JP7463324B2 - Vacuum pump and heat transfer suppressing member for vacuum pump - Google Patents

Description

The present invention relates to a vacuum pump and a heat transfer suppression member for the vacuum pump.

As background art in this technical field, for example, Patent Document 1 describes a turbomolecular pump that can prevent the accumulation of reaction products on a cylindrical stator and suppress the transfer of heat by radiation from the cylindrical stator to members surrounding the cylindrical stator.

Specifically, the turbomolecular pump described in Patent Document 1 includes a pump rotor having rotor blades and a rotor cylindrical portion, a stationary vane facing the rotor blades, a cylindrical stator facing the rotor cylindrical portion, a base that houses the cylindrical stator, and a stator heating portion that heats the cylindrical stator. The emissivity of the outer surface of the cylindrical stator and the emissivity of the outer surfaces of the rotor cylindrical portion, base, rotor blades, and stationary vanes that face the cylindrical stator, which are peripheral members that face the cylindrical stator, are smaller than the emissivity of the outer surface of the rotor blades that faces the stationary vanes.

JP 2015-229949 A

However, in Patent Document 1, the peripheral components of the cylindrical stator themselves are made of a low-emissivity material, and the external surfaces of the peripheral components are subjected to a specified surface treatment to reduce the emissivity. Therefore, in Patent Document 1, the peripheral components of the cylindrical stator must be designed as dedicated parts, which results in low freedom of design and a lack of versatility.

In addition to heat transfer by radiation, heat can also be transferred to the peripheral components of the cylindrical stator through gas flowing around the peripheral components of the cylindrical stator, and the countermeasures in Patent Document 1 were not sufficient in some cases. This problem was particularly noticeable in areas where the gap between the cylindrical stator and the peripheral components of the cylindrical stator was narrow.

Therefore, the main objective of the present invention is to provide a vacuum pump that increases the degree of freedom in the design of the peripheral components of the stator, is highly versatile, and can further suppress heat transfer.

In order to achieve the above-mentioned object, one aspect of the present invention is a vacuum pump comprising a base, a stator column erected at a central position of the base, a rotor held rotatably relative to the stator column, a stator portion arranged on the outer periphery of the rotor, a heating means for heating the stator portion, and a partition portion arranged between the base and the stator portion and forming a flow path through which exhaust gas flows together with the stator portion, wherein at least a portion of the partition portion has an opposing region that faces a specific region formed on the base, the stator column, and the rotor with a predetermined gap therebetween, and the opposing region is provided with a heat transfer suppression member that suppresses the transfer of heat from the opposing region to the specific region while not being in physical contact with the specific region.

In the above configuration, it is preferable that the heat transfer suppression member is made of a material with a lower thermal conductivity than the partition wall.

In the above configuration, it is preferable that the heat transfer suppression member is surface-treated so that it has a lower emissivity than the partition wall.

In addition, in the above configuration, it is preferable to provide a cooling means for cooling the base and the stator column.

In addition, in the above configuration, it is preferable that the heat transfer suppression member has a cylindrical body portion and a flange portion extending radially outward from one end side of the body portion.

In the above configuration, it is preferable that the axial length of the body portion is greater than the radial length of the flange portion.

In addition, in the above configuration, it is preferable that the partition has a step portion that abuts against the flange portion, and that the flange portion and the partition portion are flush with each other when the flange portion abuts against the step portion.

In order to achieve the above-mentioned object, another aspect of the present invention is a heat transfer suppression member for a vacuum pump which is used in a vacuum pump including a base, a stator column erected at a central position of the base, a rotor held rotatably relative to the stator column, a stator portion arranged on the outer periphery of the rotor, heating means for heating the stator portion, and a partition portion arranged between the base and the stator portion and which, together with the stator portion, forms a flow path through which exhaust gas flows, and which is attached separately to the partition portion, wherein the heat transfer suppression member, when attached to the partition portion, suppresses heat transfer from the partition portion to the base, the stator column, and the rotor in a state of physical non-contact.

The present invention provides a vacuum pump that increases the degree of freedom in designing the peripheral components of the stator, is highly versatile, and can further suppress heat transfer. Problems, configurations, and effects other than those described above will become clear from the description of the embodiments below.

1 is a vertical sectional view of a turbomolecular pump according to a first embodiment of the present invention; FIG. 2 is a circuit diagram of an amplifier circuit of the turbomolecular pump shown in FIG. 1 . 6 is a time chart showing the control of the amplifier control circuit when a current command value is larger than a detection value. 6 is a time chart showing the control of the amplifier control circuit when a current command value is smaller than a detection value. FIG. 2 is an enlarged view of a main part of part A in FIG. 1 . FIG. 5 is a vertical sectional view of a turbomolecular pump according to a second embodiment of the present invention. FIG. 7 is an enlarged view of a main part of part B in FIG. 6 . FIG. 11 is a vertical sectional view of a turbomolecular pump according to a third embodiment of the present invention. FIG. 9 is an enlarged view of a main part of part C in FIG. 8 .

Below, an embodiment of a vacuum pump according to the present invention will be described with reference to the drawings, taking a turbomolecular pump as an example.

First Embodiment
A longitudinal cross-sectional view of this turbomolecular pump 100 is shown in FIG. 1. In FIG. 1, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Inside the outer cylinder 127, a rotor 103 is provided with a plurality of rotors 102 (102a, 102b, 102c, ...) which are turbine blades for sucking and exhausting gas, formed radially on the periphery in multiple stages. A rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is levitated and supported in the air and positionally controlled by, for example, a five-axis controlled magnetic bearing. The rotor 103 is generally made of a metal such as aluminum or an aluminum alloy. As shown in FIG. 1, in this embodiment, the outer cylinder 127 is configured to be divided into two parts, upper and lower, but the present invention is not limited to this configuration. An integrated outer cylinder may also be used.

The upper radial electromagnets 104 are arranged in pairs on the X-axis and Y-axis. Four upper radial sensors 107 are provided in close proximity to the upper radial electromagnets 104 and corresponding to each of the upper radial electromagnets 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on the change in inductance of the conductive windings, which changes according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send it to the control device 200.

In this 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 the position signal detected by the upper radial sensor 107, and the amplifier circuit 150 (described later) shown in FIG. 2 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

The rotor shaft 113 is made of a material with high magnetic permeability (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. 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 adjust the lower radial position of the rotor shaft 113 in the same manner as the upper radial position.

Furthermore, axial electromagnets 106A and 106B are arranged above and below a circular metal disk 111 provided at the bottom of rotor shaft 113. Metal disk 111 is made of a high magnetic permeability material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and the axial position signal is sent to control device 200.

In the control device 200, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

In this way, the control device 200 appropriately adjusts the magnetic force that the axial electromagnets 106A and 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. The amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

On the other hand, the motor 121 has multiple magnetic poles arranged circumferentially to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 so as to rotate the rotor shaft 113 via electromagnetic forces acting between the magnetic poles and the rotor shaft 113. In addition, the motor 121 incorporates a rotational speed sensor, such as a Hall element, resolver, or encoder (not shown), and the rotational speed of the rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

Furthermore, 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 uses the detection signals of both this phase sensor and the rotation speed sensor to detect the position of the magnetic pole.

Multiple fixed blades 123 (123a, 123b, 123c...) are arranged with a small gap between the rotor blades 102 (102a, 102b, 102c...). The rotor blades 102 (102a, 102b, 102c...) are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward by collision. The fixed blades 123 (123a, 123b, 123c...) are made of metals such as aluminum, iron, stainless steel, copper, etc., or alloys containing these metals as components.

The fixed blades 123 are also formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged in a staggered manner with the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral end of the fixed blades 123 is supported by being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, etc.).

The fixed wing spacer 125 is a ring-shaped member, and is made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a small gap between them. A base portion 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed above the base portion 129 and is connected to the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) side and is transported toward the base portion 129 is sent to the exhaust port 133.

Depending on the application of the turbomolecular pump 100, a threaded spacer 131 is disposed between the lower part of the fixed vane spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical member made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has a plurality of helical thread grooves 131a engraved on its inner peripheral surface. The helical direction of the thread groove 131a is the direction in which the molecules of the exhaust gas are transported toward the exhaust port 133 when they move in the rotation direction of the rotor 103. A cylindrical part 102d hangs down from the lowest part of the rotor 103, which is connected to the rotor vanes 102 (102a, 102b, 102c, ...). The outer peripheral surface of the cylindrical part 102d is cylindrical and protrudes toward the inner peripheral surface of the threaded spacer 131, and is adjacent to the inner peripheral surface of the threaded spacer 131 with a predetermined gap therebetween. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blade 123 is guided by the thread groove 131a and sent to the base portion 129.

More specifically, the exhaust gas guided by the thread groove 131a is sent to an annular space 160 formed above the base portion 129, and is discharged to the outside through the exhaust port 133 while circulating around the annular space 160. This annular space 160 is an annular space partitioned by the cylindrical portion 102d of the rotating body (rotor) 103, the threaded spacer (stator portion) 131, the heater spacer 153, and the insulator wall (partition portion) 152.

Here, the heater spacer 153 is formed in a cylindrical shape and is interposed between the threaded spacer 131 and the insulator wall 152. The heater spacer 153 is made of a metal such as aluminum or stainless steel. The heater spacer 153 positions the threaded spacer 131 and the insulator wall 152 in the axial direction. A heater 195 is inserted into the heater spacer 153 as a heating means, and the heater 195 generates heat to heat the threaded spacer 131 via the heater spacer 153. The heater 195 also heats the exhaust gas flowing through the annular space 160. This suppresses the generation of deposits due to a drop in the temperature of the exhaust gas.

The insulator wall 152 is a disk-shaped member made of metal such as aluminum or stainless steel. The insulator wall 152 is disposed above the base portion 129 and below the threaded spacer 131, i.e., between the base portion 129 and the threaded spacer 131 in the axial direction of the turbo molecular pump 100, and a predetermined gap is provided between the insulator wall 152 and the base portion 129. This gap prevents heat from being transferred from the insulator wall 152 to the base portion 129. A heat transfer suppressing member 155 is attached to the inner peripheral surface of the insulator wall 152. This heat transfer suppressing member 155 is intended to suppress the transfer (thermal conduction and/or heat radiation) of heat transferred to the insulator wall 152 to the stator column 122 and the base portion 129, which will be described later. The configuration around the insulator wall 152 will be described in detail later.

The base portion 129 is a disk-shaped member that forms the base of the turbomolecular pump 100, and is generally made of a metal such as iron, aluminum, or stainless steel. The base portion 129 not only physically holds the turbomolecular pump 100, but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the rotor 102 and the fixed blades 123 act to draw exhaust gas from the chamber through the intake port 101. The rotation speed of the rotor 102 is usually 20,000 rpm to 90,000 rpm, and the peripheral speed at the tip of the rotor 102 reaches 200 m/s to 400 m/s. The exhaust gas drawn in from the intake port 101 passes between the rotor 102 and the fixed blades 123 and is transferred to the base part 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121, but this heat is transferred to the fixed blades 123 side by radiation or conduction by gas molecules of the exhaust gas.

The fixed blade spacers 125 are joined together at their outer periphery and transmit to the outside heat received by the fixed blades 123 from the rotor blades 102 and frictional heat generated when exhaust gas comes into contact with the fixed blades 123.

In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotor 103, and the thread groove 131a is engraved on the inner periphery of the threaded spacer 131. However, there are also cases where the opposite is true, that is, a thread groove is engraved on the outer periphery of the cylindrical portion 102d, and a spacer having a cylindrical inner periphery is disposed around it.

Depending on the application of the turbomolecular pump 100, the electrical equipment section, which is composed of the upper radial electromagnet 104, upper radial sensor 107, motor 121, lower radial electromagnet 105, lower radial sensor 108, axial electromagnets 106A and 106B, and axial sensor 109, may be covered with a stator column 122 and a predetermined pressure may be maintained inside the stator column 122 with purge gas to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section.

In this case, piping (not shown) is provided in the base portion 129, and purge gas is introduced through this piping. The introduced purge gas is sent to the exhaust port 133 through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102. As shown in FIG. 1, the stator column 122 is erected at the center position of the base portion 129. In addition, as will be described later, in this embodiment, the base portion 129 is provided with a water-cooled pipe 149 as a cooling means. By supplying cooling water to this water-cooled pipe 149, the base portion 129 and the stator column 122 are kept at a suitable temperature.

The turbomolecular pump 100 requires control based on the model identification and individually adjusted unique parameters (for example, various characteristics corresponding to the model). To store these control parameters, the turbomolecular pump 100 has an electronic circuit section 141 in its main body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown), for example near the center of the base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom cover 145.

In the semiconductor manufacturing process, some process gases introduced into the chamber have the property of becoming solid when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. If the pressure of the process gas becomes higher than a predetermined value or the temperature falls below a predetermined value while the process gas is being transferred from the intake port 101 to the exhaust port 133, the process gas becomes solid and adheres to and accumulates inside the turbomolecular pump 100.

For example, when SiCl4 is used as the process gas in an Al etching device, the vapor pressure curve shows that at low vacuum (760 torr to 10-2 torr) and low temperature (approximately 20°C), solid products (e.g. AlCl3) precipitate and deposit inside the turbomolecular pump 100. As a result, when process gas deposits accumulate inside the turbomolecular pump 100, the deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The aforementioned products are prone to solidification and adhesion in areas of high pressure near the exhaust port 133 and near the threaded spacer 131.

Therefore, in order to solve this problem, conventionally, a heater (not shown) or a circular water-cooled tube 149 is wrapped around the outer periphery of the base portion 129, etc., and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 129, and the heating of the heater and the cooling by the water-cooled tube 149 are controlled based on the signal from this temperature sensor to keep the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; TMS; Temperature Management System).

Next, regarding the turbomolecular pump 100 configured in this manner, we will explain the amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B. A circuit diagram of this amplifier circuit 150 is shown in Figure 2.

In FIG. 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to the positive pole 171a of the power supply 171 via the transistor 161, and the other end is connected to the negative pole 171b of the power supply 171 via the current detection circuit 181 and the transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

At this time, the transistor 161 has its diode cathode terminal 161a connected to the positive electrode 171a, and its anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has its diode cathode terminal 162a connected to the current detection circuit 181, and its anode terminal 162b connected to the negative electrode 171b.

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

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

Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) (not shown) of the control device 200, and this amplifier control circuit 191 is configured to switch the transistors 161 and 162 on and off.

The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Then, based on the result of this comparison, it determines the size of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control. As a result, gate drive signals 191a, 191b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of transistors 161, 162.

When the rotor 103 passes through a resonance point during accelerated operation or when a disturbance occurs during constant speed operation, it is necessary to control the position of the rotor 103 at high speed and with strong force. For this reason, a high voltage of, for example, about 50 V is used as the power supply 171 so that the current flowing through the electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between the positive pole 171a and the negative pole 171b of the power supply 171 to stabilize the power supply 171.

In this configuration, when both transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereafter referred to as electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

Furthermore, when one of the transistors 161, 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By passing a flywheel current through the amplifier circuit 150 in this manner, the hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Furthermore, by controlling the transistors 161, 162 in this manner, high-frequency noise such as 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 winding 151 can be detected.

In other words, when the detected current value is smaller than the current command value, both transistors 161 and 162 are turned on for a time period equivalent to pulse width time Tp1 only once during control cycle Ts (e.g., 100 μs) as shown in FIG. 3. Therefore, the electromagnet current iL during this period increases toward the current value iLmax (not shown) that can flow from positive pole 171a to negative pole 171b via transistors 161 and 162.

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

In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, during this period, a flywheel current is maintained in the amplifier circuit 150.

Next, the characteristic parts of the turbomolecular pump 100 according to the first embodiment will be described in detail. FIG. 5 is an enlarged view of the main part of the A part in FIG. 1. As shown in FIG. 5, the threaded spacer 131 and the insulator wall 152 are arranged with a gap in the axial direction, and a heater spacer 153 is interposed between them. The exhaust gas taken in from the intake port 101 passes between the thread groove 131a and the cylindrical part 102d as indicated by the arrow F in FIG. 5, and enters the annular space 160. The exhaust gas then flows through this annular space 160 and is discharged to the outside from the exhaust port 133.

The insulator wall 152 has a disk-shaped base 152a, a cylindrical portion 152b standing on the inner periphery of the base 152a, a locking portion 152c extending radially outward (to the right in FIG. 5) from the cylindrical portion 152b, and a step portion 152d.

Specific regions R are formed on the lower end surface of the cylindrical portion 102d of the rotor 103, the lower portion of the stator column 122, and the center of the base portion 129. These specific regions R are regions that face the insulator wall 152. A heat transfer suppression member 155 that is separate from the insulator wall 152 is attached to the region of the surface of the insulator wall 152 that faces the specific region R. In other words, the heat transfer suppression member 155 is detachably provided on the inner peripheral surface of the insulator wall 152.

The heat transfer suppression member 155 includes a cylindrical body portion 155b, an upper flange portion 155a extending radially outward from the upper end of the body portion 155b, and a lower flange portion 155c extending radially outward from the lower end of the body portion 155b. A small gap CL is formed as a seal structure between the upper surface of the upper flange portion 155a and the lower end surface of the cylindrical portion 102d. This gap CL prevents exhaust gas from the screw groove 131a from flowing into the stator column 122.

Here, the relationship between the radial length (width) a of the upper flange portion 155a and the radial length (width) c of the lower flange portion 155c is length a < length c. This is to effectively suppress the transfer of heat from the base portion 152a of the insulator wall 152 to the specific region R formed in the base portion 129. In addition, the length a is set to an appropriate length in consideration of the performance (sealing performance) of the above-mentioned seal structure and the load of the motor 121. In addition, the relationship between the axial length (height) b of the body portion 155b, the length a of the upper flange portion 155a, and the length c of the lower flange portion 155c is length a < length c < length b. This is to effectively suppress the transfer of heat from the cylindrical portion 152b of the insulator wall 152 to the specific region R of the stator column 122.

When the heat transfer suppression member 155 is attached to the inner peripheral surface of the insulator wall 152, the upper flange portion 155a of the heat transfer suppression member 155 is engaged with the engagement portion 152c of the insulator wall 52, and the lower flange portion 155c abuts against the step portion 152d. Here, the height of the step portion 152d is the same dimension as the thickness of the lower flange portion 155c, so that the surface of the lower flange portion 155c and the surface of the base portion 152a of the insulator wall 152 are flush with each other.

The heat transfer suppression member 155 is made of a material with a lower thermal conductivity than the insulator wall 152. For example, in this embodiment, the heat transfer suppression member 155 is made of stainless steel. By taking the above measures, the heat transfer suppression member 155 can suppress the transfer of heat stored in the insulator wall 152 toward the specific region R. Specifically, the temperature of the insulator wall 152 rises due to the heater 195 and exhaust gas, but since the heat transfer suppression member 155 has a lower thermal conductivity than the insulator wall 152, heat transfer from the heat transfer suppression member 155 toward the specific region R is suppressed.

The first embodiment configured in this way provides the following effects:

Since the heat transfer suppression member 155 is configured separately from the insulator wall 152, the design of the heat transfer suppression member 155 can be changed appropriately according to the conditions of the gas being handled without changing the design of the insulator wall 152, allowing it to be adapted to any usage environment. Therefore, this embodiment offers high design freedom and versatility. In addition, since only the heat transfer suppression member 155 needs to be made of a suitable material, there is no need to change the material of the insulator wall 152 itself. Therefore, this embodiment also contributes to cost reduction.

Because the heat transfer suppression member 155 is configured separately from the insulator wall 152, heat transfer to the heat transfer suppression member 155 is a form of heat transfer between solids, and heat transfer can be suppressed. In addition, because the heat transfer suppression member 155 is made of a material with low thermal conductivity, the temperature of the heat transfer suppression member 155 is less likely to rise. The heat transfer suppression member 155 suppresses the transfer of heat from the insulator wall 152 to the stator column 122, the cylindrical portion 102d of the rotor 103, and the base portion 129 (i.e., the specific region R). Therefore, it is possible to prevent the electrical components in the stator column 122 from breaking down due to heat. In addition, it is possible to suppress the rise in temperature of the water flowing through the water-cooled pipe 149 in the base portion 129.

In addition, since the heat transfer suppression member 155 is composed of the body portion 155b and the upper and lower flange portions 155a and 155c, the heat transfer suppression member 155 can be easily attached to the insulator wall 152 by simply engaging the upper flange portion 155a with the engaging portion 152c of the insulator wall 152 and abutting the lower flange portion 155c against the step portion 152d of the insulator wall 152. Furthermore, since the step portion 152d is configured so that the lower end surface of the heat transfer suppression member 155 and the lower end surface of the insulator wall 152 are flush with each other, the gap between the insulator wall 152 and the base portion 129 is uniform. Therefore, for example, when a purge gas is flowed, the flow path of the purge gas is not narrowed, so the flow of the purge gas is smooth.

Second Embodiment
Next, a turbomolecular pump 100-1 according to a second embodiment will be described. The same components as those in the first embodiment will be denoted by the same reference numerals and will not be described. Fig. 6 is a vertical cross-sectional view of a turbomolecular pump according to a second embodiment of the present invention, and Fig. 7 is an enlarged view of a main part of part B in Fig. 6.

The second embodiment is characterized in that it has a structure that further improves the sealing performance between the cylindrical portion 102d of the rotor 103 and the insulator wall 252 compared to the first embodiment. As shown in Figures 6 and 7, in the second embodiment, a recess 102e is provided on the lower end surface of the cylindrical portion 102d of the rotor 103, and the tip portions of the insulator wall 252 and the heat transfer suppression member 255 are inserted into this recess 102e with a small gap CL remaining.

As shown in FIG. 7, the insulator wall (partition) 252 has a disk-shaped base 252a, a cylindrical portion 252b standing on the inner periphery of the base 252a, and a step portion 252d.

Specific regions R are formed in the recess 102e formed in the lower end surface of the cylindrical portion 102d of the rotor 103, the lower portion of the stator column 122, and the center of the base portion 129. These specific regions R are regions that face the insulator wall 252. A heat transfer suppression member 255, which is separate from the insulator wall 252, is detachably attached to the insulator wall 252 in a region of the surface of the insulator wall 252 that faces the specific region R.

The heat transfer suppression member 255 has a cylindrical body portion 255b, a bent portion 255a that is bent in a hairpin shape from the upper end of the body portion 255b, and a lower flange portion 255c that extends radially outward from the lower end of the body portion 155b.

The gap d of the bent portion 255a is approximately equal to the thickness of the cylindrical portion 252b of the insulator wall 252. The relationship between the axial length (height) e of the body portion 255b and the length f of the lower flange portion 255c is length f < length e. This is to effectively suppress the transfer of heat from the cylindrical portion 252b of the insulator wall 252 to the specific region R of the stator column 122.

When the heat transfer suppression member 255 is attached to the inner peripheral surface of the insulator wall 252, the bent portion 255a of the heat transfer suppression member 255 is engaged so as to cover the tip of the cylindrical portion 252b of the insulator wall 252, and the lower flange portion 255c abuts against the step portion 252d. In this state, the bent portion 255a of the heat transfer suppression member 255 and the tip of the cylindrical portion 252b of the insulator wall 252 are inserted into the recess 102e. In addition, since the height of the step portion 252d is the same dimension as the thickness of the lower flange portion 255c, the surface of the lower flange portion 255c and the surface of the base portion 252a of the insulator wall 252 are flush with each other.

As in the first embodiment, the heat transfer suppression member 255 is made of a material having a lower thermal conductivity than the insulator wall 252. Furthermore, the surface of the heat transfer suppression member 255 is mirror-finished, and the emissivity is lower than that of the insulator wall 252.

The second embodiment configured in this manner can achieve the same effect as the first embodiment, such as the heat transfer suppression member 255 being able to suppress the heat stored in the insulator wall 252 from moving toward the specific region R. Furthermore, because the insulator wall 252 and a part (tip) of the heat transfer suppression member 255 are inserted into the recess 102e with a small gap CL remaining, there is also the advantage that exhaust gas can be prevented from flowing out of the annular space 160 into the gap between the insulator wall 252 and the stator column 122 (i.e., sealing performance is improved).

Third Embodiment
Next, a turbomolecular pump 100-2 according to a third embodiment will be described. The same components as those in the first and second embodiments will be denoted by the same reference numerals and will not be described. Fig. 8 is a vertical cross-sectional view of a turbomolecular pump according to a third embodiment of the present invention, and Fig. 9 is an enlarged view of a main part of part C in Fig. 8.

As shown in Figures 8 and 9, the third embodiment is characterized in that the threaded spacer and the heater spacer are integrated into one structure.

Specifically, as shown in FIG. 8, the insulator wall 152 is provided so as to abut against the lower end surface of the threaded spacer 331, and an annular space 160 through which exhaust gas flows is formed between the insulator wall 152 and the threaded spacer 331. A heater 195 is inserted into the threaded spacer 331. Even with this configuration, it is possible to achieve the same effects as the first embodiment. In addition, since the heater spacer 153 is not required, this configuration is superior to the first embodiment in that the number of parts is reduced.

The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention. All technical matters included in the technical ideas described in the claims are the subject of the present invention. The above-described embodiment shows a preferred example, but a person skilled in the art can realize various alternatives, modifications, variations, combinations, or improvements from the contents disclosed in this specification, and these are included in the technical scope described in the attached claims.

For example, stainless steel has been exemplified as the material of the heat transfer suppression member 155, 255, but the present invention is not limited to this. The heat transfer suppression member 155, 255 may be made of a material with a lower thermal conductivity than the insulator wall 152, 252. Furthermore, as a method of suppressing heat transfer, the heat transfer suppression member 155, 255 may be made of a material with a lower emissivity than the insulator wall 152, 252. In addition to selecting a material, as a method of lowering the emissivity, at least the surface of the heat transfer suppression member 155, 255 facing the specific region R may be mirror-finished, so that the emissivity of the surface is lower than that of the base material of the heat transfer suppression member 155, 255. Furthermore, the surface treatment of the heat transfer suppression member 155, 255 is not limited to mirror finishing. Any surface treatment with low emissivity may be used.

In addition, although the axial length of the heat transfer suppression member 155, 255 is equal to the height of the cylindrical portion 152b, 252b of the insulator wall 152, 252, the length of the heat transfer suppression member 155, 255 may be smaller than the cylindrical portion 152b, 252b.

In addition, although a cartridge-type heater 195 is shown as an example of the heating means, other types of heaters may also be used.

100, 100-1, 100-2 Turbo molecular pump (vacuum pump)
101: Intake port 102d: Cylindrical portion 102e: Recess 103: Rotor
122 stator column 127 outer cylinder 129 base portion (base)
131, 331 Threaded spacer (stator part)
131a, 331a Thread groove 133 Exhaust port 149 Cooling pipe (cooling means)
152, 252 Insulator wall (partition)
152a, 252a Base portion 152b, 252b Cylindrical portion 152c Locking portion 152d, 252d Step portion 153 Heater spacer 155, 255 Heat transfer suppressing member 155a Upper flange portion 155b, 255b Body portion 155c, 255c Lower flange portion 160 Annular space (flow path)
195 Heater (heating means)
255a Bending portion R Specific region

Claims (8)

With the base,
a stator column provided upright at a central position of the base;
a rotor rotatably supported by the stator column;
A stator portion disposed on an outer circumferential side of the rotor;
A heating means for heating the stator portion;
a partition wall portion disposed between the base and the stator portion and forming a flow path through which an exhaust gas flows together with the stator portion,
at least a portion of the partition wall has an opposing region that faces specific regions formed on the base, the stator column, and the rotor with a predetermined gap therebetween;
A vacuum pump characterized in that the opposing region is provided with a heat transfer suppressing member that suppresses heat transfer from the opposing region to the specific region without being in physical contact with the specific region. 2. The vacuum pump according to claim 1,
The vacuum pump according to claim 1, wherein the heat transfer suppressing member is made of a material having a lower thermal conductivity than the partition wall. 3. The vacuum pump according to claim 1,
The vacuum pump according to claim 1, wherein the heat transfer suppressing member is surface-treated so as to have a lower emissivity than the partition wall. The vacuum pump according to any one of claims 1 to 3,
A vacuum pump comprising a cooling means for cooling the base and the stator column. The vacuum pump according to any one of claims 1 to 4,
A vacuum pump, characterized in that the heat transfer suppression member comprises a cylindrical body portion and a flange portion extending radially outward from one end side of the body portion. 6. The vacuum pump according to claim 5,
A vacuum pump, wherein an axial length of the body portion is greater than a radial length of the flange portion. 7. The vacuum pump according to claim 5,
the partition wall has a step portion that comes into contact with the flange portion,
a partition wall portion and a flange portion, the partition wall portion being flush with each other when the flange portion and the partition wall are in contact with each other; A heat transfer suppressing member for a vacuum pump, the heat transfer suppressing member being used in a vacuum pump including a base, a stator column erected at a central position of the base, a rotor rotatably held relative to the stator column, a stator portion disposed on an outer periphery of the rotor, a heating means for heating the stator portion, and a partition portion disposed between the base and the stator portion and forming, together with the stator portion, a flow passage through which exhaust gas flows, the heat transfer suppressing member being attached to the partition portion as a separate body,
The heat transfer suppression member of a vacuum pump is characterized in that, when attached to the partition, the heat transfer suppression member suppresses the transfer of heat from the partition to the base, the stator column, and the rotor in a non-physical contact state.

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