JP2902454B2 - Driving method of rotating body provided with shaft sealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention rotationally drives a rotating body that rotates while being sealed by a shaft sealing device, for example, a magnetic fluid shaft sealing device, a fluid sealing shaft sealing device, or the like. For the driving method.

[Prior Art] The above-mentioned shaft sealing device for fluid sealing contacts the outer peripheral surface of a rotating body under a constant pressure, for example, like rubber packing,
It prevents fluid, for example, cooling water, from leaking and flowing along the rotating body.

Conventionally, when rotating a rotary body sealed by this type of fluid sealing shaft sealing device, the rotary body is instantaneously raised to a predetermined set rotation speed. According to this conventional driving method, the rubber packing or the like is deformed or worn in a short period of time, so that it was not possible to maintain a good shaft sealing ability for a long period of time.

The magnetic fluid shaft sealing device is to maintain a fluid pressure difference around the rotating body using a magnetic fluid,
For example, the structure shown in FIG. 4 is known. The magnetic fluid shaft sealing device 1 shown here has a substantially cylindrical case 15.
And a plurality of annular magnets 2 arranged in parallel with each other in the case 15 and an annular magnetic member 3 disposed between the respective magnets 2. The rotating shaft 4 sealed by the magnetic fluid shaft sealing device extends through the magnets 2 and the magnetic members 3 in the left-right direction in the drawing, and one (left side) of the rotating shaft 4 is located in the low-pressure region Q. , The other (right side) is located in the high pressure region P. The rotating shaft 4 is driven by driving means (not shown) and rotates as indicated by an arrow A.

A magnetic fluid 5 is placed between each magnetic member 3 and the rotating shaft 4. Each magnet 2 is arranged so that the same pole of the N pole and the S pole is adjacent to each other, and the magnetic flux lines coming out of the N pole of each magnet 2 , Magnetic fluid 5 and each magnet 2
A circulation path reaching the S pole of the circulator is formed. Due to the magnetic flux lines, the magnetic fluid 5 is attracted to both the rotating shaft 4 and the magnetic member 3 by magnetic force, whereby the rotating shaft 4 is sealed.
That is, while the rotating shaft 4 rotates, the magnetic fluid 5 prevents the gas in the high pressure region P, such as air, from leaking to the low pressure region Q.

By using this magnetic fluid shaft sealing device, it is possible to reliably prevent gas from leaking from the high pressure region P to the low pressure region Q. In addition, wear of the rotating shaft 4 is small, and a long life is ensured.

Conventionally, when the rotating shaft sealed by the magnetic fluid shaft sealing device 1 is driven to rotate, the low pressure region Q
The air in the chamber is exhausted to make the area in a reduced pressure state, for example, a vacuum state, and in this state, the rotating body is instantly raised to a predetermined set rotation speed. However, in this driving method, there is a problem that the magnetic fluid 5 is scattered and the sealing ability is significantly reduced in a short period of time.

One possible cause of such scattering of the magnetic fluid 5 is that a large centrifugal force acts on the magnetic fluid 5 rotating together with the rotating shaft 4. It is also considered that air remaining between the magnet 2 and the rotating shaft 4 and between the magnetic member 3 and the rotating shaft 4 is instantaneously drawn to the low pressure region Q side.

[Problems to be Solved by the Invention] As described above, a rotating body including a shaft sealing device such as a magnetic fluid shaft sealing device or a fluid sealing shaft sealing device maintains a high sealing ability for a long period of time. There was a problem that it was difficult. In particular, when the rotation speed of the rotating body is high, the problem has been prominent.

The present invention has been made in view of the above-mentioned problems in the conventional rotating body driving method, and provides a rotating body driving method capable of maintaining the sealing ability of the shaft sealing device satisfactorily for a long period of time. The purpose is to:

[Means for Solving the Problems] In order to solve the above object, the first driving method of the rotating body according to the present invention is such that the low pressure region where one side of the rotating body is located is already in a reduced pressure state. In this case, the rotating speed of the rotating body is not increased instantaneously to a desired set rotating speed, but is gradually increased.

Further, the second driving method of the rotating body may be configured such that when the low-pressure region is already in a reduced pressure state, the rotating speed of the rotating body is set to
Once the speed is increased to an intermediate speed lower than the desired set speed and maintained for a certain period of time, and then increased to the set speed above, that is, the speed of the rotating body is instantaneously increased to the desired speed. Rather, it is characterized by gradually raising it stepwise.

The first and second rotating body driving methods include a rotating body sealed only by a magnetic fluid shaft sealing device, or a shaft sealing device for fluid sealing, for example, a rotating body sealed only by rubber packing, Alternatively, the present invention can be applied to any of the rotating bodies sealed by both the magnetic fluid shaft sealing device and the fluid sealing shaft sealing device.

In particular, when applied to a rotating body sealed by both shaft sealing devices, when gradually increasing the rotating speed of the rotating body in a step-like manner as described above, it is not a one-step speed-up step. Preferably, the rotating body is raised to a predetermined set rotational speed through two stages of speed-up steps. That is, first, the rotation speed of the rotating body is increased to the first intermediate rotation speed, and the speed is maintained for a certain period of time. Then, the speed is increased to the second intermediate rotation speed, and the speed is maintained for a predetermined time. It is preferable to use a driving method of increasing the rotation speed to the set rotation speed.

The third method of driving a rotating body according to the present invention is characterized in that, when the low-pressure region is not yet in a reduced pressure state, the rotating body is in an exhaust process for reducing the low-pressure region to a reduced pressure state. Is characterized by rotating. In this case, the rotation of the rotating body may be continuously performed during the exhaust processing while the exhaust processing is being performed. Alternatively, the rotation may be stopped after a certain period of time has elapsed since the start of the rotation.

In this specification, the low-pressure region and the high-pressure region relatively represent whether one pressure atmosphere (low-pressure region) is lower or higher than the other pressure atmosphere (high-pressure region). However, it does not express specific numerical values such as lower or higher than normal atmospheric pressure.

The magnetic member is a member having a property of being magnetized when a magnetic field is applied, that is, a member having a property of being able to pass a magnetic flux line emitted from a magnet.

The magnetic fluid is a fluid formed by dispersing magnetic metal fine particles in a non-magnetic fluid medium in a colloidal state. For example, a fluid in which ferrite or other magnetic powder is dispersed in a liquid such as hydrocarbon, fluorine hydrocarbon, or fatty acid can be used.

[Operation] The driving method according to claims 1 and 2 is directed to a rotating body sealed by a magnetic fluid shaft sealing device (1).
It is assumed that the low pressure region (Q) is already in a reduced pressure state, for example, a vacuum state. In this case, the rotating speed of the rotating body (target rotating shaft 21) is gradually increased (see FIG. 3).
a, b), or by stepwise raising (Fig. 3b), the residual air remaining in the magnetic fluid shaft sealing device (1) is gradually vented into the low pressure region.

The driving method according to claims 3 and 4 is directed to a rotating body sealed by a magnetic fluid shaft sealing device (1).
It is assumed that the low pressure region (Q) is not yet in a desired reduced pressure state, for example, a vacuum state, and an exhaust process is performed to obtain the desired reduced pressure state. In this case, the rotating body (21) Are rotated during the exhaust process (FIGS. 3c and 3d). The low pressure area (Q) is gradually reduced in pressure according to the exhaust processing. On the other hand, magnetic fluid shaft sealing device (1)
The residual air inside is gradually drawn into the low-pressure region according to the rotation of the rotating body and according to the pressure in the low-pressure region that is gradually reduced.

The driving method according to claims 5 and 6 is directed to a rotating body sealed by a fluid sealing shaft sealing device (packing 26). By gradually increasing the rotation speed of the rotating body (the target rotating shaft 21) (FIGS. 3a and 3b) or stepwise (FIG. 3b), the fluid sealing shaft sealing device is gradually increased. To prevent deformation and wear of the shaft sealing device.

The driving method according to claims 7 and 8 is intended for a rotating body sealed by both the magnetic fluid shaft sealing device (1) and the fluid sealing shaft sealing device (packing 26). Especially,
In the method according to claim 8, the rotating body is accelerated to a desired set rotational speed through at least two speed increasing steps (FIG. 3B). In the first speed-up step, either one of the air bleeding process for the magnetic fluid shaft sealing device and the adaptation process for the fluid sealing shaft sealing device is executed. Then, in the second speed increasing step, the other one of the processes is executed.

Embodiment FIG. 1 schematically shows an embodiment in which the method for driving a rotating body according to the present invention is applied to an X-ray generator used in an X-ray diffractometer or the like.

The X-ray generator described here is composed of an X-ray tube tube 6 which is a prismatic closed container, a target unit 8 having a rotor target 7, and a vacuum decompression means provided below the X-ray tube tube 6. 9.

The outside of the X-ray tube 6 is a high-pressure region P, which is set to the atmospheric pressure. On the other hand, the inside of the X-ray tube tube 6 is in a low-pressure region Q, and the inside of the X-ray tube tube 6 is evacuated by evacuating the air by the vacuum evacuation means 9.

As the evacuation means 9, any structure can be used, but in the case of the embodiment, a rotary pump 10 is used.
The exhaust gas is rough-evacuated, and the final and complete evacuation is performed by the turbo-molecular pump 11, so that a highly accurate vacuum can be obtained. The operations of the rotary pump 10 and the turbo molecular pump 11 are controlled by the control device 12.

A filament 13 is provided above the low pressure region Q. A high voltage is applied between the filament 13 and the rotor target 7 by a high-voltage power supply (not shown), and a current is supplied to the filament 13 by a current source (not shown). The current is applied to the filament 13 to generate heat, from which electrons are emitted. The emitted electrons are the filament 13 and the target 7
The target 7 is accelerated by the potential difference between the target 7 and collides with the target 7, from which X-rays are emitted. X-rays emitted are X
The tube is taken out from an X-ray take-out window 14 provided in advance on the left side surface of the tube tube 6.

As shown in FIG. 2, the target unit 8 includes a cylindrical housing 17 airtightly fixed to a flange 16 fixed to the X-ray tube 6, and a drive motor 18 fixed to the right side of the housing 17. And a water supply / drainage connector 19 fixed to the right side of the drive motor 18.

Two bearings 20, 20 are fitted on the right side inside the housing 17, and the rotating shaft 21 of the target 7 is supported by these bearings. On the left side inside the housing 17, the magnetic fluid shaft sealing device 1 described in FIG. The pressure difference between the inside and outside of the X-ray tube 6 is maintained by the shaft sealing device 1. That is, leakage of air from the high-pressure region P set to the atmospheric pressure to the low-pressure region Q in a vacuum state is reliably prevented.

The drive motor 18 is connected to a case 22 fixed to the housing 17.
And a stator coil 23 fixed to the case 22 and a rotor 24 fixed to the outer peripheral surface of the target rotating shaft 21. When a current flows through the stator coil 23 based on an instruction from the control device 12, the rotor
A rotating magnetic field is formed around 24, and the rotor 24 rotates. When the rotor 24 rotates, the target rotating shaft 21 fixed thereto also rotates, and as a result, the target rotating shaft 21 rotates.
Rotor target 7 attached to the left end of 21
Rotates.

The target rotation shaft 21 is hollow, and a water passage pipe 25 is inserted therein at regular intervals. The water pipe 25 is also hollow. Target rotation axis
The right end of 21 is rotatably connected to water supply / drainage connector 19 via packing 26. A water passage 28 is formed inside the water supply / drain connector 19, and the target rotating shaft 21 and the drain pipe 29 communicate with each other via the water passage 28.
On the other hand, the water pipe 25 penetrates the center of the water supply / drain pipe 19 and is connected to the water supply pipe 27.

The water supply pipe 27 is connected to a water supply source (not shown), and cooling water is supplied from the water supply source. The supplied cooling water passes through the water pipe 25 to the left in the figure, and flows along the inner peripheral surface of the rotor target 7 to cool the rotor target 7, and then cools the target rotating shaft. It returns to the right side of the figure through the space between 21 and the water pipe 25, and is finally discharged to the outside through a water passage 28 in the water supply / drain connector 19 and a drain pipe 29 communicating therewith.
The packing 26 prevents the cooling water from leaking to the outside.

Hereinafter, control of the operations of the vacuum pressure reducing means 9 and the target drive motor 18 performed by the control device 12 will be described.

In order to operate the X-ray generator of FIG. 1, it is necessary to first depressurize the inside of the X-ray tube 6, that is, the low pressure region Q to a vacuum state. Therefore, at timing t0 in FIG. 3, the rotary pump 10 and the turbo molecular pump 11 are turned on, and the air in the low-pressure region Q is gradually exhausted. This evacuation process is continuously performed for about 2 hours, and a desired vacuum state is obtained at the timing t1.

When the low pressure region Q is in a vacuum state, the rotor target 7
It is possible to perform the described X-ray radiation processing while rotating. FIG. 3 exemplifies four different methods (a) to (d) as a method of driving the rotation of the rotor target 7. Hereinafter, they will be individually described.

Driving method (a) In this method, after a vacuum state is obtained at timing t1,
At an appropriate timing t2 when it is desired to start the rotation of the target 7, the rotation of the drive motor 18, that is, the target rotating shaft 21 is started. In this case, the control device 12 gradually raises the rotation of the target rotation shaft 21 and controls so as to reach a desired rotation speed r1, for example, 8,000 to 10,000 rpm in about 8 seconds.

According to the conventional driving method, the target rotation shaft 21 is instantaneously raised to the desired rotation speed r1 as shown by the broken line. According to this conventional method, the target rotating shaft 21, that is, the rotating shaft 4 is instantaneously rotated at a high speed in FIG. 4, so that a large centrifugal force is applied to the magnetic fluid 5, and as a result, the magnetic fluid 5 is scattered. As a result, a desired sealed state may not be obtained.

Further, even after the evacuation process performed during the time (t0-t1) in FIG. 3 is completed, the inside of the magnetic fluid shaft sealing device 1, that is, between the magnet 2 and the target rotating shaft 21, and between the magnetic member 3 Air remains between the target rotating shaft 21 and the target rotating shaft 21. When the target rotary shaft 21 is instantaneously rotated at a high speed as in the conventional case, the residual air instantaneously turns into the low pressure region Q.
It is considered that the magnetic fluid 5 is also scattered.

On the other hand, according to the driving method of this embodiment shown by the solid line in FIG. 3A, the rotation speed of the target rotation shaft 21 is gradually increased, so that a large centrifugal force is applied to the magnetic fluid 5. Nothing. In addition, the residual air in the shaft sealing device 1 is gradually drawn without being instantaneously drawn into the low pressure region Q. That is, gentle air bleeding can be performed. Therefore, scattering of the magnetic fluid 5 is prevented.

As shown in FIG. 2, in this embodiment, the right end of the target rotating shaft 21 is in contact with the packing 26 under a constant pressure. If the rotation speed of the target rotating shaft 21 is rapidly increased as in the conventional method, water leakage occurs at the packing 26, or the packing 26 wears out in a short period of time, so that a long life cannot be secured. was there. In contrast, according to the present embodiment, the target rotation axis
Since the rotation speed of 21 gradually rises, no excessive force is applied to the packing 26, and the packing 26 naturally becomes the target rotation shaft 21. Therefore, the above-mentioned problems such as water leakage and wear can be solved.

Driving Method (b) In the driving method shown in FIG. 3 (b), instead of gradually increasing the rotation speed of the target rotation shaft 21 at a constant acceleration as shown in FIG. so-called step-up, in which the speed is increased to r2 and held at that low speed r2 for a certain period of time, then increased to medium speed r3 and held for a certain period of time at that speed r3, and finally increased to the desired rotation speed r1 Has become the way.

In this case, the first speed-up step of increasing the speed to the low speed r2 is mainly for causing the packing 26 to fit into the target rotating shaft 21 to prevent water leakage and wear.
On the other hand, the second speed-up step in which the speed is increased to the medium speed r3 is mainly for slowly bleeding the air in the magnetic fluid shaft sealing device 1. Therefore, specific numerical values of the low speed r2 and the medium speed r3 can be set to arbitrary values provided that their functions are achieved.

In addition, the speed rise times t3 and t5 in the first and second speed-up steps and the constant speed holding time t4 and
t6 is appropriately set according to the properties of the magnetic fluid 5, the material of the packing 26, the values of the set low speed r2 and medium speed r3, and other various conditions.

Driving Method (C) The driving method shown in FIGS. 3 (a) and 3 (b) is a method of rotating the target rotating shaft 21 as a rotating body after the low-pressure region Q has already been in a vacuum state. It was that. On the other hand, in the driving method shown in (C), the low-pressure area Q is not yet in a vacuum state, and the target rotating shaft is being rotated while the low-pressure area Q is being evacuated to a vacuum state. It is how to rotate 21.

That is, in this driving method, the drive motor 18 is started only when a desired timing t2 at which it is desired to generate X-rays arrives, that is, the target rotating shaft 21
Instead of starting the rotation of the motor, the drive motor 1
8 has also started.

At the timing t0, the low-pressure region Q is not yet in a vacuum state but is at atmospheric pressure. Therefore, even if the target rotating shaft 21 is instantaneously started at this time, residual air in the magnetic fluid shaft sealing device 1 is not removed. The residual air is not instantaneously extracted to the low-pressure region Q, and the residual air is gradually exhausted. Therefore, scattering of the magnetic fluid 5 is also prevented.

In this driving method, the initial rotation speed r4 of the target rotation shaft 21 for removing the residual air can be equal to the set rotation speed r1 during normal operation. However, if the rotation speed r4 is too high, the packing 26
It is difficult to adapt to the target rotation shaft 21. Therefore, it is preferable that the initial rotational speed r4 be lower than the set rotational speed r1 during operation.

Driving method (d) This driving method is similar to the driving method (c) described above, except that the target rotating shaft 21 is rotated while the evacuation process for evacuating the low-pressure region Q is performed. Or let them do that.

This driving method is different from the above driving method (c) in that the rotation of the target rotating shaft 21 started at the timing t0 is stopped at an appropriate timing t7. The time for rotating the target rotating shaft 21 from t0 to t7 is set to a time during which the residual air in the magnetic fluid shaft sealing device 1 can be completely vented.

As described above, the time required for the evacuation process for evacuating the low-pressure region Q requires a very long time, such as two hours. Therefore, it is uneconomical to continuously rotate the target rotation shaft 21 at the rotation speed r4 during the exhaust processing as in the driving method (c) described above. On the other hand, if the rotation of the target rotary shaft 21 is stopped after the air release from the target magnetic fluid shaft sealing device 1 is completed as in the present driving method (d), the shaft sealing device 1 It is possible to achieve the initial object of preventing the magnetic fluid 5 from being scattered in the inside, and to operate the apparatus economically by avoiding unnecessary rotation of the target rotation shaft 21.

When the pumps 10 and 11 are started (at timing t)
0), the pressure in the low pressure region Q is still the atmospheric pressure. Therefore, even if the rotation of the target rotating shaft 21 is started at the same time, the bleeding of the residual air does not start immediately.
Therefore, as shown by the broken line in the drawing, the rotation of the target rotation shaft 21 can be started with a delay of an appropriate time t8.

[Effects of the Invention] According to the first and second aspects of the invention, when the low pressure region is already in a reduced pressure state (for example, a vacuum state), the rotating body in contact with the magnetic fluid is instantaneously rotated at a high speed. Instead of gradually increasing the rotation speed, it is possible to gradually vent residual air remaining in the magnetic fluid shaft sealing device into the low pressure region, and as a result,
The scattering of the magnetic fluid can be prevented, and a good shaft sealing function can be maintained for a long period of time. Further, since a large centrifugal force is not applied to the magnetic fluid, the scattering of the magnetic fluid can be prevented from this point as well.

According to the third and fourth aspects of the present invention, the residual air is gradually vented into the low-pressure area while the low-pressure area is being exhausted. Unlike the conventional case, the residual air is not instantaneously drawn into the low pressure region, so that the magnetic fluid does not scatter.

According to the fifth and sixth aspects of the present invention, the shaft sealing device for fluid sealing can be gradually adapted to the rotating body, so that the shaft sealing device is prevented from being deformed and worn, and is good for a long period of time. A simple shaft sealing function can be maintained.

According to the seventh and eighth aspects of the present invention, with respect to the rotating body sealed by both the magnetic fluid shaft sealing device and the fluid sealing shaft sealing device, both shaft sealing functions are favorably maintained for a long period of time. can do. In particular, claim 8
According to the invention, since the unique speed-up step is provided for each shaft sealing device, the shaft sealing function of both shaft sealing devices can be maintained more reliably.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an apparatus for carrying out the method according to the present invention, FIG. 2 is a side sectional view showing a main part of the embodiment, and FIG. FIG. 4 is a side sectional view showing one example of a magnetic fluid shaft sealing device. DESCRIPTION OF SYMBOLS 1 ... Magnetic fluid shaft sealing device, 2 ... Magnet, 3 ... Magnetic member, 4 ... Rotating shaft, 5 ... Magnetic fluid, 9 ... Vacuum decompression means, 10 ... Rotary pump, 11 ... Turbo molecule Pump, 21: target rotation axis, P: high pressure range, Q:
Low pressure area

Claims (8)

(57) [Claims] 1. A driving method for driving a rotating body, one of which is located in a low pressure region and the other is located in a high pressure region with a magnetic fluid shaft sealing device as a boundary, wherein the magnetic fluid shaft sealing device comprises: A magnetic member disposed opposite to the rotating body, a magnetic fluid disposed between the magnetic member and the rotating body, and a magnet forming a magnetic member, a magnetic fluid and a magnetic flux line passing through the rotating body. The driving method is characterized in that the rotating speed of the rotating body is gradually increased to a desired set rotating speed when the low-pressure region is already in a reduced pressure state. 2. A driving method for driving a rotating body, one of which is located in a low pressure region and the other is located in a high pressure region with a magnetic fluid shaft sealing device as a boundary, wherein the magnetic fluid shaft sealing device comprises: A magnetic member disposed opposite to the rotating body, a magnetic fluid disposed between the magnetic member and the rotating body, and a magnet forming a magnetic member, a magnetic fluid and a magnetic flux line passing through the rotating body. In the driving method, when the low-pressure region is already in a reduced pressure state, the rotation speed of the rotating body is temporarily increased to an intermediate rotation speed lower than a desired set rotation speed, and the speed is held for a certain period of time. And thereafter increasing the rotation speed of the rotating body to the above-mentioned set rotation speed. 3. A driving method for driving a rotating body one of which is located in a low pressure region and the other is located in a high pressure region with a magnetic fluid shaft sealing device as a boundary, wherein the magnetic fluid shaft sealing device comprises: A magnetic member disposed opposite to the rotating body, a magnetic fluid disposed between the magnetic member and the rotating body, and a magnet forming a magnetic member, a magnetic fluid and a magnetic flux line passing through the rotating body. The driving method is characterized in that when the low-pressure region is not yet in a reduced pressure state, the rotating body is rotated while an exhaust process is performed to reduce the low-pressure region to a reduced pressure state. The driving method of the rotating body. 4. A method for driving a rotating body according to claim 3, wherein a predetermined time has elapsed after the rotating body started rotating.
A method of driving a rotating body, wherein the rotation of the rotating body is stopped before the low-pressure region reaches a desired reduced pressure state. 5. A driving method for driving a rotating body that rotates while being in contact with a shaft sealing device for fluid sealing, wherein the fluid leaks and flows along the rotating body in the shaft sealing device for fluid sealing. The driving method described above is characterized in that the rotation speed of the rotating body is gradually increased to a desired set rotation speed. 6. A driving method for driving a rotating body that rotates while being in contact with a shaft sealing device for fluid sealing, wherein the fluid leaks and flows along the rotating body in the shaft sealing device for fluid sealing. In the driving method, the rotation speed of the rotating body is temporarily increased to an intermediate rotation speed lower than a desired set rotation speed, and the rotation speed is held for a certain period of time. A method of driving a rotating body, wherein the speed is increased to the set rotation speed. 7. A rotating body which is located in a low pressure region and another in a high pressure region with a magnetic fluid shaft sealing device as a boundary, and which rotates while contacting the fluid sealing shaft sealing device. The magnetic fluid shaft sealing device according to claim 1, wherein the magnetic fluid shaft sealing device comprises: a magnetic member disposed to face the rotating body; a magnetic fluid disposed between the magnetic member and the rotating body; a magnetic member; And a magnet that forms a magnetic flux line passing through the rotating body. The fluid sealing shaft sealing device is for preventing fluid from leaking and flowing along the rotating body. A method of driving a rotating body, characterized by gradually increasing the rotating speed of the rotating body to a desired set rotation speed. 8. A rotating body which is located at a low pressure region and the other is located at a high pressure region with a magnetic fluid shaft sealing device as a boundary and rotates while contacting with the fluid sealing shaft sealing device. The magnetic fluid shaft sealing device according to claim 1, wherein the magnetic fluid shaft sealing device comprises: a magnetic member disposed to face the rotating body; a magnetic fluid disposed between the magnetic member and the rotating body; a magnetic member; And a magnet that forms a magnetic flux line passing through the rotating body. The fluid sealing shaft sealing device is for preventing fluid from leaking and flowing along the rotating body. When the low pressure region is already in a reduced pressure state, the rotation speed of the rotating body is increased to a first intermediate rotation speed lower than a desired set rotation speed, the speed is held for a certain period of time, and then the second intermediate rotation speed is reached. Increase the speed and hold it for a certain time, then The driving method of the rotating body the rotation speed of the rotating body, characterized in that it increased to the set rotational speed of the.