JP2003254285A - Pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pump device which reduces costs of additional parts for temperature control such as a heater. <P>SOLUTION: The pump device is used to discharge process gas from, for example, a semiconductor manufacturing device, and journals a rotor on magnetic bearings. For reducing solidification and deposition of process gas in a pipeline of the pump device, bearing electromagnets of the magnetic bearings are heated to hold a high temperature of the pipeline. The bearing electromagnets are heated, for example, when a control current and a bias current are passed or a high frequency current is passed. Alternatively, a motor can be heated when the rotating speed of the motor is repeatedly increased and decreased, to elevate the temperature of the pipeline. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump device,
For example, it relates to a turbo molecular pump used for manufacturing a semiconductor.

[0002]

2. Description of the Related Art A semiconductor is manufactured in a chamber while a process gas is applied to a substrate. For evacuation of this chamber, a turbo molecular pump is widely used because of requirements such as evacuation capacity and degree of vacuum. Turbo molecular pump
It is used for exhausting process gas and the like in the chamber and for maintaining the inside of the chamber at a predetermined pressure.

There are various kinds of process gases used for manufacturing semiconductors, but depending on conditions such as temperature and pressure,
It may solidify and accumulate in the pipeline. Therefore, if the turbo molecular pump is operated for a certain period of time, deposits may be generated in the pipelines, the pipelines may be clogged, and the performance may be reduced, or the rotors and deposits may come into contact and adversely affect the pump operation. .

Therefore, in order to prevent the process gas from solidifying in the pipeline, it is widely practiced to install a heater around the pump to keep the pipeline at a high temperature. By controlling the temperature of the pump to a predetermined value using the heater, it is possible to reduce the solidification of the process gas in the pump.

[0005]

However, when the temperature of the turbo molecular pump is controlled by using the heater, additional parts such as a heater, a controller for controlling the heater, and a power cable are required, which causes a cost increase. It was

Therefore, an object of the present invention is to provide a pump device which can reduce the cost required for additional parts for temperature control such as a heater.

[0007]

In order to achieve the above-mentioned object, the present invention, in the invention described in claim 1, has an intake port formed on one end side and an exhaust port formed on the other end side. A casing, a base member that forms a base on the other end side of the casing, a cylindrical member fixed to the base member and accommodating a bearing and a motor, and rotatably accommodated in the cylindrical member by the bearing, A rotor shaft rotated by the motor; a rotor disposed on the rotor shaft; a stator disposed on the inner peripheral surface of the casing with a predetermined gap from the rotor; the rotor and the stator; And a heat generation control means for controlling the amount of heat generated in the cylindrical member. The pump according to claim 1, wherein the bearing is a magnetic bearing, and the heat generation control unit controls a bias current superimposed on a control current of the magnetic bearing. Provide a device. In the invention according to claim 3, the bearing is a magnetic bearing, and the heat generation control means controls a high-frequency current superposed on a control current of the magnetic bearing. Provide a device. The invention according to claim 4 is characterized in that the heat generation control means controls the heat generation amount of the motor by varying the rotation speed of the motor. 3 provides a pump device according to item 3. The invention according to claim 5 is characterized in that the cylindrical member, the base member, the rotor, and the stator are made of aluminum or an aluminum alloy. A pump device according to any one of the claims is provided. The invention according to claim 6 is characterized in that the reinforcing member disposed around the motor or the exterior member of the bearing is made of aluminum or an aluminum alloy. A pump device is provided. The invention according to claim 7 is characterized in that at least a part of the surfaces of the stator and the rotor facing each other is coated with a coating for increasing the efficiency of heat radiation. A pump device according to any one of the preceding claims is provided. Claim 8
In the invention described in claim 1, at least a part of the outer peripheral surface of the cylindrical member faces the inner peripheral surface of the rotor with a predetermined gap, and at least a part of the facing surfaces of the cylindrical member and the rotor. The pump device according to any one of claims 1 to 7, characterized in that the pump device is coated with a coating for increasing heat radiation efficiency. In the invention according to claim 9, a cooling control means for controlling the cooling means in relation to a cooling means formed in the pump device and a temperature detected by a temperature detecting means installed at a predetermined position of the pump device. The pump device according to any one of claims 1 to 8 is further provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below. (1) Outline of Embodiment As shown in FIG. 2, the turbo molecular pump 1 according to the present embodiment includes a rotor shaft 11 by means of magnetic bearing portions 8, 12, 20.
Is magnetically levitated and is pivotally supported. Of these, the magnetic bearings 8, 12, and 20 have temperature sensors 31, 32, and 32, respectively.
33 attached, temperature controller 52 (FIG. 1)
The temperature of the bearing electromagnets of the magnetic bearing portions 8, 12, 20 is monitored by.

The current supplied to these bearing electromagnets includes
In addition to the displacement control current for controlling the displacement of the rotor shaft 11, a DC bias current is superimposed. This bias current causes the bearing electromagnet to generate heat.

The temperature controller 52 (FIG. 1) uses the detection signals from the temperature sensors 31, 32 and 33 to maintain the temperature of the electromagnets of the magnetic bearing portions 8, 12 and 20 within a preset predetermined range. Set the value of the bias current to. Then, the control device 51 supplies the bias current set by the temperature controller to the electromagnets of the magnetic bearing portions 8, 12, 20 in addition to the displacement control current. That is, the bias current is feedback-controlled by the detection signals of the temperature sensors 31, 32 and 33.

Since the bearing electromagnet is heated by the bias current, the temperature of the conduit of the turbo molecular pump 1 rises,
It is possible to reduce the solidification of the process gas in the pump.

(2) Details of Embodiment FIG. 1 is a diagram showing a turbo molecular pump 1 of this embodiment installed in a chamber 60. Chamber 60
Is a container with airtightness, and various operations for semiconductor manufacturing such as dry etching and lamination can be performed inside. Although not shown, the chamber 60 is provided with a process gas release port used for manufacturing a semiconductor, and the process gas released from the release port can create a predetermined atmosphere in the chamber 60.

The turbo molecular pump 1 is installed in a suspended state on the lower end surface of the chamber 60 via a conductance valve 55. Conductance valve 55
Is, for example, a valve including a valve body configured by a butterfly valve. In the butterfly valve, a disc-shaped valve body 56 having a diameter equal to the inner diameter of the flow path is placed in a cylindrical valve box, and the valve body 56 is rotated about a diameter axis to open and close. The cross-sectional area of the flow path can be adjusted by rotating the valve body 56 from the outside of the conductance valve 55. Further, in FIG. 1, the valve body 56 arranged inside the conductance valve 55 is shown by a dotted line.

The conductance valve 55 is a valve that adjusts the conductance (ease of gas flow), and is installed to adjust the degree to which the turbo molecular pump 1 sucks the exhaust gas. In this way, the pressure inside the chamber can be adjusted by opening and closing the conductance valve 55 that adjusts the extent to which the turbo molecular pump 1 sucks the exhaust gas from the vacuum device.

The turbo molecular pump 1 is a pump for exhausting the gas in the chamber 60 to the auxiliary pump side by rotating a rotor portion, which is supported by a magnetic bearing portion, at a high speed. The magnetic bearing unit is a device for magnetically levitating the rotor shaft and holding it at a predetermined position by the attraction force of a plurality of electromagnets (hereinafter referred to as bearing electromagnets) installed around the rotor shaft and at the bottom.

The control device 51 is a device for controlling the magnetic bearing portion and the motor portion provided on the rotor shaft. With respect to the magnetic bearing portion, the displacement of the rotor shaft is detected by a sensor, and a displacement control current is supplied to the bearing electromagnet so that the rotor shaft is held at a predetermined position to adjust the magnetic force. With respect to the motor unit, the number of rotations of the rotor shaft is detected by a sensor, and a current supplied to a stator coil (hereinafter simply referred to as a stator coil) forming the motor unit is adjusted.

Further, the control device 51 can supply a displacement control current to the magnetic bearing portion as well as a DC bias current by a control signal (hereinafter referred to as a bias signal) from the temperature controller 52. This bias current causes the bearing electromagnet to generate heat, which heats the conduit of the turbo molecular pump 1.

The temperature controller 52 detects the temperature of these parts by a detection signal from a temperature sensor attached to the bearing electromagnet. Then, the current value is set so that the detected temperature is maintained within a predetermined range set in advance, and this is output to the control device 51. The control device 51 is
A bias current according to this current value is supplied to the magnetic bearing portion.

FIG. 2 is a view showing a sectional view in the axial direction of the turbo molecular pump 1 of the present embodiment. In this embodiment, a turbo molecular pump including a turbo molecular pump unit and a thread groove type pump unit is used as an example of the molecular pump.

The casing 16 forming the outer casing of the turbo molecular pump 1 has a cylindrical shape, and the rotor shaft 11 is installed at the center thereof. The casing 16 forms an exterior body of the turbo molecular pump 1 together with a base 27 described later. A stator column 46, which is a cylindrical member having a substantially cylindrical shape, is formed at the center of the base 27 on the intake port 6 side. The magnetic bearing portions 8 and 12 for supporting the rotor shaft 11 and the motor portion 10 for rotating the rotor shaft 11 are housed on the inner peripheral surface of the stator column 46.

The magnetic bearings 8 and 12 are respectively the rotor shaft 1
It is provided in the upper part and the lower part of 1 in the axial direction. A magnetic bearing portion 20 is provided on the bottom of the rotor shaft 11. The rotor shaft 11 is supported by the magnetic bearing portions 8 and 12 in the radial direction (radial direction of the rotor shaft 11) without contact, and the magnetic bearing portion 20 supports the thrust direction (rotor shaft 1).
1 is supported in a non-contact manner. These magnetic bearing portions constitute a so-called five-axis control type magnetic bearing, and the rotor shaft 11 is adapted to rotate around its axis.

In the magnetic bearing portion 8, for example, four bearing electromagnets are arranged around the rotor shaft 11 so as to face each other at 90 ° intervals. An electromagnet target 48 is formed on a portion of the rotor shaft 11 that constitutes the magnetic bearing portion 8.
The electromagnet target 48 is formed of a laminated steel plate in which a large number of steel plates such as silicon steel having an insulating film formed on the surface thereof are laminated. This is installed in order to suppress the generation of eddy currents on the rotor shaft 11 due to the magnetic field generated in the magnetic bearing portion 8. When eddy current is generated in the rotor shaft 11, the rotor shaft 11 generates heat and eddy current loss is generated, resulting in a decrease in efficiency.
This can be prevented by configuring 8 with a laminated steel plate. In the magnetic bearing portion 8, the electromagnet target 48 is attracted by the magnetic force of the electromagnet, and the rotor shaft 11 is magnetically levitated in the radial direction. A temperature sensor 31 is attached to the bearing electromagnet of the magnetic bearing unit 8 so that the temperature of the bearing electromagnet can be detected.

A radial sensor 9 is formed near the magnetic bearing portion 8. The radial sensor 9 is composed of, for example, a coil arranged around the rotor and a radial sensor target 47 formed on the rotor shaft 11. The coil forms a part of the oscillation circuit of the control device 51, and the amplitude of the signal changes depending on the distance between the coil and the radial sensor target 47, so that the displacement of the rotor shaft 11 is detected.

The radial sensor target 47, like the electromagnet target 48, is made of laminated steel plates. The control device 51 based on the signal from the radial sensor 9
Feedback-controls the magnetic force generated by the magnetic bearing portion 8. Other sensors for detecting the displacement of the rotor shaft 11 include a capacitance type sensor and an optical type sensor.

The structures and operations of the magnetic bearing portion 12 and the radial sensor 13 are the same as those of the magnetic bearing portion 8 and the radial sensor 9, respectively, and therefore description thereof will be omitted. The magnetic bearing 12
A temperature sensor 32 is attached to the bearing electromagnet of
The temperature of the bearing electromagnet can be detected.

The magnetic bearing portion 20 provided at the lower end of the rotor shaft 11 includes a disk-shaped metal disk 26 and a bearing electromagnet 1.
4, 15 and the thrust sensor 17. The metal disk 26 is made of a high-permeability material such as iron, and is fixed vertically to the rotor shaft 11 at the center thereof. The bearing electromagnet 14 is provided on the metal disk 26.
Is installed, and the bearing electromagnet 15 is installed below.
The bearing electromagnet 14 attracts the metal disk 26 upward by magnetic force, and the bearing electromagnet 15 attracts the metal disk 26 downward. A temperature sensor 33 is attached to the bearing electromagnet 15 so that the temperature of the bearing electromagnet 15 can be detected.

The thrust sensor 17 is composed of, for example, a coil, like the radial sensors 9 and 13, and detects the displacement of the rotor shaft 11 in the thrust direction and sends it to the control device 51. The control device 51 can detect the displacement of the rotor shaft 11 in the thrust direction based on the signal received from the radial sensor 13.

When the rotor shaft 11 moves in one of the thrust directions and is displaced from a predetermined position, the controller 51 adjusts the exciting currents of the bearing electromagnets 14 and 15 so as to correct this displacement, and the rotor shaft 11 is moved. It operates so as to return it to a predetermined position. By this feedback control, the control device 51 can magnetically levitate the rotor shaft 11 at a predetermined position in the thrust direction and hold it. As described above, since the rotor shaft 11 is held in the radial direction by the magnetic bearing portions 8 and 12 and in the thrust direction by the magnetic bearing portion 20, the rotor shaft 11 has a degree of freedom of rotation about the axis. Supported.

A motor portion 10 is provided in the middle of the magnetic bearing portions 8 and 12 of the rotor shaft 11. In this embodiment,
As an example, it is assumed that the motor unit 10 is composed of a DC brushless motor. A permanent magnet is fixed around the portion of the rotor shaft 11 that constitutes the motor unit 10. This permanent magnet is fixed, for example, so that the N pole and the S pole are arranged around the rotor shaft 11 every 180 °. Around the permanent magnet, for example, six electromagnets are arranged at 60 ° through a predetermined clearance from the rotor shaft 11.
They are arranged so as to be symmetrical and opposed to the axis of the rotor shaft 11.

On the other hand, the turbo molecular pump 1 has a rotor shaft 1
A sensor (not shown) for detecting the number of rotations and the rotation angle (phase) of 1 is provided, which allows the control device 51 to detect the position of the magnetic pole of the permanent magnet fixed to the rotor shaft 11. ing. The control device 51 sequentially switches the currents of the electromagnets of the motor unit 10 according to the detected magnetic pole positions to generate a rotating magnetic field around the permanent magnets of the rotor shaft 11. The permanent magnet fixed to the rotor shaft 11 follows this rotating magnetic field, and the rotor shaft 11 rotates accordingly. On the outer peripheral surface of the motor unit 10, a collar 4 which is a cylindrical member made of stainless steel for protecting the motor unit 10 is provided.
9 is provided. The collar 49 is a reinforcing member for protecting the motor unit 10.

A rotor 24 is attached to the upper end of the rotor shaft 11 by a plurality of bolts 25. In the present embodiment, as an example, the intake port 6 starts from about the middle of the rotor 24.
The side, that is, the approximately upper half portion in the drawing is a turbo molecular pump portion composed of the rotor blades 21, the stator blades 22 and the like, and the approximately lower half portion in the drawing is composed of the spacer 5 which is a spacer with a screw. It has a thread groove type pump section. The structure of the turbo molecular pump is not limited to this. For example, from the intake port 6 side to the exhaust port 1
It may be configured by a thread groove type pump up to the 9 side.

In the turbo molecular pump section, the rotor 2
In No. 4, rotor blades 21 made of aluminum or aluminum alloy are inclined from the plane perpendicular to the axis of the rotor shaft 11 by a predetermined angle, and are mounted radially from the rotor 24 in a plurality of stages. The rotor blade 21 is the rotor 24
The rotor shaft 11 and the rotor shaft 11 rotate at high speed. On the intake port side of the casing 16, a stator blade 22 made of aluminum, an aluminum alloy, or the like is inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 11, and the rotor blade 21 is directed inward of the casing 16. The stairs are arranged alternately.

The spacer 23 is a ring-shaped member and is made of a metal such as aluminum, iron or stainless steel. The spacers 23 are arranged between the stages formed by the stator blades 22 and hold the stator blades 22 at predetermined positions.

When the rotor 24 is driven by the motor unit 10 and rotates with the rotor shaft 11, the exhaust gas is sucked from the intake port 6 by the action of the rotor blade 21 and the stator blade 22. The exhaust gas sucked from the intake port 6 passes between the rotor blade 21 and the stator blade 22, and is sent to the thread groove pump unit.

The thread groove type pump portion is composed of a rotor lower portion 29, a spacer 5 and the like. In this embodiment,
The thread groove is formed in the spacer 5. Lower rotor 29
Is formed of a portion having a cylindrical outer peripheral surface formed in a substantially lower half portion of the rotor 24, and the outer peripheral surface has the spacer 5
Overhangs to the area close to the inner surface of the. The stator of the screw groove type pump unit is configured by the spacer 5. The spacer 5 is a cylindrical member made of a metal such as aluminum, stainless steel, or iron, and has a plurality of spiral thread grooves 7 formed on its inner peripheral surface.

The spiral direction of the thread groove 7 is the direction in which the molecules of the exhaust gas are transferred to the exhaust port 19 when the molecules of the exhaust gas move in the rotation direction of the rotor 24. When the rotor 24 is driven by the motor unit 10 to rotate, the exhaust gas sent from the turbo molecular pump unit is guided to the screw groove 7 and transferred to the exhaust port 19. The gas pressure inside the turbo-molecular pump 1 varies from the intake port 6 to the exhaust port 19
The turbo molecular pump 1
The intake port 6 side of is composed of a turbo molecular pump unit, and the exhaust port 1
A high compression ratio can be realized by configuring 9 as the thread groove pump portion.

In the present embodiment, the threaded spacer having the thread groove 7 is arranged on the stator side, and the outer peripheral surface of the rotor lower portion 29 has a cylindrical shape, but conversely, the outer peripheral surface of the rotor is screwed. A turbo molecular pump having a groove may be used.

The base 27 is a disk-shaped member that constitutes the base of the turbo molecular pump 1, and is made of metal such as stainless steel, aluminum and iron. The casing 16 is joined to the upper end of the outer edge of the base 27,
The spacer 5 is installed inside thereof. In the center,
A mechanism for holding the rotor shaft 11 such as the magnetic bearings 8, 12, 20 and the motor unit 10 is installed.

A water cooling pipe 18 for circulating cooling water is attached to a lower portion of the base 27, and the water cooling pipe 18 and the base 27 are attached.
During this period, heat exchange is efficiently performed. The water cooling pipe 18 constitutes a cooling means. The heat transferred to the base 27 can be efficiently released to the outside of the turbo molecular pump 1 by the cooling water circulating in the water cooling pipe 18, so that the turbo molecular pump 1 is overheated and becomes higher than the allowable temperature. Can be prevented.

The water cooling pipe 18 constitutes a water cooling system together with a water supply pump (not shown) and a heat exchanger (not shown). The cooling water in the water cooling pipe 18 circulates in the water cooling system by the action of the water pump. Then, the heat obtained by the heat exchange of the cooling water with the base 27 is released by the heat exchanger to the outside of the water cooling system such as the atmosphere. As a result, the cooling water is cooled and sent again to the turbo molecular pump 1 by the water supply pump.

FIG. 3 is a schematic diagram for explaining the bearing control system 40 and shows the magnetic bearing portion 8 as viewed in the axial direction. The bearing control system 40 is a system that controls the current supplied to the bearing electromagnets 36 and 37 that form the magnetic bearing unit 8. This current includes a displacement control current for controlling the position of the rotor shaft 11 and a bias current for causing the bearing electromagnets 36 and 37 to generate heat. The bearing electromagnets 36 and 37 are arranged vertically with respect to the rotor shaft 11 toward the paper surface.
On the other hand, there are bearing electromagnets arranged on the left and right sides toward the paper surface, which are omitted for simplification of description.

The bearing control system 40 includes the temperature controller 5
2, magnetic bearing control circuit 43, displacement detection circuit 44, power amplifier 41, power amplifier 42, bearing electromagnets 36, 3
7, a radial sensor 9, a temperature sensor 31, a rotor shaft 11, and the like. Of these constituent elements, the magnetic bearing control circuit 43, the displacement detection circuit 44, the power amplifier 41, and the power amplifier 42 are included in the control device 51.

The temperature sensor 31 detects the temperature of the bearing electromagnet 37 and sends a temperature detection signal to the temperature controller 52. The temperature controller 52 calculates the temperature of the bearing electromagnet 37 from the temperature detection signal from the temperature sensor 31.
Then, it is determined whether or not the calculated temperature is within a preset temperature range (for example, 70 [° C] to 85 [° C]), and if the calculated temperature is below the lower limit of the preset temperature range, the bias current Is output to the magnetic bearing control circuit 43 so as to increase by a predetermined amount. On the other hand, when the calculated temperature exceeds the upper limit of the set temperature range, the bias signal is output so as to reduce the bias current by a predetermined amount. Output to the magnetic bearing control circuit 43.

The displacement detection circuit 44 receives the displacement signal from the radial sensor 9 and calculates the displacement amount of the rotor shaft 11,
The calculated displacement amount is output to the magnetic bearing control circuit 43. The magnetic bearing control circuit 43 inputs the bias signal from the temperature controller 52 and the displacement signal from the displacement detection circuit 44, and calculates the amount of current to be output to the bearing electromagnets 36 and 37 for each bearing electromagnet 36 and 37. . Then, a current signal indicating the calculated current amount is output to the power amplifiers 41 and 42.

In the present embodiment, the bearing electromagnet 3
The bias currents supplied to 6 and 37 have the same current value. This is because the bearing electromagnets 36 and 37 face each other. Therefore, if the bias current value is the same, the magnetic field generated in the bearing electromagnets 36 and 37 by the bias current is the rotor shaft 11.
This is because the magnetic force exerted on the elements cancels each other out. As a result, the influence of the bias current on the control of the displacement of the rotor shaft 11 can be reduced.

The magnetic bearing control circuit 43 sets the displacement control current by the displacement signal, sets the bias current by the bias signal, and outputs the current amount obtained by superposing the displacement control current and the bias current as a current signal. The displacement control current is
It is a current for correcting the displacement of the rotor shaft 11 and generating a magnetic field in the bearing electromagnets 36, 37 for returning the rotor shaft 11 to a predetermined position.

The power amplifiers 41 and 42 generate a predetermined current according to the current signal input from the magnetic bearing control circuit 43.
It supplies to the bearing electromagnet 36 and the bearing electromagnet 37, respectively.
The current supplied to the bearing electromagnets 36 and 37 is a combination of the displacement control current and the bias current. Then, the rotor shaft 11 is held at a predetermined position by the magnetic field generated by the displacement control current, and the bearing electromagnets 36, 37 are heated by the bias current.

In this way, the bias current is feedback-controlled by the detection signal of the temperature sensor 31, and the temperature of the bearing electromagnet 37 is maintained within a certain range. Like the bearing electromagnet 37, the temperature of the bearing electromagnet 36 is also kept within a certain range. Then, the heat generated by the bearing electromagnets 36 and 37 raises the temperature inside the turbo molecular pump 1 and can reduce the solidification of the process gas in the exhaust passage. As described above, the control device 51 constitutes the heat generation control means together with the temperature controller 52.

Although not shown, the rotor shaft 1 faces toward the paper surface.
The temperature of the bearing electromagnets arranged on the left and right of 1 is also controlled in the same manner. Further, the temperature of the magnetic bearing electromagnet forming the magnetic bearing portion 12 is similarly controlled. Further, in the present embodiment, no bias current is supplied to the bearing electromagnets 14 and 15 that form the magnetic bearing portion 20, but the bearing electromagnets 14 and 1 do not.
A temperature sensor may be installed at 5 to control the temperature in the same manner.

In FIG. 4, the power amplifier 41 has the bearing electromagnet 3
FIG. 6 is a diagram showing an example of a current 58 supplied to No. 6 in which the vertical axis represents current value and the horizontal axis represents time. The current 58 output from the power amplifier 41 to the bearing electromagnet 36 is a combination of a bias current for heating the bearing electromagnet 36 and a displacement current for controlling the displacement of the rotor shaft 11.

In FIG. 4, the DC component ΔI of the current 58 is
Is the bias current, and the AC component is the displacement current. In addition, in the present embodiment, together with the bearing electromagnet 36,
The bias current ΔI is also supplied to the bearing electromagnets 37 forming the magnetic bearing portion 8 and the bearing electromagnets (not shown) arranged on the left and right of the rotor shaft 11 toward the plane of the drawing in FIG. The value of the bias current ΔI may be changed for each bearing electromagnet, or may be changed by the displacement of the rotor shaft 11.

FIG. 5 is a flow chart for explaining the control procedure regarding the bias current in the operation performed by the bearing control system 40. First, the temperature controller 52 uses the temperature detection signal from the temperature sensor 31 to detect the bearing electromagnet 3
The temperature of 7 is measured (step 5). Next, the temperature controller 52 determines whether the measured temperature is lower than the lower limit of the preset temperature range (step 10).

When the measured temperature is lower than the lower limit of the preset temperature range (step 10; Y), the temperature controller 52 increases the bias current by a preset amount (for example, 20%). A bias signal is generated and output to the magnetic bearing control circuit 43 (step 15).
When the measured temperature is equal to or higher than the lower limit of the preset temperature range (step 10; N), the temperature controller 5
In step 2, it is determined whether the measured temperature is higher than the upper limit of the preset temperature range (step 20).

When the measured temperature is higher than the upper limit of the preset temperature range (step 20; Y), the temperature controller 52 reduces the bias current by a preset amount (for example, 20%). To generate a bias signal and output it to the magnetic bearing control circuit 43 (step 2
5). When the measured temperature is less than or equal to the upper limit of the preset temperature range (step 20; N), a bias signal for maintaining the current bias current is generated and output to the magnetic bearing control circuit 43 (step 30). .

Next, the magnetic bearing control circuit 43 sets a bias current from the bias signal input from the temperature controller 52, and outputs this to the power amplifier 41 together with a signal for setting the displacement control current. The power amplifier 41 outputs a predetermined bias current based on the control signal input from the magnetic bearing control circuit 43 (step 35).

The above procedure is followed by a specified time interval (for example, 1
Bearing electromagnets 36, 37
The temperature of can be maintained in a certain range. The above procedure has been described with respect to the case where the bias current is supplied to the bearing electromagnets 36 and 37. Bias current is supplied to control the temperature.

In the present embodiment described above, the temperature of the duct in the pump can be raised by supplying a bias current to the magnetic bearing portions 8 and 12 to generate heat. By controlling the amount of heat generated by increasing / decreasing the bias current of the magnetic bearing, it is possible to keep the temperature of the pipeline of the pump, thereby reducing the solidification of the process gas in the pipeline.

Since the turbo molecular pump 1 generates heat using a portion (magnetic bearing portion) originally provided for exhibiting the pump function, it is not necessary to attach accessory parts such as winding a heater to the turbo molecular pump 1. Therefore, the manufacturing cost can be reduced.

In the present embodiment, a bias current is supplied to the magnetic bearing portion to generate heat in this portion.
It is also possible to generate heat by the following two methods. (1) A high frequency wave having a predetermined frequency or higher is superimposed on the displacement control current. In this case, the frequency is the rotor part (rotor shaft 1
1 and the rotor 24) has a natural frequency (for example, 1 [kHz]). In this way, if the frequency is set above the natural frequency of the rotor,
The displacement of the rotor cannot follow the component of the magnetic field generated by the bearing electromagnet, which is caused by the high frequency. Therefore, the high frequency does not affect the displacement of the rotor portion, and the high frequency current causes the bearing electromagnet to generate heat.

(2) The number of rotations of the rotor is increased or decreased within a fixed range. Generally, when accelerating and decelerating the rotor part, a large current flows through the stator coil. On the other hand, during steady operation, the amount of current flowing through the stator coil is small. Therefore, by alternately accelerating and decelerating the rotor portion within a range that does not affect the exhaust of the gas, the motor portion 10 generates heat and the temperature of the pipeline in the pump can be raised.
In this case, when temperature control is performed by this method, a temperature sensor is attached to the motor unit 10, and while monitoring the temperature, if it is desired to raise the temperature of the motor unit 10, the acceleration / deceleration of the rotor unit is repeated to When it is desired to lower the temperature of the section 10, the rotation speed of the rotor section is kept constant.

FIG. 6 shows the motor unit 1 according to the method (2).
It is a figure showing an example of change of the number of rotations of a motor when controlling the temperature of 0. The vertical axis represents the rotation speed of the rotor shaft 11,
The horizontal axis represents time. When the motor unit 10 is caused to generate heat, the acceleration / deceleration of the motor rotation speed is repeated as shown in sections 61 and 63. On the other hand, when it is desired to cool the temperature of the motor unit 10, normal operation is performed while keeping the rotation of the motor unit 10 constant, as shown in the section 62. Motor part 1
The heat generation amount per unit time of 0 can be controlled by, for example, increasing the frequency of acceleration / deceleration of the motor rotation speed or widening the difference between the upper limit of the rotation speed and the acceleration / deceleration value. .

The system configuration for operating the turbo molecular pump 1 will be described with reference to FIG. Figure 1
In, the temperature controller 52 monitors the temperature of the motor unit 10 using a temperature sensor attached to the motor unit 10. Then, it is judged whether the monitored temperature is higher than the upper limit of the predetermined range or smaller than the upper limit, and the judgment result is sent to the control device 51. The control device 51 can operate the motor unit 10 in a heating mode in which the motor rotation speed is repeatedly increased and decreased (varied) and in a cooling mode in which the motor rotation speed is constant. The control unit 51
Depending on the judgment result of the temperature controller 52, the motor unit 10
If the temperature is higher than the upper limit of the predetermined range, the cooling mode is operated, and if it is lower than the lower limit, the heating mode is operated.

The above methods may be used in combination. For example, it is possible to superimpose a bias current or a high-frequency current on the bearing electromagnet and heat the motor section by the above method (2).

In addition to controlling the amount of heat generated in the magnetic bearings 8, 12, 20 and controlling the flow rate and temperature of the cooling water supplied to the water cooling pipe 18, the turbo molecular pump 1 can be more effectively operated.
Temperature control can be performed. In this case, for example, the temperature detecting means constituted by a thermocouple or the like is used as the stator column 4
6, the spacer 5, the base 27, etc., and the temperature of these is monitored. On the other hand, if a cooling control means for controlling the flow rate of the cooling water according to the detected temperature is provided and the detected temperature exceeds a predetermined set temperature, the flow rate of the cooling water is increased and falls below the predetermined temperature range. Reduces or stops the flow rate of the cooling water. In this way, turbo molecular pump 1
If you want to raise the temperature of the
By stopping, the energy consumption required for heating can be saved. The installation position of the water cooling unit 18 is not limited to the bottom portion of the base 27, and may be provided on the outer periphery of the base 27 or the casing 16.

(Modification of Embodiment) In the above-described embodiment, the mechanism for generating heat inside the turbo-molecular pump 1 has been described. However, in this modification, the generated heat is transferred to a conduit in the pump. I will explain the mechanism for prompt communication.

In this modification, the magnetic bearing portions 8, 12, 20 are used.
The following three methods have been adopted so that the heat generated in such cases can be efficiently transferred to the pipeline. (1) A member of a portion corresponding to a pipe line in the turbo molecular pump 1 is made of a material having high thermal conductivity. More specifically, the case, the collar 49, etc. for housing the magnetic bearing portions 8, 12, 20 have, for example, aluminum, an aluminum alloy, or a material having a thermal conductivity equal to or higher than that of the aluminum alloy (copper, silver, etc.). ). The case is an exterior member that constitutes an exterior body of the magnetic bearing portions 8, 12, 20 and is housed inside the stator column 43 together with the magnetic bearing body. Further, the rotor 24 is also formed of a member having a high thermal conductivity so that the heat generated in the magnetic bearing portions 8, 12, 20 can be quickly transmitted to the pipeline. At the same time, the stator column 46, the spacer 5, the base portion 27,
When the rotor 24 is made of aluminum or aluminum alloy, heat transfer can be improved.

(2) At least a part of the outer peripheral surface of the stator column 46, the inner peripheral surface of the rotor 24, the rotor blade 21, the rotor lower portion 29, and the opposing surface thereof is coated. The outer peripheral surface of the stator column 46, the inner peripheral surface of the rotor 24, the rotor blades 21 and the rotor lower portion 29 are usually plated with nickel or the like. These platings have high light reflectance, and heat from the surface is difficult to radiate. Therefore, the outer peripheral surface of the stator column 46, the inner peripheral surface of the rotor 24, the rotor blade 2
First, by coating at least a part of the surface of the rotor lower portion 29 and the facing surface thereof with a substance that easily radiates heat, it becomes possible to efficiently transfer heat by radiation.

The following types of coating can be considered, for example. Mix carbon, black ceramics, etc. with fluorine resin and paint. Perform chemical conversion treatment such as chromate treatment. Anodize to produce black alumite.

It is necessary to select a coating method that is less likely to corrode the portion that directly contacts the process gas. However, since the outer peripheral surface of the stator column 46 and the inner peripheral surface of the rotor 24 do not directly contact the process gas, there is concern about corrosion. However, any coating method may be adopted. Also,
You may coat only the part which does not touch a process gas directly.

As described above, according to this modification, the heat conduction inside the turbo molecular pump 1 can be improved and the temperature can be effectively controlled. Further, the temperature of the rotor 24 increased as a result of the temperature control of the magnetic bearing portions 8, 12, 20 can be effectively transmitted to the stator side.

Although one embodiment and one modification of the present invention have been described above, the present invention is not limited to these and various modifications can be made within the scope of the claims. .

[0072]

According to the present invention, the cost required for additional parts for temperature control such as a heater can be reduced.

[Brief description of drawings]

FIG. 1 is a view showing a turbo molecular pump installed in a chamber.

FIG. 2 is a cross-sectional view in the axial direction of the turbo molecular pump according to the present embodiment.

FIG. 3 is a schematic diagram for explaining a bias current control system.

FIG. 4 is one of the currents that the power amplifier supplies to the bearing electromagnet.
It is the figure which showed the example.

FIG. 5 is a flowchart for explaining a bias current control procedure.

FIG. 6 is a diagram showing an example of changes in the motor rotation speed when the temperature of the motor unit is controlled.

[Explanation of symbols]

1 Turbo molecular pump 5 spacers 6 intake 7 screw groove 8 Magnetic bearing 9 Radial sensor 10 Motor part 11 rotor shaft 12 Magnetic bearing 13 Radial sensor 14 Bearing electromagnet 15 Bearing electromagnet 16 casing 17 Thrust sensor 18 Water cooling tube 19 exhaust port 20 Magnetic bearing 21 rotor blades 22 Stator blade 23 Spacer 24 rotor 25 volts 26 metal discs 27 base 28 coils 29 Lower rotor 36 bearing electromagnet 37 Bearing electromagnet 40 Bearing control system 41 Power Amplifier 42 power amplifier 43 Magnetic bearing control circuit 44 Displacement detection circuit 46 Stator column 47 Radial sensor target 48 Electromagnetic Target 49 colors 51 control device 52 Temperature controller 55 Conductance valve 56 valve body 60 chambers

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F04B 49/06 331 F04B 49/06 331Z F04D 27/00 F04D 27/00 K 29/00 29/00 B 29 / 02 29/02 29/04 29/04 M P 29/54 29/54 F F 29/58 29/58 L M R S S F Term (reference) 3H021 AA02 AA08 BA01 BA11 BA20 CA06 CA07 DA00 DA03 EA07 3H022 AA03 BA01 BA04 BA06 BA07 CA16 CA48 CA50 CA51 CA55 CA56 DA01 DA04 DA09 DA12 DA13 DA14 3H031 DA01 DA02 DA07 EA01 EA02 EA03 EA12 EA15 FA01 FA13 FA31 FA34 FA35 3H034 AA01 AA02 AA03 AA12 DD02 DD15 DD24 DD02 DD15 DD03 DD02 CC15 CC03 CC06 CC07 CC07 CC06 CC06 CC06 CC07 CC06 CC06 CC24 CC07 3H045 AA06 AA09 AA13 AA25 AA26 AA31 BA01 BA31 CA19 DA00 DA05 EA34

Claims (9)

[Claims] 1. A casing having an intake port formed on one end side and an exhaust port formed on the other end side; a base member forming a base on the other end side of the casing; and fixed to the base member. A cylindrical member accommodating a bearing and a motor, a rotor shaft rotatably accommodated in the cylindrical member by the bearing and rotated by the motor, a rotor disposed on the rotor shaft, the rotor and a predetermined rotor. A stator disposed on the inner peripheral surface of the casing with a gap therebetween, a gas transfer unit formed in the gap between the rotor and the stator, and a heat generation control unit controlling the amount of heat generated in the cylindrical member. And a pump device. 2. The bearing is a magnetic bearing, and the heat generation control means controls a bias current superimposed on a control current of the magnetic bearing.
The pump device according to. 3. The pump device according to claim 1, wherein the bearing is a magnetic bearing, and the heat generation control unit controls a high frequency current superimposed on a control current of the magnetic bearing. 4. The heat generation control means controls the heat generation amount of the motor by varying the rotation speed of the motor, according to claim 1, claim 2, or claim 3. Pump device. 5. The cylindrical member, the base member, the rotor, and the stator are made of aluminum or an aluminum alloy, according to any one of claims 1 to 4. The pump device according to claim. 6. The pump device according to claim 5, wherein the reinforcing member arranged around the motor or the exterior member of the bearing is made of aluminum or an aluminum alloy. 7. The coating according to claim 1, wherein at least a part of the facing surfaces of the stator and the rotor are coated with a material for increasing efficiency of heat radiation. The pump device according to claim 1. 8. The at least part of the outer peripheral surface of the cylindrical member faces the inner peripheral surface of the rotor with a predetermined gap, and at least part of the opposing surfaces of the cylindrical member and the rotor. The pump device according to any one of claims 1 to 7, further comprising a coating for increasing heat radiation efficiency. 9. A cooling means formed on the pump device, and a cooling control means for controlling the cooling means in relation to a temperature detected by a temperature detecting means installed at a predetermined position of the pump device. Claim 1 thru | or 8 characterized by having provided.
The pump device according to claim 1.