JPS63124897A - Turbo molecular pump device - Google Patents

Abstract

PURPOSE:To prevent a rotary shaft from coming into contact with a touch down bearing, by detecting the displacement of the rotary shaft from the reference position while outputting a signal of returning the rotary shaft to a desired position and controlling a magnetic bearing. CONSTITUTION:A device detects the displacement of a rotary shaft 17 in its radial direction by a displacement detecting sensor 19 to be output to a controller. The controller outputs a signal of returning the rotary shaft to the desired position in response to a value of the displacement on the basis of a signal from the sensor 19 to be input to magnetic bearings 20, 21. Accordingly, the rotary shaft can be rotated in a high speed being prevented from coming into contact with a touch down bearing even when no agreement is made between the center axis of the rotary shaft and the perpendicular direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a turbo-molecular pump (vacuum pump) device for realizing high vacuum in semiconductor manufacturing equipment and the like.

[Conventional technology]

FIG. 3 is a cross-sectional view showing a schematic configuration of a conventional turbo molecular pump device disclosed, for example, in the specification of Japanese Utility Model Application No. 1988-78395. In this figure, (1) is a rotor blade connected to the rotating shaft Q7). (2) is the rotor blade (1)
The stator blades are arranged opposite to the casing (3).
installed on. (4) is the rotor of the electric motor, which is attached to the rotating shaft 0η. That is, the rotor blade flll,
The rotation axis αη and the rotor (4) constitute a rotating body. (5) is a stator of the electric motor, which is fixed to the frame Ql. (7) is an exhaust port for exhausting all the fluid (air in most cases) inside the device to the outside of the device.

(9) is a base that supports the entire device.

The spherical spiral groove bearing 03 having an oil damper is lubricating oil with a very low saturated vapor pressure, and the spherical spiral groove bearing Oa forms a lower bearing. +1
Reference numeral 41 denotes a touchdown bearing for protection, which normally supports the rotating shaft aη when the rotating body starts rotating, and is not used during steady rotation.

The α bolt is a flange for attaching the turbomolecular pump device to the vacuum device.

Next, the operation will be explained. The rotor blade (1) is electrically
(When driven through 41 and +51, in the region where the rotation speed is low, it rotates while being supported by the lower bearing and the touchdown bearing placed at the top, but when the rotation speed increases, the gyro effect of the rotating body causes a touchdown. It comes off the bearing (141) and becomes non-contact, and is supported and rotated only by the lower spherical spiral groove bearing (2).When the rotor blade fi+ rotates at high speed, the fluid outlet of the device is released from the rotor blade (11
The air is exhausted to the outside air through the gap between the stator blades (2) and the pressure inside the device gradually decreases to achieve a vacuum state. iI always, rotor blade (1) and stator H (2)
The shape has been devised to form a flow α0 in the − direction.

[Problem that the invention seeks to solve]

The conventional turbo molecular pump device is configured as described above.
Due to the gyroscopic effect of the rotating body, the rotating body becomes self-supporting and rotates while being supported only by the lower spherical spiral groove bearing @, with its axis of rotation αη oriented in the vertical direction, that is, in the direction of gravity. For this reason, if the central axis of this turbo-molecular pump device is installed in a vacuum chamber with an inclination from the vertical direction, the rotating shaft rotates at high speed while contacting the touchdown bearing α, and the touchdown bearing There were problems such as damage and predetermined performance not being obtained.

This invention was made to solve the above-mentioned problems, and even when the central axis of the turbo molecular pump ttH is installed in a vacuum device with an inclination from the vertical direction, the rotating shaft and touchdown bearing can be fixed. The object of the present invention is to obtain a turbomolecular device that can rotate at high speed without contact and can obtain a specified performance as a vacuum pump.

[Means for solving problems]

A turbo-molecular pump device according to the present invention includes a casing having stator blades, a rotating body having rotor blades that are disposed opposite to the stator blades and suck fluid during rotation, and a rotor fixed to the rotating body. driving electric motor,
a lower bearing formed of a spherical spiral groove bearing that supports the rotating body at its lower part; a displacement detection sensor that detects displacement of the rotating shaft of the rotating body from a reference position; A controller that outputs a signal to return the rotary shaft to a desired position in response to a displacement value, and a magnetic bearing and touch that generate power to return the rotary shaft to the desired position based on the signal from the controller. It has an upper bearing with a down bearing.

[Effect]

The displacement detection sensor in this invention detects the displacement of the rotating shaft of the rotating body from the reference position, and the controller sends a signal to return the rotating shaft to the desired position in response to the displacement value based on the signal from the displacement detection sensor. The magnetic bearing generates the power to return the rotating shaft to its original position based on the signal from the controller, so even if the rotating shaft is installed at an angle from the vertical direction, the rotating shaft will remain at the reference point during high-speed rotation. This prevents the bearing from coming into contact with the touchdown bearing due to deviation from its position, thereby achieving the desired performance.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, α is a displacement detection sensor that detects the displacement in the radial direction of the rotation axis αη, that is, the displacement from the reference position. installed. (20>
, (21) are magnetic poles that are arranged opposite to each other and constitute a magnetic bearing, and are respectively installed on the frame [alpha] and the rotation axis [alpha]. In this example the magnetic pole (20) is
At least two pairs are installed in the X-axis direction and the Y-axis direction. FIG. 2 is an explanatory diagram illustrating the arrangement and operation of the displacement detection sensor and the magnetic bearing. In the figure, (19a) is
Displacement detection sensor that detects displacement in the axial direction (19b)
is a displacement detection sensor that detects displacement in the Y-axis direction, (20
a) is a magnetic pole that generates power in the X-axis direction, (20b)
is a magnetic pole that generates power in the Y-axis direction. (22) a controller that outputs a signal to return the rotating shaft to a desired position in response to the displacement value based on the signals from the displacement detection sensors (19a) and (19b); (23) is the controller (22); This is an amplifier that amplifies the signal from the magnetic bearings (20a) and (20b) to drive the magnetic bearings (20a) and (20b). In addition, in this figure, for explanation,
Axis, Y-axis circumferential displacement detection sensor (19a), (19b)
Although they are shown arranged one above the other, they are actually arranged at the same height and in orthogonal directions. In addition, a magnetic bearing (20a
) and (20b). Magnetic bearing (
21) is a magnetic bearing (20a), (2
0b) may be continuously provided in a ring shape, or may be provided in a divided manner.

Next, the operation will be explained. When the central axis of the turbo molecular pump device coincides with the vertical direction, that is, when the displacement from the reference position detected by the displacement detection sensors (19a) and (19b) is zero (for example, the displacement detection sensor (19a)
), (19b) to the axis of rotation aη is a predetermined value), then the magnetic bearings (20a), (20b
) (21) is not driven, and similarly to the conventional example, the rotary shaft joint is supported by the lower bearing surface, does not contact the touchdown bearing, rotates independently at high speed, and exhibits a predetermined performance.

On the other hand, if the central axis of the turbo molecular pump device does not match the vertical direction, that is, the displacement detection sensor (19a)
, (19b) when a displacement from the reference position is detected (for example, the distance from the displacement detection sensor (19a), (19b) to the rotation axis Q71 is shorter or longer than a predetermined value), the controller ( 22) responds to the displacement value based on the signals from the displacement detection sensors (19a) and (19b) to move the rotation axis to a desired position (for example, from the displacement detection sensors (19a) and (19b) to the rotation axis αη outputs a signal that returns the distance to a predetermined value).

This output signal is amplified by the amplifier (23) and the magnetic bearing (
20a) and (20b), and the magnetic bearing (20
a) Due to the actions of (20b) and (21), the axis of rotation α
η is returned to the desired position.

The configuration and operation of the controller (22) can be found, for example, in the catalogs N.C.N. Toyo Bearing Co., Ltd., N.C.N.
CAT, No. 8009 [Magnetic Bearing Spindle]” and the literature “IEI! E spectrum
rumSIEPTEMBER1979rPractic
It is specifically described in ``Al magnetic bearings''.

In addition, the displacement detection sensor O1 and the magnetic pole (20), (
The mounting position of 21) is not limited to the position shown in the above embodiment, but may be provided anywhere above the spherical spiral groove bearing side, and the same effect as in the above embodiment can be achieved.

Furthermore, the number of displacement detection sensors aI may be two or more, and the number of magnetic bearings (20) and (21) may be two or more pairs.

〔Effect of the invention〕

As described above, according to the present invention, a casing having stator blades, a rotating body having rotor blades arranged opposite to the stator blades and sucking fluid during rotation, and a rotor fixed to the rotating body, A driving electric motor, a lower bearing formed of a spherical spiral groove bearing that supports the rotating body at its lower part, a displacement detection sensor that detects displacement of the rotating shaft of the rotating body from a reference position, and a signal from this displacement detection sensor. a controller that outputs a signal to return the rotary shaft to a desired position in response to the value of the displacement based on the value of the displacement, and generates power to return the rotary shaft to the desired position based on the signal from the controller. Equipped with an upper bearing that has a magnetic bearing and a touchdown bearing, it can rotate at high speed without contact between the rotating shaft and the touchdown bearing even if the central axis of the rotating body does not match the vertical direction, making it suitable for use as a vacuum pump. It has the effect of obtaining the specified performance of 6

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a turbo-molecular pump device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram explaining the operation of the main parts of FIG. 1, and FIG. 3 is a conventional turbo-molecular pump device. FIG. In the figure, (1) is a rotor blade, (2) is a stator blade,
(3) is the casing, (4) is the motor rotor, (5) is the motor stator, sub is the spherical spiral groove bearing, 04
) is a touchdown bearing, Q? ) is the rotation axis, (19),
(19a) and (19b) are displacement detection sensors, (2
0), (20a), (20b), (21)
is a magnetic bearing, (22) is a controller, and (23) is an amplifier.゛The same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] a casing having stator blades; a rotating body having rotor blades disposed opposite to the stator blades and sucking fluid during rotation; an electric motor having a rotor fixed to the rotating body and driving the rotating body; a lower bearing formed of a spherical spiral groove bearing, supported by a displacement detection sensor that detects displacement of the rotating shaft of the rotating body from a reference position;
a controller that outputs a signal to return the rotating shaft to a desired position in response to the displacement value based on the signal from the displacement detection sensor; and a controller that outputs a signal to return the rotating shaft to a desired position based on the signal from the controller A turbomolecular pump device with an upper bearing having a magnetic bearing and a touchdown bearing to generate power back into position.