1)

Next, embodiment 1 will be described with reference to fig. 5 to 16.

Fig. 5 is a diagram showing a schematic configuration example of the turbomolecular pump according to embodiment 1, and fig. 6 is a partially enlarged view of the turbomolecular pump according to embodiment 1 shown in fig. 5.

In embodiment 1, the inner rim 600, the outer rim 700, or both of the fixed vanes 123 are provided with tapered surfaces (inner rim tapered surface 610 and outer rim tapered surface 710) having a descending slope toward the exhaust port side.

The portion where the tapered surface is provided is a portion where the outer diameter of one of the plurality of layers of rotary blades is formed such that the outer diameter of the exhaust port side is small, or a portion where the inner diameter of one of the plurality of layers of rotary blades is formed such that the inner diameter of the exhaust port side is large. A stationary blade 123 having a tapered surface is disposed between these rotary blades.

Fig. 7 is a view showing a stationary vane 123 having a tapered surface provided on an inner rim according to embodiment 1a.

As shown in this figure, inner bead cone surface 610 is provided on inner bead 600, and inner bead cone surface 610 has a decreasing slope toward the exhaust side. When the molecules collide with the inner rim cone 610, they are reflected at right angles, collide with the upper rotating wing, and are sent to the next layer. From this perspective, inner rim cone surface 610 is also provided at inner rim 600, thereby contributing to the venting action. As can be seen from this figure, the vanes 550 of the fixed vane 123 are held and fixed by the inner rim 600 and the outer rim 700.

Fig. 8 is a view showing a stationary vane 123 having a tapered surface provided on an inner rim according to embodiment 1B. The stationary vane 123 of embodiment 1B defines an inner bead vertical surface 620 and an inner bead circumferential surface 630.

The stationary blade 123 is made of, for example, aluminum, and is manufactured as a cast product by a die or by cutting.

When the mold is used to produce a cast product, the product must be removed from the mold, and therefore the inner bead vertical surface 620 is provided. An inner bead circumferential surface 630 parallel to the outer bead 700 is formed on the lower side of the vane 550 at a location where the inner bead vertical surface 620 is formed.

Fig. 9 is a view showing the fixing vanes 123 having tapered surfaces provided on the inner rim and the outer rim in embodiment 1C. As shown in this figure, outer rim cone surface 710 is provided not only on inner rim 600 but also on outer rim 700, and outer rim cone surface 710 has a downward slope toward the exhaust port.

In embodiment 1C, not only the inner rim 600, but also the outer rim 700 contributes to the venting action.

In embodiment 1C, tapered surfaces (610, 710) are provided on both sides of inner rim 600 and outer rim 700, but outer rim tapered surface 710 may be provided only on outer rim 700.

Fig. 10 is a view showing the stationary vane 123 having tapered surfaces and vertical and circumferential surfaces provided on the inner rim and the outer rim in embodiment 1D.

In the same manner as embodiment B1, when the product is manufactured as a cast product by a mold, the product needs to be extracted from the mold, and therefore, the outer rim vertical surface 720 is provided. An outer bead circumferential surface 730 parallel to the inner bead 600 is formed on the lower side of the vane 550 at a location where the outer bead vertical surface 720 is formed.

Fig. 11 (a) and (b) show stationary vanes 123 having tapered surfaces on the inner and outer rims of embodiment 1E, and having tapered surfaces also on the upper side (lower side) of the outer rim with respect to the vanes.

The inner rim 600 side of embodiment 1E has the same shape as embodiments 1a and C, but the outer rim 700 has a different structure from embodiment 1C. That is, in the embodiment shown in fig. 11 (a), the outer rim tapered surface 710 is formed to a position above the surface of the vane 550, and the remaining portion 740 is present.

On the other hand, in the embodiment shown in fig. 11 (b), the outer rim tapered surface 710 is formed to a position lower than the back surface of the vane 550, and an excess portion 740 is present.

Due to the presence of the excess portion 740, it becomes easy to define the axial dimension of the stationary blade 123. That is, the height direction can be adjusted within a range in which the blade 550 does not affect.

In embodiment 1E, the tapered surfaces (610, 710) are provided on both sides of the inner rim 600 and the outer rim 700, but the outer rim tapered surface 710 may be provided only on the outer rim 700.

In embodiment 1E, since there is no vertical surface, it is manufactured by cutting.

Fig. 12 is a view showing a stationary vane 123 in which tapered surfaces are provided on the inner rim and the outer rim of embodiment 1F, and an inner circumferential surface is present above (below) the vane.

The inner rim 600 side of embodiment 1F has the same shape as embodiments 1a and C, but the outer rim 700 has a different structure from embodiment 1C. That is, the outer rim inner peripheral surface 760 is formed above (below) the surface of the vane 550. The outer rim inner peripheral surface 760 is a surface parallel to the axial direction of the turbomolecular pump 100, unlike the outer rim tapered surface 710.

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

In embodiment 1F, tapered surfaces (610, 710) are provided on both sides of inner rim 600 and outer rim 700, but tapered surface 710 may be provided only on outer rim 700.

In embodiment 1F, since there is no vertical surface, it is manufactured by cutting.

Fig. 13 is a view showing a stationary vane 123 in which tapered surfaces are provided on the inner rim and the outer rim of embodiment 1G, and a vertical surface is provided with an inner peripheral surface at a position above (below) the vane on the outer rim. This embodiment G differs from embodiment F1 in that an inner bead vertical plane 620 and an outer bead vertical plane 720 are provided.

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

In embodiment 1G, tapered surfaces (610, 710) are provided on both sides of inner rim 600 and outer rim 700, but outer rim tapered surface 710 may be provided only on outer rim 700.

Fig. 14 (a) and (b) show a stationary vane 123 having tapered surfaces on the inner rim and the outer rim, and having a vertical surface in which the tapered surfaces are present at positions on the outer rim above (below) the vanes, in embodiment 1H. (a) Is an external view from the upper side, and (b) is an external view from the lower side.

This embodiment differs from embodiment E of embodiment 1 in that an inner bead vertical plane 620 and an outer bead vertical plane 720 are provided.

Due to the existence of the surplus portion 740, it becomes easy to define the axial dimension of the stationary blade 123.

In embodiment 1H, tapered surfaces (610, 710) are provided on both sides of inner rim 600 and outer rim 700, but tapered surface 710 may be provided only on outer rim 700.

Fig. 15 is a view showing a fixing vane 123 having a flange and tapered surfaces provided on the inner rim and the outer rim in embodiment 1I.

In embodiment I, a flange 750 protruding outward (toward the outer cylinder 127 when installed) from the outer rim 700 is provided.

The flange 750 enables positioning and holding of the stationary blade 123 in the axial direction. That is, the thickness (height in the axial direction) of the flange 750 is adjusted to position the stationary blade 123 in the axial direction, and the flange 750 is sandwiched to fix the stationary blade to the outer cylinder 127.

In embodiment 1I, tapered surfaces (610, 710) are provided on both sides of inner rim 600 and outer rim 700, but outer rim tapered surface 710 may be provided only on outer rim 700.

In embodiment 1I, since there is no vertical surface, it is manufactured by cutting.

Fig. 16 shows a fixing wing 123 having a flange, in which tapered surfaces are provided on the inner rim and the outer rim in embodiment 1J, and an inner rim vertical surface and an outer rim vertical surface are provided.

In embodiment J, as in embodiment I, a flange 750 projecting outward (toward the outer cylinder 127 when installed) from the outer rim 700 is provided.

Embodiment J differs from embodiment 1I in that an inner bead vertical face 620 and an outer bead vertical face 720 are provided.

In embodiment 1J, tapered surfaces (610, 710) are provided on both sides of inner rim 600 and outer rim 700, but outer rim tapered surface 710 may be provided only on outer rim 700.

(embodiment 2)

Next, embodiment 2 will be described with reference to fig. 17 to 21.

Fig. 17 is a partially enlarged view of the turbomolecular pump according to embodiment 2.

In embodiment 2, an outer rim cone surface 710 having a downward inclination toward the exhaust port side and an outer rim inner peripheral surface 760 are provided on an outer rim 700 of a fixed vane 123. That is, it is characterized by the coexistence of outer rim cone 710 and outer rim inner periphery 760 at outer rim 700. The inner rim 600 is similar to that of embodiment 1.

Fig. 18 is a view showing a stationary vane 123 having a tapered surface and an inner peripheral surface at an outer rim according to embodiment 2 a.

The outer rim cone surface 710 is disposed at a position corresponding to the vane 550. At its lower portion, an outer rim inner peripheral surface 760 is provided. The outer rim inner peripheral surface 760 is not inclined and is parallel to the axial direction of the turbomolecular pump 100.

By adjusting the height direction of the outer rim inner peripheral surface 760, the fixed vane 123 can be positioned. The vanes 550 are not present at positions corresponding to the outer rim inner peripheral surface 760, and therefore adjustment can be easily performed.

In embodiment 2a, tapered surfaces (610, 710) are provided on both the inner rim 600 and the outer rim 700, but the outer rim tapered surface 710 may be provided only on the outer rim 700.

In embodiment 2a, since there is no vertical surface, it is manufactured by cutting.

Fig. 19 shows a stationary vane 123 having a flange and a tapered surface and an inner peripheral surface provided on an outer rim in embodiment 2B.

The outer rim cone surface 710 is disposed at a position corresponding to the vane 550. At its lower portion, an outer rim inner peripheral surface 760 is provided.

Embodiment 2B differs from embodiment 2a in that a flange 750 projecting outward of the outer rim 700 (toward the outer tube 127 when installed) is provided.

In embodiment 2B, tapered surfaces (610, 710) are provided on both the inner rim 600 and the outer rim 700, but the outer rim tapered surface 710 may be provided only on the outer rim 700.

In embodiment 2B, since there is no vertical surface, it is manufactured by cutting.

Fig. 20 shows a fixing wing 123 having a tapered surface and an inner peripheral surface at the outer rim and having an inner rim vertical surface and an outer rim vertical surface in embodiment 2C.

Embodiment C differs from embodiment 2a in that, when the product is manufactured as a cast product by means of a mold, the product needs to be pulled out of the mold, and therefore the inner bead vertical surface 630 and the outer bead vertical surface 720 are provided.

In embodiment 2C, tapered surfaces (610, 710) are provided on both the inner rim 600 and the outer rim 700, but the outer rim tapered surface 710 may be provided only on the outer rim 700.

Fig. 21 shows a stationary vane 123 having a flange and a tapered surface and an inner peripheral surface provided on an outer rim in embodiment 2D.

Embodiment 2D differs from embodiment 2C in that a flange 750 projecting outward of the outer rim 700 (toward the outer tube 127 when installed) is provided.

In embodiment 2D, the tapered surfaces (610, 710) are provided on both sides of the inner rim 600 and the outer rim 700, but the outer rim tapered surface 710 may be provided only on the outer rim 700.

(embodiment 3)

Next, embodiment 3 will be described with reference to fig. 22.

In embodiment 3, the fixed blades 123 used in embodiment 1 are arranged in the opposite direction or the same direction. At least the fixed wing 123 of the final layer is reversely disposed.

By disposing the fixed wing 123 in this way, the product (fixed wing 123) of the same size can be used as well, and the manufacturing cost can be reduced.

Further, since the outer rim tapered surface 710 is continuously continuous, a gap with respect to the spacer can be eliminated.

(embodiment 4)

Next, embodiment 4 will be described with reference to fig. 23 to 25.

Fig. 23 is a partially enlarged view of the turbomolecular pump of embodiment 4.

In embodiment 4, the inner rim 600 of the stationary vane 123 is provided with an inner rim tapered surface 610 having a downward slope toward the exhaust port side. That is, the inner rim 600 is provided with the inner rim taper surface 610, and the inner rim 600 is located at a portion where the root diameter of the vane 550 of the upstream stationary vane 123 is smaller than the root diameter of the vane 550 of the downstream stationary vane 123.

Figure 24 shows stationary vane 123 with inner bead cone 610 on inner bead 600 of embodiment 4 a. The inner rim 600 shown in figure 24 is manufactured by cutting because it does not have an inner rim vertical face 620.

Fig. 25 shows stationary vane 123 having inner bead cone surface 610 and inner bead vertical surface at inner bead 600 in embodiment 4B. The inner rim 600 shown in figure 25 is manufactured as a cast part with the help of a mold due to the presence of the inner rim vertical surface 620.

Both fig. 24 and 25 show the type of fixed wing 123 without the outer rim 70, but embodiment 4 can also be applied to the type of fixed wing 123 with the outer rim 700.

(embodiment 5)

Next, embodiment 5 will be described with reference to fig. 26 to 28.

The embodiment 5 relates to a fixed-wing spacer 800, and the fixed-wing spacer 800 includes a fixed-wing spacer section 870 for positioning the fixed wing 123 in the height direction while holding the frame 127 side.

Fig. 27 (embodiment 5 a) and 28 (embodiment 5B) are views showing an external appearance of the fixed-wing spacer 800. As shown in these figures, the stationary vane spacer 800 is provided with a projecting portion 860, the projecting portion 860 projects in the height direction in the range of the height direction projecting from the spacer portion 870 to the stationary vane 123, and a stationary vane spacer tapered surface 810 having a downward slope toward the exhaust port side is formed on at least a part of the inner peripheral surface 830 of the stationary vane spacer portion 870 and the projecting portion 860. The range in which the inner peripheral surface 830 and the protruding portion 860 of the stationary vane spacer portion 870 protrude into the range in the height direction of the stationary vane 123 is also defined as "the outer peripheral portion of the stationary vane".

Between the projections 860, there are provided blade fitting grooves 820 for fitting and holding the blades 550 of the fixed blades 123 at the time of installation.

The fixed-wing spacer 800 shown in fig. 28 is also provided with a fixed-wing spacer flange 850. The stationary-blade spacer 800 can be held and fixed by positioning or clamping the stationary-blade spacer 800 in the height direction via the stationary-blade spacer flange 850.

(Angle of taper)

The angle of the tapered surface in each of embodiments 1 to 5 is explained.

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

Fig. 29 (a) is a sectional view of the stationary blade 123 corresponding to embodiment 1H. In the example shown in the drawing, the fixed vane 123 is provided with a tapered surface at an angle of a line (imaginary line) connecting the inner diameter lower end a of the fixed vane spacer 125 and the inner diameter upper end B of the fixed vane spacer 125.

Fig. 29 (b) is a sectional view of the stationary blade 123 according to embodiment 2D. In the example shown in the figure, the tapered surface is provided at the fixed blade 123 at an angle of a line (virtual line) connecting an intersection point H of perpendicular lines hanging from the tip X of the upper rotary blade 102 to the lower fixed blade 123 and (1) (the root of the blade 550 of the fixed blade 123) or (2) (the inner peripheral lower surface of the fixed blade 123).

Thus, the angle of the tapered surface can be set to various angles, and can be appropriately determined according to various conditions.

In each embodiment, not only the tapered surface but also a gently curved surface may be used.

The embodiment and the modifications of the present invention may be combined as necessary.

In addition, the present invention can be variously modified as long as it does not depart from the spirit of the present invention, and it is apparent that the present invention also relates to the modification.

Description of the reference numerals

100. Turbo molecular pump

101. Air suction inlet

102. Rotary wing

103. Rotating body

113. Rotor shaft

123. Fixed wing

125. Fixed wing spacer

127. Outer cylinder

129. Base part

133. Exhaust port

200. Control device

550. Blade

600. Inner rim ring

610. Conical surface of inner rim ring

620. Vertical plane of inner rim ring

630. Circumferential surface of inner rim

700. Outer rim ring

710. Conical surface of outer rim ring

720. Vertical plane of outer rim ring

730. Outer rim ring circumferential surface

740. The remainder being

750. Flange

760. Inner peripheral surface of outer rim

800. Fixed wing spacer

810. Conical surface of fixed wing spacer

820. Blade fitting groove

830. Inner peripheral surface of fixed wing spacer

850. Fixed wing spacer flange

860. Projection part

870. A fixed wing spacer portion.

Claims

1. A vacuum pump comprising a housing, a rotary shaft, a plurality of rotary vanes, a plurality of stationary vanes,

the housing has an air intake port and an air exhaust port,

the rotating shaft is rotatably supported in the housing,

the multi-layer rotary wing is fixed on the rotating shaft and can rotate together with the rotating shaft,

the multi-layer fixed wing is fixed relative to the shell and arranged between the rotating wings,

at least one of the plurality of layers of rotary blades has an outer diameter smaller than that of the suction port side, or has an inner diameter larger than that of the suction port side,

the aforementioned vacuum pump is characterized in that,

a tapered surface having a descending slope toward the exhaust port side is provided on an outer peripheral portion or an inner peripheral portion of a stationary blade disposed above the rotary blade having a small outer diameter or a large inner diameter.

2. Vacuum pump according to claim 1,

the fixed wing has a plurality of radially arranged blades, an inner rim ring or an outer rim ring for holding the plurality of blades,

a tapered surface is provided on the outer peripheral surface of the inner rim or the inner peripheral surface of the outer rim, and the tapered surface has a descending slope toward the exhaust port.

3. Vacuum pump according to claim 1,

the stationary blade has a plurality of blades radially arranged, a spacer portion holding the plurality of blades and positioning the stationary blade in a height direction,

the inner peripheral surface of the spacer portion is provided with a tapered surface having a descending slope toward the exhaust port side.

4. A vacuum pump according to claim 2 or 3,

undercut to the surface of the exhaust port side of the plurality of blades of the stationary blade.

5. A vacuum pump according to claim 2 or 3,

a vertical surface or a tapered surface is provided behind the plurality of blades of the stationary blade.

6. Vacuum pump according to claim 1,

a protruding part protruding from a spacer part to a height direction range of the fixed wing, the spacer part holding the shell side of the fixed wing and positioning the fixed wing in the height direction,

the inner peripheral surface of the spacer portion and at least a part of the protruding portion are provided with tapered surfaces having a descending slope toward the exhaust port side.

7. A stationary vane for a vacuum pump, the vacuum pump including a housing having an air inlet and an air outlet,

comprises a plurality of radially arranged vanes, an inner rim or an outer rim for holding the vanes,

a tapered surface is provided on the outer peripheral surface of the inner rim or the inner peripheral surface of the outer rim, and the tapered surface has a downward slope toward the exhaust port.

8. A spacer for a vacuum pump, the vacuum pump including a housing having an intake port and an exhaust port,

having a spacer part for holding the shell side and positioning the stationary blade in the height direction when the stationary blade is disposed, the stationary blade having a plurality of blades radially disposed,

a protruding part protruding from the spacer part to the height direction of the fixed wing,

the inner peripheral surface of the spacer portion and at least a part of the protruding portion are provided with tapered surfaces having a downward slope toward the exhaust port side.