Vacuum pump

Abstract

Provided is a vacuum pump capable of stably controlling the temperature of a gas without compromising the cooling effect of the gas. A vacuum pump (100) is provided with: a casing (126, 127); a rotor shaft (113) rotatably supported inside the housing; a plurality of stages of rotating blades (102) fixed to the rotor shaft and capable of rotating together with the rotor shaft; a plurality of stages of fixed blades (123) fixed to the casing and disposed between the plurality of stages of rotating blades; and a plurality of stages of fixed blade spacers (125) that support the plurality of stages of fixed blades. The vacuum pump (100) is provided with: a temperature adjustment mechanism (110) that is provided to a specific spacer (128, 228) of one of a plurality of stages of fixed blade spacers, and that adjusts the temperature of the specific spacer; and a temperature sensor (185) provided at a position closer to the temperature adjustment mechanism than a gas flow path (F1) of a turbine pump unit comprising the multiple stages of rotating blades and the multiple stages of fixed blades.

Description

Technical Field

[0001] The present invention relates to a vacuum pump. Background Art

[0002] As a prior art in this technical field, for example, the turbo molecular pump described in Patent Document 1 includes a temperature adjustment unit provided between a casing and a base. This temperature adjustment unit is configured to include a temperature adjustment spacer that forms a pump casing together with the casing and the base, and a cooling water pipe, a heater, and a temperature detection unit provided in the temperature adjustment spacer. Moreover, according to Patent Document 1, the temperature controllability of the stator blades on the downstream side of the turbo pump unit is improved.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2022-073913 Summary of the Invention

[0006] Technical Problem to be Solved by the Invention

[0007] However, in the temperature adjustment unit of Patent Document 1, since the cooling water pipe is located relatively close to the gas flow path, the temperature of the gas is easily affected by the temperature of the cooling water pipe, and there is a technical problem that the control of the gas temperature is unstable.

[0008] Therefore, an object of the present invention is to provide a vacuum pump capable of stably controlling the temperature of a gas without impairing the cooling effect of the gas.

[0009] Means for Solving the Technical Problem

[0010] To achieve the above object, one technical solution of the present invention is a vacuum pump, comprising: a casing; a rotor shaft rotatably supported inside the casing; a multi-stage rotating blade fixed to the rotor shaft and capable of rotating together with the rotor shaft; a multi-stage fixed blade fixed to the casing and disposed between the multi-stage rotating blades; and a multi-stage fixed blade spacer supporting the multi-stage fixed blades; characterized in that it comprises: a temperature adjustment mechanism provided in a specific spacer of a certain stage among the multi-stage fixed blade spacers to adjust the temperature of the specific spacer; and a temperature sensor provided at a position closer to the temperature adjustment mechanism than the gas flow path of the turbo pump unit constituted by the multi-stage rotating blades and the multi-stage fixed blades.

[0011] In the above structure, it is characterized in that the casing includes an outer cylinder disposed on the outer peripheral side of the rotor shaft and a base portion disposed below the outer cylinder; the specific spacer is made of a component having a higher thermal conductivity than the outer cylinder.

[0012] In the above structure, it is characterized in that the aforementioned specific spacer is made of aluminum material.

[0013] In the above structure, it is characterized in that the aforementioned specific spacer is arranged between the uppermost stage and the lowermost stage of the aforementioned multi-stage stationary blades.

[0014] In the above structure, it is characterized in that the aforementioned specific spacer covers the outer peripheral side of the stationary blade spacers that are axially adjacent.

[0015] In the above structure, it is characterized in that the aforementioned specific spacer includes: a support portion that supports the aforementioned stationary blade spacers that are axially adjacent; and a protruding portion that protrudes outward in the radial direction from the aforementioned support portion to cover the outer peripheral side of the stationary blade spacer; the thickness of the aforementioned protruding portion is larger than the thickness of the aforementioned support portion.

[0016] In the above structure, it is characterized in that the aforementioned temperature sensor is arranged at a position between the aforementioned gas flow path in the radial direction and the aforementioned temperature adjustment mechanism.

[0017] In the above structure, it is characterized in that there is a stationary part arranged on the downstream side of the aforementioned multi-stage rotating blades and the aforementioned multi-stage stationary blades and forming a part of the screw groove pump portion; the aforementioned stationary part is heated by a heating mechanism.

[0018] Advantages of the Invention

[0019] According to the vacuum pump related to the present invention, the temperature of the gas can be stably controlled without impairing the cooling effect of the gas. In addition, other technical problems, structures and effects will become clear from the following description of the embodiments. Brief Description of the Drawings

[0020] Figure 1 It is a longitudinal sectional view of a turbomolecular pump according to the first embodiment of the present invention.

[0021] Figure 2 is Figure 1 The circuit diagram of the amplifier circuit of the turbomolecular pump shown.

[0022] Figure 3 It is a timing chart showing the control of the amplifier control circuit when the current command value is larger than the detected value.

[0023] Figure 4 It is a timing chart showing the control of the amplifier control circuit when the current command value is smaller than the detected value.

[0024] Figure 5 is to Figure 1 The main part enlarged view showing the enlarged A part of.

[0025] Figure 6 is a longitudinal sectional view showing the details of the water-cooled spacer shown in Figure 5 .

[0026] Figure 7 is a longitudinal sectional view of a turbo molecular pump according to a second embodiment of the present invention.

[0027] Figure 8 is a main part enlarged view showing an enlarged view of part B of Figure 7 .

[0028] Figure 9 is a longitudinal sectional view showing the details of the water-cooled spacer shown in Figure 8 . DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, an embodiment of a vacuum pump according to the present invention will be described by taking a turbo molecular pump as an example with reference to the accompanying Figure 1 drawings.

[0030] (First Embodiment)

[0031] In Figure 1 , a longitudinal sectional view of the turbo molecular pump 100 is shown. In Figure 1 , the turbo molecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Further, a rotating body 103 is provided inside the outer cylinder 127, and a plurality of rotating blades 102 (102a, 102b, 102c...) serving as turbo fan blades for sucking and exhausting gas are formed radially and in multiple stages on the circumferential portion of the rotating body 103. A rotor shaft 113 is installed at the center of the rotating body 103, and the rotor shaft 113 is suspended and supported in the air by a magnetic bearing controlled by, for example, a five-axis control and is position-controlled. The rotating body 103 is generally made of a metal such as aluminum, an aluminum alloy, or stainless steel.

[0032] In addition, as shown in Figure 1 , a water-cooled spacer 128 and an outer wall 126 as outer peripheral parts are arranged on the outer peripheral side of the rotating body 103. The water-cooled spacer 128 has a circular cooling pipe 110 (see Figure 5) and the ring-shaped component of the temperature sensor 185. By supplying cooling water to the cooling pipe 110, the parts around the water-cooled spacer 128 are cooled. That is, the heat generated by the rotation of the rotating body 103 is cooled by the water-cooled spacer 128. The outer wall 126 is a cylindrical component that surrounds the substantially lower half of the turbo molecular pump 100. The water-cooled spacer 128 and the outer wall 126 are arranged in sequence below the outer cylinder 127 coaxially with the outer cylinder 127. These outer cylinder 127, water-cooled spacer 128, and outer wall 126 are integrally connected by a plurality of bolts 115 and, together with the base portion 129, constitute the outer packaging body (housing) of the turbo molecular pump 100 that houses the rotating body 103.

[0033] Here, the water-cooled spacer 128 also functions as the fixed blade spacer 125 described later. That is, the water-cooled spacer 128 (specific spacer) constitutes one (one stage) of the plurality of fixed blade spacers 125. In addition, the water-cooled spacer 128 is made of a component with a higher thermal conductivity than the outer cylinder 127 and the outer wall 126, such as aluminum.

[0034] The upper radial electromagnet 104 has four electromagnets arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 107 are provided close to the upper radial electromagnet 104 and corresponding to the upper radial electromagnet 104 respectively. The upper radial sensor 107 uses, for example, an inductance sensor with a conduction coil, an eddy current sensor, etc., and detects the position of the rotor shaft 113 based on the change in the inductance of the conduction coil that changes corresponding to the position of the rotor shaft 113. The upper radial sensor 107 is configured to detect the radial displacement of the rotor shaft 113, that is, the rotating body 103 fixed thereto, and send it to the control device 195.

[0035] In the control device 195, for example, a compensation circuit with 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 The amplifier circuit 150 (described later) shown performs excitation control on the upper radial electromagnet 104 based on this excitation control command signal to adjust the upper radial position of the rotor shaft 113.

[0036] Moreover, the rotor shaft 113 is formed of a high magnetic permeability material (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. This adjustment is performed independently in the X-axis direction and the Y-axis direction. In addition, the lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same way as the upper radial electromagnet 104 and the upper radial sensor 107, and the lower radial position of the rotor shaft 113 is adjusted in the same way as the upper radial position.

[0037] Furthermore, axial electromagnets 106A and 106B are arranged to sandwich a disc-shaped metal disc 111 provided at the lower part of the rotor shaft 113 from above and below. The metal disc 111 is made of a high magnetic permeability material such as iron. An axial sensor 109 is provided to detect the axial displacement of the rotor shaft 113, and its axial position signal is configured to be sent to the control device 195.

[0038] Moreover, in the control device 195, a compensation circuit with, for example, 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. The amplifier circuit 150 performs excitation control on the axial electromagnet 106A and the axial electromagnet 106B respectively based on these excitation control command signals. The axial electromagnet 106A attracts the metal disc 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disc 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0039] In this way, the control device 195 appropriately adjusts the magnetic force exerted by the axial electromagnets 106A and 106B on the metal disc 111, causing the rotor shaft 113 to be magnetically levitated axially and held in space in a non-contact manner. In addition, the amplifier circuit 150 for performing excitation control on these upper radial electromagnets 104, lower radial electromagnets 105, and axial electromagnets 106A and 106B will be described later.

[0040] On the other hand, the motor 121 includes a plurality of magnetic poles arranged circumferentially so as to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 195 to rotationally drive the rotor shaft 113 via the electromagnetic force acting between them. In addition, a rotational speed sensor such as a Hall element, an analyzer, an encoder, etc. (not shown) is installed in the motor 121, and the rotational speed of the rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

[0041] Furthermore, for example, a phase sensor (not shown) is installed near the lower radial sensor 108 to detect the rotation phase of the rotor shaft 113. In the control device 195, the detection signals of this phase sensor and the rotational speed sensor are used together to detect the position of the magnetic poles.

[0042] A plurality of stationary vanes 123 (123a, 123b, 123c...) are arranged with a slight gap from the rotating vanes 102 (102a, 102b, 102c...). The turbine pump section is composed of these multi-stage rotating vanes 102 and multi-stage stationary vanes 123. The rotating vanes 102 (102a, 102b, 102c...) respectively transfer the molecules of the exhaust gas downward by means of collision, so they are formed by inclining at a specified angle from a plane perpendicular to the axis of the rotor shaft 113. The stationary vanes 123 (123a, 123b, 123c...) are made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components, for example.

[0043] In addition, the stationary vanes 123 are also formed by inclining at a specified angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged so as to be staggered from the levels of the rotating vanes 102 toward the inside of the outer cylinder 127. Moreover, the outer peripheral ends of the stationary vanes 123 are supported in a state of being inserted between a plurality of stacked stationary vane spacers 125 (125a, 125b, 125c...).

[0044] The stationary vane spacers 125 are annular members, and are made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components, for example. An outer cylinder 127 is fixed to the outer periphery of the stationary vane spacers 125 with a slight gap. A base portion 129 is provided at the bottom of the outer cylinder 127 (more specifically, the bottom of the outer wall 126). An exhaust port 133 is formed above the base portion 129 and communicates with the outside. The exhaust gas that enters from the chamber (vacuum chamber) side through the suction port 101 and is transferred toward the base portion 129 is conveyed to the exhaust port 133.

[0045] Furthermore, according to the use of the turbomolecular pump 100, a threaded spacer 131 that functions as a screw groove pump section is arranged between the lower part of the stationary vane spacer 125 and the base portion 129. The threaded spacer 131 is a cylindrical member made of metals such as aluminum, copper, stainless steel, iron, or alloys containing these metals as components, and a plurality of spiral screw grooves 131a are engraved on its inner peripheral surface. The direction of the spiral of the screw grooves 131a is the direction in which the molecules of the exhaust gas are transferred toward the exhaust port 133 when the molecules of the exhaust gas move in the rotation direction of the rotating body 103. A cylindrical portion 102d hangs down at the lowermost part of the rotating body 103 that is continuous with the rotating vanes 102 (102a, 102b, 102c...). The outer peripheral surface of the cylindrical portion 102d protrudes cylindrically and toward the inner peripheral surface of the threaded spacer 131, and approaches the inner peripheral surface of the threaded spacer 131 with a specified gap. The exhaust gas transferred to the screw grooves 131a by the rotating vanes 102 and the stationary vanes 123 is conveyed to the base portion 129 while being guided by the screw grooves 131a.

[0046] More specifically, the exhaust gas guided by the threaded groove 131a is conveyed to the annular space 135 formed above the base portion 129, and is discharged to the outside through the exhaust port 133 while circulating in the annular space 135. The annular space 135 is an annular space partitioned by the cylindrical portion 102d of the rotating body 103, the threaded spacer 131, the heater spacer 153, and the base portion 129.

[0047] Here, the heater spacer 153 for fixing parts is a cylindrical member, and is integrally formed with the threaded spacer 131 in the present embodiment. That is, the heater spacer 153 constitutes a part of the threaded spacer 131. Of course, the heater spacer 153 and the threaded spacer 131 may also be formed separately. The heater spacer 153 is made of a metal such as aluminum or stainless steel, for example. A heater 190 as a heating mechanism is inserted into the heater spacer 153, and the threaded spacer 131 is heated via the heater spacer 153 by the heat generated by the heater 190. In addition, the exhaust gas flowing through the annular space 135 is also heated by the heater 190. Thereby, the generation of deposits due to the temperature drop of the exhaust gas is suppressed. In addition, the inner spacer 154 is a cylindrical member made of a metal such as stainless steel, for example, and insulates between the water-cooled spacer 128 and the fixed vane spacer 125 on the lower side than the water-cooled spacer 128.

[0048] The base portion 129 is a disc-shaped member constituting the base of the turbo molecular pump 100, and is generally made of a metal such as iron, aluminum, or stainless steel. Since the base portion 129 physically holds the turbo molecular pump 100 and also functions as a heat conduction path, it is preferably made of a metal such as iron, aluminum, or copper that has rigidity and a relatively high thermal conductivity.

[0049] In this structure, if the rotating blade 102 and the rotor shaft 113 are rotationally driven together by the motor 121, the exhaust gas is sucked from the chamber through the suction port 101 by the action of the rotating blade 102 and the fixed blade 123. The rotational speed of the rotating blade 102 is usually 20,000 rpm to 90,000 rpm, and the peripheral speed at the end of the rotating blade 102 reaches 200 m / s to 400 m / s. The exhaust gas sucked from the suction port 101 is transferred to the base portion 129 through between the rotating blade 102 and the fixed blade 123. At this time, due to the frictional heat generated when the exhaust gas contacts the rotating blade 102, the conduction of heat generated by the motor 121, etc., the temperature of the rotating blade 102 rises, but this heat is transferred to the fixed blade 123 side by radiation or conduction by the gas molecules of the exhaust gas, etc.

[0050] The fixed vane spacers 125 are joined to each other at their outer circumferential portions, and transfer heat received by the fixed vanes 123 from the rotating vanes 102, frictional heat generated when the exhaust gas contacts the fixed vanes 123, etc. to the outside.

[0051] In addition, in the above description, it is assumed that the threaded spacer 131 is disposed on the outer circumference of the cylindrical portion 102d of the rotating body 103, and the thread groove 131a is formed on the inner circumferential surface of the threaded spacer 131. However, conversely, there is also a case where a thread groove is formed on the outer circumferential surface of the cylindrical portion 102d, and a spacer having a cylindrical inner circumferential surface is disposed around it.

[0052] Furthermore, depending on the use of the turbo molecular pump 100, there is also a case where the periphery of the electrical component portion is covered with the stator column 122, and the inside of the stator column 122 is maintained at a specified pressure with a cleaning gas so that the gas sucked from the suction port 101 does not invade the electrical component portion composed of the upper side radial electromagnet 104, the upper side radial sensor 107, the motor 121, the lower side radial electromagnet 105, the lower side radial sensor 108, the axial electromagnets 106A, 106B, the axial sensor 109, etc.

[0053] In this case, a pipe (not shown) is disposed in the base portion 129, and the cleaning gas is introduced through this pipe. The introduced cleaning gas is sent to the exhaust port 133 through the gaps between the protection bearing 120 and the rotor shaft 113, between the rotor and the stator of the motor 121, and between the stator column 122 and the inner circumferential cylindrical portion of the rotating vane 102. In addition, as Figure 1 shown, the stator column 122 stands at the central position of the base portion 129. In addition, in the present embodiment, a water cooling pipe 149 as a cooling mechanism is provided in the base portion 129. By supplying cooling water to the water cooling pipe 149, the base portion 129 and the stator column 122 are maintained at an appropriate temperature.

[0054] Here, the turbo molecular pump 100 needs to be controlled based on the determination of the model and the inherent parameters (for example, various characteristics corresponding to the model) that are separately adjusted. In order to store the control parameters, the above-mentioned turbo molecular pump 100 has an electronic circuit portion 141 in its main body. The electronic circuit portion 141 is composed of semiconductor memories such as EEP-ROM and electronic components for accessing them, a substrate 143 for mounting them, etc. The electronic circuit portion 141 is housed below, for example, a rotation speed sensor (not shown) near the center of the base portion 129 that constitutes the turbo molecular pump 100, and is sealed by an airtight bottom cover 145.

[0055] In addition, in the manufacturing process of semiconductors, among the process gases introduced into the chamber, there are process gases that become solid if their pressure becomes higher than a specified value or their temperature becomes lower than a specified value. Inside the turbo molecular pump 100, the pressure of the exhaust gas is the lowest at the suction port 101 and the highest at the exhaust port 133. If, during the transfer of the process gas from the suction port 101 to the exhaust port 133, its pressure becomes higher than the specified value or its temperature becomes lower than the specified value, the process gas becomes solid-like and adheres and accumulates inside the turbo molecular pump 100.

[0056] For example, according to the vapor pressure curve, when SiCl4 is used as a process gas in an Al etching apparatus, at low vacuum (760 [torr] to 10 -2 [torr]) and low temperature (about 20 [°C]), solid products (such as AlCl3) precipitate and adhere and accumulate inside the turbo molecular pump 100. Thus, if the precipitates of the process gas accumulate inside the turbo molecular pump 100, the accumulated material narrows the pump flow path, causing a decline in the performance of the turbo molecular pump 100. Moreover, the aforementioned products are in a state where they are prone to solidifying and adhering at parts with higher pressure near the exhaust port 133 and near the threaded spacer 131.

[0057] Therefore, to solve this problem, conventionally, a heater (not shown) and a ring-shaped water-cooling pipe 149 are wound around the outer periphery of the base portion 129, etc., and for example, a temperature sensor (such as a thermistor) not shown is buried in the base portion 129, and based on the signal of this temperature sensor, heating of the heater and control of cooling by the water-cooling pipe 149 are performed (hereinafter referred to as TMS. TMS; Temperature Management System, temperature management system) to keep the temperature of the base portion 129 at a certain high temperature (set temperature).

[0058] Next, regarding the turbo molecular pump 100 configured as such, an amplifier circuit 150 for exciting and controlling the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A, 106B will be described. In Figure 2 shows the circuit diagram of this amplifier circuit 150.

[0059] In Figure 2 one end of the electromagnet coil 151 that constitutes the upper radial electromagnet 104, etc. is connected to the positive electrode 171a of the power supply 171 via the transistor 161, and in addition, 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. Moreover, the transistors 161, 162 are so-called power MOSFETs and have a structure in which a diode is connected between their source and drain.

[0060] At this time, the cathode terminal 161a of the diode of the transistor 161 is connected to the positive electrode 171a, and the anode terminal 161b is connected to one end of the electromagnet coil 151. In addition, the cathode terminal 162a of the diode of the transistor 162 is connected to the current detection circuit 181, and the anode terminal 162b is connected to the negative electrode 171b.

[0061] On the other hand, the cathode terminal 165a of the diode 165 for current regeneration is connected to one end of the electromagnet coil 151, and its anode terminal 165b is connected to the negative electrode 171b. In addition, similarly, the cathode terminal 166a of the diode 166 for current regeneration is connected to the positive electrode 171a, and its anode terminal 166b is connected to the other end of the electromagnet coil 151 via the current detection circuit 181. Moreover, the current detection circuit 181 is composed of, for example, a Hall sensor type current sensor and a resistance element.

[0062] The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, in the case where the magnetic bearing is 5-axis controlled and there are a total of 10 electromagnets 104, 105, 106A, and 106B, amplifier circuits 150 of the same configuration are respectively constituted for the electromagnets, and 10 amplifier circuits 150 are connected in parallel to the power supply 171.

[0063] Furthermore, the amplifier control circuit 191 is composed of, for example, a digital signal processor unit (hereinafter referred to as the DSP unit) (not shown) of the control device 195, and the amplifier control circuit 191 switches the on / off states of the transistors 161 and 162.

[0064] The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (a signal reflecting this current value is referred to as the current detection signal 191c) with a prescribed current command value. Then, based on the comparison result, the magnitudes of the pulse widths (pulse width times Tp1 and Tp2) generated within one cycle of the PWM control, that is, the control cycle Ts, are determined. As a result, gate drive signals 191a and 191b having such pulse widths are output from the amplifier control circuit 191 to the gate terminals of the transistors 161 and 162.

[0065] In addition, when passing through the resonance point during the acceleration operation of the rotational speed of the rotating body 103, when interference occurs during the constant speed operation, etc., position control of the rotating body 103 under high speed and strong force is required. Therefore, a high voltage of about 50 V is used as the power supply 171 in order to enable a sharp increase (or decrease) in the current flowing through the electromagnet coil 151. In addition, between the positive electrode 171a and the negative electrode 171b of the power supply 171, a capacitor (not shown) is usually connected for stabilizing the power supply 171.

[0066] In this structure, if both transistors 161 and 162 are turned on, the current flowing through the electromagnet coil 151 (hereinafter referred to as the electromagnet current iL) increases, and if both are turned off, the electromagnet current iL decreases.

[0067] In addition, if one of the transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is maintained. Moreover, by flowing the flywheel current through the amplifier circuit 150 in this way, the hysteresis loss in the amplifier circuit 150 is reduced, and the power consumption of the entire circuit can be suppressed to a low level. In addition, by controlling the transistors 161 and 162 in this way, high-frequency noise such as high harmonics generated in the turbo molecular pump 100 can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet coil 151 can be detected.

[0068] That is, when the detected current value is smaller than the current command value, as Figure 3 shown, both transistors 161 and 162 are turned on only once for a time corresponding to the pulse width time Tp1 in the control cycle Ts (for example, 100 μs). Therefore, during this period, the electromagnet current iL increases toward the current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.

[0069] On the other hand, when the detected current value is larger than the current command value, as Figure 4 shown, both transistors 161 and 162 are turned off only once for a time corresponding to the pulse width time Tp2 in the control cycle Ts. Therefore, during this period, the electromagnet current iL decreases toward the current value iLmin (not shown) that can be regenerated from the negative electrode 171b to the positive electrode 171a via the diodes 165 and 166.

[0070] Moreover, in either case, one of the transistors 161 and 162 is turned on after the elapse of the pulse width times Tp1 and Tp2. Therefore, during this period, the flywheel current is maintained in the amplifier circuit 150.

[0071] Next, the characteristic parts of the turbo molecular pump 100 according to this embodiment will be described in detail. Figure 5 It is a main part enlarged view showing an enlarged view of part A of Figure 1 . As Figure 5As shown, in the present embodiment, a water-cooled spacer 128 is disposed at a position between the uppermost stage and the lowermost stage among the multi-stage stationary vanes 123. The water-cooled spacer 128 has a function as a stationary vane spacer 125 for axially positioning the stationary vanes 123, and also serves to cool the stationary vanes 123 and reduce the temperature of the rotating blades 102 by radiant heat. As a result, not only the water-cooled spacer 128 but also the gas in contact with the stationary vanes 123 is cooled.

[0072] The water-cooled spacer 128 includes a cooling pipe 110 and a temperature sensor 185 as described above. The cooling pipe 110 is provided on the outer peripheral portion of the water-cooled spacer 128. The temperature sensor 185 is provided radially inside the cooling pipe 110 and in the vicinity of the cooling pipe 110. More specifically, the temperature sensor 185 is provided at a position that is at a distance X1 from the inner peripheral portion (the portion in contact with the gas flow path F1) of the water-cooled spacer 128 and at a position that is radially inside the cooling pipe 110 by a distance Y1. Moreover, the distance X1 is considerably longer than the distance Y1. That is, the temperature sensor 185 is provided at a position away from the gas flow path F1 and at a position close to the cooling pipe 110.

[0073] In addition, the ratio of the distance X1 to the distance Y1 can be arbitrarily set based on specifications such as the material of the water-cooled spacer 128, the flow rate and temperature of the cooling water flowing through the cooling pipe 110, and the flow rate and temperature of the gas flowing through the gas flow path F1. For example, it is preferably set within a range of about 2:1 to 10:1.

[0074] The water-cooled spacer 128 is disposed between the outer cylinder 127 and the outer wall 126 and is fixed by bolts 115. In addition, a heat insulating ring 155 is interposed between the water-cooled spacer 128 and the outer wall 126. The heat insulating ring 155 insulates between the water-cooled spacer 128 and the outer wall 126. In addition, O-rings 192 are installed between the outer cylinder 127 and the water-cooled spacer 128 and between the inner spacer 154 and the water-cooled spacer 128 to maintain airtightness.

[0075] Next, the shape of the water-cooled spacer 128 will be described in detail. Figure 6 is Figure 5 a detailed longitudinal sectional view of the water-cooled spacer 128 shown. As Figure 6 shown, the water-cooled spacer 128 includes a support portion 128a and a protruding portion 128b. The support portion 128a supports the stationary vane spacer 125 adjacent in the axial direction and axially (vertically) positions the adjacent stationary vanes 123. The protruding portion 128b is provided to protrude radially outward from the support portion 128a and has a tapered portion 128b-1 and a body portion 128b-2.

[0076] The tapered portion 128b-1 is inclined in a shape along the upper end side of the inner spacer 154. Further, a stepped portion 128c which is cut off in an annular shape is formed on the upper surface of the tapered portion 128b-1.

[0077] On the upper surface of the body portion 128b-2, an annular groove portion 128d is provided at the end portion on the outer peripheral side, and a cooling pipe 110 is disposed in the groove portion 128d. Further, one elongated mounting hole 128e is provided along the axial direction on the lower surface of the body portion 128b-2. The mounting hole 128e is for inserting a temperature sensor 185. In addition, the reference numeral 116 is a cover for covering the cooling pipe 110.

[0078] In this way, the water-cooled spacer 128 which is integrally formed in a ring shape has a structure in which the body portion 128b-2 extends downward and radially outward from the support portion 128a via the tapered portion 128b-1. Moreover, the thickness T2 of the protruding portion 128b is larger than the thickness (axial length) T1 of the support portion 128a. More specifically, the thickness T2 is about 2.5 times the thickness T1. Thus, the water-cooled spacer 128 achieves high rigidity by means of the thick-walled protruding portion 128b. According to this structure, if the water-cooled spacer 128 is disposed at Figure 5 the position, the tapered portion 128b-1 covers the outside of the inner spacer 154.

[0079] Next, the effects of the present embodiment configured as described above will be described.

[0080] The turbo molecular pump 100 according to the present embodiment includes a water-cooled spacer 128. The water-cooled spacer 128 has a cooling pipe 110 and a temperature sensor 185. Moreover, the temperature sensor 185 is provided near the cooling pipe 110.

[0081] By opening / closing an unillustrated valve based on temperature data from the temperature sensor 185, the cooling water flowing into the cooling pipe 110 is controlled. When the temperature inside the turbo molecular pump 100 rises, the valve of the cooling pipe 110 is opened to control the temperature of the water-cooled spacer 128, particularly the temperature of the inner peripheral portion (the portion in contact with the gas flow path F1) of the water-cooled spacer 128.

[0082] In the temperature control system as described above, overshoot occurs with respect to the target temperature. However, since the temperature sensor 185 is located near the cooling pipe 110 as described above, the temperature of the cooling pipe 110 can be detected with high precision. As a result, the control device 195 can control the temperature of the inner peripheral portion of the water-cooled spacer 128 that comes into contact with the gas inside the turbo molecular pump 100 with high precision based on the temperature data from the temperature sensor 185. In addition, since the distance X1 is longer than the distance Y1, with respect to the temperature change of the cooling pipe 110, overshoot is less likely to occur in the temperature control of the inner peripheral portion of the water-cooled spacer 128. That is, the temperature change of the water-cooled spacer 128 corresponding to the temperature change caused by the cooling pipe 110 is made sluggish, and it is easy to keep the temperature of the inner peripheral portion of the water-cooled spacer 128 at a constant temperature. Thus, according to the present embodiment, the temperature of the inner peripheral portion of the water-cooled spacer 128 connected to the gas flow path F1 can be stably controlled without impairing the cooling effect of the cooling pipe 110. In addition, since the temperature of the inner peripheral portion of the water-cooled spacer 128 is stable, the cooling state of the stationary blade 123 is also stable. As a result, the temperature of the rotating blade 102 is also stable.

[0083] In addition, the water-cooled spacer 128 is made of a member having a higher conductivity than the outer cylinder 127 and the outer wall 126, specifically, made of aluminum. The purpose is to use a member with a higher thermal conductivity, and it is easy to change the temperature of the water-cooled spacer 128 with a smaller amount of cooling. However, by making the distance X1 longer than the distance Y1, overshoot can be reduced in the inner peripheral portion of the water-cooled spacer 128 in contact with the gas flow path F1, and the target temperature can be reached more quickly.

[0084] That is, according to the present embodiment, by detecting the temperature change of the cooling pipe 110 with high precision by the temperature sensor 185 disposed near the cooling pipe 110, while controlling to suppress the temperature change of the cooling pipe 110, it is easy to control the temperature of the water-cooled spacer 128 to the target temperature. In addition, by separating the cooling pipe 110 and the gas flow path F1 by the distance X1, even when a member with a higher thermal conductivity is used for the water-cooled spacer 128, the rapid temperature change of the cooling pipe 110 is less likely to be transmitted to the inner peripheral surface of the water-cooled spacer 128 in contact with the gas flow path F1. And by making the water-cooled spacer 128 a member having a high thermal conductivity such as aluminum, even if the cooling pipe 110 is separated from the gas flow path F1, the temperature of the inner peripheral surface of the water-cooled spacer 128 in contact with the gas flow path F1 can be cooled to the desired temperature.

[0085] In addition, since the temperature sensor 185 is provided on the radially inner side of the cooling pipe 110, there is also an advantage that the temperature of the cooling pipe 110 can be detected with high precision without being affected by the temperature of the surrounding parts of the water-cooled spacer 128.

[0086] In addition, the temperature of the cooling water flowing into the cooling pipe 110 is arbitrary. As described above, the water-cooled spacer 128 is a component that cools the stationary blades 123 and cools the rotating blades 102 by radiant heat. Therefore, any temperature suitable for cooling the rotating blades 102 is acceptable. Thus, depending on the temperature inside the turbo molecular pump 100, the temperature of the cooling water can be less than 100 degrees or 100 degrees or more.

[0087] In addition, since the water-cooled spacer 128 includes a support portion 128a and a protruding portion 128b and the protruding portion 128b has a thicker wall than the support portion 128a, deformation of the water-cooled spacer 128, particularly bending deformation in the axial direction, can be prevented. Further, since the protruding portion 128b is configured to cover the outer peripheral side of the lower stationary blade spacer 125 in a shape (conical shape) imitating the upper portion of the inner spacer 154, the ineffective space formed in the upper portion of the inner spacer 154 can be utilized, and the rigidity of the water-cooled spacer 128 can be increased without increasing the axial dimension. If a structure is adopted in which the protruding portion 128b extends upward from the support portion 128a to increase the rigidity of the water-cooled spacer 128, the size of the turbo molecular pump 100 as a whole increases in the axial direction. However, with the shape of the present embodiment, this can be achieved without increasing the size.

[0088] In addition, since a structure is adopted in which a heater 190 is provided in the heater spacer 153, the temperature of the exhausted gas can be controlled with higher precision. The heater spacer 153 is a fixed part that is disposed on the downstream side of the plurality of rotating blades 102 and the plurality of stationary blades 123 and forms a part of the screw groove pump section.

[0089] (Second Embodiment)

[0090] Next, a turbo molecular pump according to a second embodiment of the present invention will be described. Figure 7 is a longitudinal sectional view of a turbo molecular pump 200 according to a second embodiment of the present invention, Figure 8 is Figure 7 a main part enlarged view showing an enlarged B portion of

[0091] As shown in these figures, in the second embodiment, the structure of the water-cooled spacer is different from that of the first embodiment. Specifically, in the first embodiment, the water-cooled spacer 128 is disposed between the uppermost stage and the lowermost stage of the multi-stage stationary blades 123, while in the second embodiment, the water-cooled spacer 228 is disposed at the position of the lowermost stage of the multi-stage stationary blades 123. Therefore, the shapes of the water-cooled spacers are different between the first embodiment and the second embodiment.

[0092] The water-cooled spacer 228 is also made of aluminum as in the first embodiment, and includes a cooling pipe 110 and a temperature sensor 185. Compared with the first embodiment, the cooling pipe 110 is disposed on the radially inner side of the outer peripheral portion of the water-cooled spacer 228. Specifically, the cooling pipe 110 is disposed at a position separated by a distance X2 from the inner peripheral portion of the water-cooled spacer 228 (the side closer to the gas flow path F2). In addition, the temperature sensor 185 is disposed on the radially outer side of the cooling pipe 110, near the cooling pipe 110. More specifically, the temperature sensor 185 is disposed at a position separated by a distance Y2 from the cooling pipe 110 on the radially outer side. Moreover, the distance X2 is slightly longer than the distance Y2.

[0093] In addition, the ratio of the distance X2 to the distance Y2 can be arbitrarily set based on specifications such as the material of the water-cooled spacer 228, the flow rate and temperature of the cooling water flowing through the cooling pipe 110, and the flow rate and temperature of the gas flowing through the gas flow path F2, but it is preferably set within a range of about 1.5:1 to 3:1, for example.

[0094] The water-cooled spacer 228 is disposed between the outer cylinder 127 and the base portion 129 and is fixed by bolts 115. In addition, O-rings 192 are fitted between the outer cylinder 127 and the water-cooled spacer 228 and between the base portion 129 and the water-cooled spacer 228 to maintain airtightness.

[0095] Next, the shape of the water-cooled spacer 228 will be described in detail. Figure 9 It is a longitudinal sectional view showing Figure 8 the details of the water-cooled spacer 228 shown. As Figure 9 shown, the water-cooled spacer 228 includes a support portion 228a and a protruding portion 228b. The support portion 228a supports the fixed vane spacer 125 adjacent in the axial direction and positions the adjacent fixed vane 123 in the axial direction (vertical direction). The protruding portion 128b is provided so as to protrude radially outward from the support portion 128a. Moreover, the cross section of the water-cooled spacer 228 is substantially L-shaped by means of the support portion 228a and the protruding portion 228b.

[0096] In the support portion 228a, a step portion 228c for fitting the O-ring 192 is provided. In addition, on the lower surface of the protruding portion 228b, an annular groove portion 228d and a mounting hole 228e are provided. The cooling pipe 110 is installed in the groove portion 228d, and the temperature sensor 185 is installed in the mounting hole 228e.

[0097] According to the second embodiment, the same effects as those of the first embodiment are achieved. In addition, in the second embodiment, since the water-cooled spacer 228 is arranged in the lowermost stage of the multi-stage stationary vanes 123, the water-cooled spacer 228 can be directly fixed to the base portion 129. As a result, there is no need for the outer wall 126 as in the first embodiment, and the structure can be simplified.

[0098] In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. All technical matters included in the technical idea described in the claims are the objects of the present invention. The foregoing embodiments show preferred examples, but those skilled in the art can implement various alternative examples, correction examples, modification examples, combination examples, or improvement examples based on the content disclosed in this specification, and these are included in the technical scope described in the appended claims.

[0099] Explanation of Reference Numerals

[0100] 100, 200 Turbomolecular pump (vacuum pump)

[0101] 102 (102a, 102b, 102c) Rotating vane

[0102] 102d Cylindrical portion

[0103] 103 Rotating body

[0104] 113 Rotor shaft

[0105] 116 Cover

[0106] 122 Stator column

[0107] 123 (123a, 123c, 123c) Stationary vane

[0108] 125 (125a, 125b, 125c) Stationary vane spacer

[0109] 126 Outer wall (housing)

[0110] 127 Outer cylinder (housing)

[0111] 128, 228 Water-cooled spacer (specific spacer)

[0112] 128a, 228a Support portion

[0113] 128b, 228b Protruding portion

[0114] 128b-1 Tapered portion

[0115] 128b-2 Body portion

[0116] 128c and 228c step difference parts

[0117] 128d and 228d circular grooves

[0118] 128e and 228e mounting holes

[0119] 129 base part

[0120] 131 threaded spacer (threaded groove pump part)

[0121] 133 exhaust port

[0122] 153 heater spacer (fixed part)

[0123] 154 inner spacer

[0124] 155 heat insulation ring

[0125] 185 temperature sensor

[0126] 190 heater (heating mechanism)

[0127] 192 O-ring

[0128] 195 control device

Claims

1. A vacuum pump, comprising: A housing; A rotor shaft rotatably supported inside the housing; Multiple rotating vanes fixed to the rotor shaft and capable of rotating together with the rotor shaft; Multiple fixed vanes fixed to the housing and arranged between the multiple rotating vanes; and Multiple fixed vane spacers supporting the multiple fixed vanes; Characterized in that It comprises: A temperature adjustment mechanism provided in a specific spacer of a certain stage among the multiple fixed vane spacers to adjust the temperature of the specific spacer; and A temperature sensor provided at a position closer to the temperature adjustment mechanism than the gas flow path of the turbo pump section composed of the multiple rotating vanes and the multiple fixed vanes.

2. The vacuum pump according to claim 1, characterized in that The housing includes an outer cylinder arranged on the outer peripheral side of the rotor shaft and a base portion arranged below the outer cylinder; The specific spacer is made of a component having a higher thermal conductivity than the outer cylinder.

3. The vacuum pump according to claim 2, characterized in that The specific spacer is made of aluminum.

4. The vacuum pump according to claim 1, characterized in that The specific spacer is arranged between the uppermost stage and the lowermost stage of the multiple fixed vanes.

5. The vacuum pump according to claim 4, characterized in that The specific spacer covers the outer peripheral side of the fixed vane spacers adjacent in the axial direction.

6. The vacuum pump according to claim 5, characterized in that The specific spacer has: a support portion supporting the fixed vane spacers adjacent in the axial direction; and an extending portion extending radially outward from the support portion to cover the outer peripheral side of the fixed vane spacer; The thickness of the extending portion is larger than the thickness of the support portion.

7. The vacuum pump according to claim 1, characterized in that The temperature sensor is provided at a position between the gas flow path in the radial direction and the temperature adjustment mechanism.

8. The vacuum pump according to any one of claims 1 to 7, characterized in that It includes a fixed part arranged on the downstream side of the multiple rotating vanes and the multiple fixed vanes and constituting a part of the screw groove pump section; The fixed part is heated by a heating mechanism.

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