JP2001304173A - Turbo-molecular pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo-molecular pump which has a valve element covering an inlet port provided to a casing so as to be capable of opening/closing, can constitute a whole of the turbo-molecular pump including a valve device to be reduced in size, and includes a valve driving mechanism in which high reliability in opening/closing of the valve element can be realized. SOLUTION: In this turbo-molecular pump, a rotor R and a stator S are stored inside the casing 13, and an exhaust passage is provided between the rotor R and the stator S. This turbo-molecular pump comprises: the valve element 15 covering the inlet port 14 provided to the casing 13 so as to be capable of opening/closing; and the valve driving mechanism driving the valve element 15. The valve driving mechanism 40 is constituted of a valve rod 30 inserted through at least a through hole formed in the rotor, an elevation mechanism comprised of a ball screw 44 and a ball screw nut 46, and a servomotor 43 for driving the elevation mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo-molecular pump in which gas is exhausted by a high-speed rotating blade and / or a thread groove rotor.

[0002]

2. Description of the Related Art FIG. 6 shows a general configuration of a conventional turbo-molecular pump. The turbo-molecular pump includes a rotor R having a main shaft 10 and a rotary cylindrical portion 11 that rotates integrally with the main shaft 10, a stator S having a fixed cylindrical portion 12 surrounding the main shaft 10, and surrounding the rotary cylindrical portion 11. A cylindrical casing 13 is assembled on a base B.
On the upstream side of the turbo molecular pump having such a configuration, a conductance adjusting valve 100 and an on-off valve (gate valve) 110 are provided between the turbo molecular pump and a device to be evacuated.

However, in the turbo molecular pump having the above configuration, the conductance adjusting valve 100 and the on-off valve 110
There is a problem that the drive mechanisms for driving the respective valves are provided close to each other, so that each valve device is enlarged, and the overall structure of the turbo-molecular pump including these valves is increased.

In order to solve the above problem, for example, Japanese Patent Application No.
As disclosed in JP-A-215645 and Japanese Patent Application No. 9-235437 and drawings, a valve body provided on a casing of a turbo-molecular pump so as to open and close an intake port, and a valve drive mechanism for opening and closing the valve body And a turbo molecular pump in which the entire structure including the valve device is made compact has been proposed. However, even in a turbo-molecular pump having a valve body that covers the intake port so as to be openable and closable, various problems arise as to how to specifically configure a valve drive mechanism that opens and closes the valve body. There is a problem that sufficient reliability cannot be obtained for the opening / closing operation of the valve element.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has a valve body provided on a casing for opening and closing an intake port, and the entire structure including a valve device is compact. It is an object of the present invention to provide a turbo-molecular pump having a valve drive mechanism capable of achieving high reliability in opening and closing a valve body.

[0006]

According to the first aspect of the present invention, a rotor and a stator are accommodated in a casing, and an exhaust passage is formed between the rotor and the stator. And a turbo-molecular pump including a valve drive mechanism for driving the valve body, the valve drive mechanism including at least a through-hole formed in the rotor. A supporting member, an elevating mechanism including a ball screw and a ball screw nut for elevating and lowering the valve element supporting member, and a motor for driving the elevating mechanism. Are fixed.

According to a second aspect of the present invention, a rotor and a stator are housed in a casing, an exhaust passage is formed between the rotor and the stator, and an intake port provided in the casing is openably and closably covered. In a turbo-molecular pump including a valve body and a valve drive mechanism that drives the valve body, the valve drive mechanism includes a plurality of valve body support members having at least one end fixed near an outer peripheral portion of the valve body; It is characterized by comprising a lifting mechanism including a ball screw and a ball screw nut for raising and lowering each of the body support members, and a motor for driving the plurality of lifting mechanisms.

As described above, the valve drive mechanism has the lifting mechanism composed of the ball screw and the ball screw nut, and the valve body is opened and closed via the valve body supporting member by the lifting mechanism. The valve element is opened / closed by a simple and extremely reliable lifting / lowering mechanism comprising: a highly reliable opening / closing operation of the valve element.

According to a third aspect of the present invention, there is provided the turbo-molecular pump according to the second aspect, wherein a guide shaft for guiding the lifting and lowering of the valve body support member is provided in parallel with the valve body support member. .

Since the guide shaft is provided in parallel with the valve body support member as described above, the valve body support member moves up and down smoothly along this guide shaft, so that the opening and closing operation of the valve body becomes smooth, and the minute The opening degree of the valve body can be adjusted.

The invention described in claim 4 is the first or second invention.
Alternatively, in the turbo-molecular pump described in 3, the sensor for detecting the amount of elevation of the valve body support member is provided.

By providing a sensor for detecting the amount of elevation of the valve element supporting member as described above, for example, by inputting the output of the sensor to the control device, the opening degree of the valve element, the upper limit of the opening degree, and the fully closed state And the like can be accurately controlled.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a turbo-molecular pump according to the present invention. The turbo molecular pump includes a rotor R having a main shaft 10 and a rotating cylindrical portion 11 rotating integrally therewith, a stator S having a fixed cylindrical portion 12 surrounding the main shaft 10, and a cylindrical shape surrounding the fixed cylindrical portion 12. And the casing 13 are assembled on the base portion B to form a turbo molecular pump main body. And the casing 13
A valve body 15 is provided to cover the intake port 14 in an openable and closable manner. The upper end flange 13a of the casing 13 is fixed to the duct 39 in an airtight state.

A drive motor 16 is disposed between the main shaft 10 and the fixed cylindrical portion 12, and an upper radial magnetic bearing 17 and a lower radial magnetic bearing 1 are provided above and below the drive motor 16.
8 are provided. A target disk 19 provided at a lower end of the main shaft 10 is provided below the main shaft 10.
An axial magnetic bearing 21 composed of upper and lower coils 20 on the stator S side is disposed. Thus, the rotor R rotates at a high speed under the active control of five axes with the driving of the driving motor 16.

On the outer periphery of the upper portion of the rotary cylindrical portion 11, a rotary blade 22 is provided.
Are integrally provided to form an impeller. On the other hand, on the inner surface of the casing 13, fixed wings 23 alternately arranged with the rotating wings 22 are provided. As a result, a blade exhaust unit 24 that exhausts air by interaction between the rotating blade 22 rotating at a high speed and the stationary blade 23 that is stationary is formed.

Further, the rotating tubular portion 11 has a fixed tubular portion 1.
A screw groove portion 25 extending downward along the outer periphery of 2 is provided integrally, and a screw groove 26 is provided on the outer peripheral surface of the screw groove portion 25. On the other hand, the stator S has this thread groove 2
A thread groove spacer 27 surrounding the outer periphery of the screw 5 is disposed. As a result, a screw groove exhaust portion 28 for exhausting by the drag action of the screw groove 26 of the screw groove portion 25 rotating at high speed is formed between the blade exhaust portion 24 and the exhaust hole 29.

The main shaft 10, the rotary cylindrical portion 11, and the base portion B
Is formed with a through hole 31 through which a valve stem 30 for opening and closing the valve element 15 is inserted. A valve drive mechanism 40 that drives the valve body 15 in the axial direction via the valve rod 30 is provided below the casing 13. The valve body 1 is provided at the intake port 14
An O-ring 32 that closes the air inlet 14 airtightly is provided at a position where the air inlet 5 contacts. The upper and lower portions of the valve stem 30 are supported by a magnetic bearing 33 and a linear bearing 34 so as to be vertically movable. The magnetic bearing 33 is supported by a support member 38 provided at the tip of a plurality of arms 37 extending from the casing 13 toward the center inside the intake port 14.

A thread exhaust portion 35 is formed between the valve stem 30 and the inner surface of the through hole 31 of the main shaft 10 surrounding the valve stem 30. The screw groove exhaust portion 35 is provided with a gap between the outer peripheral surface of the fixed cylindrical portion 12 and the rotary cylindrical portion 11 and a gap between the fixed cylindrical portion 12 and the main shaft 10, and a through hole 3.
1 to prevent the gas once exhausted from flowing back through the path leading to the intake port 14 via the valve rod 30.
A thread groove 36 is formed in a predetermined range on the outer peripheral portion of the screw.
By the rotation of the rotor R, a drag action works downward in the figure.

The valve drive mechanism 40 includes a servomotor (with an electromagnetic brake) 43 provided on a base plate 42 fixed via a support housing 41 fixed to a lower end (base portion B) of the casing 13, and a combined angular motor. A ball screw 44 rotatably provided via a ball bearing 51 is provided. Instead of the electromagnetic brake built in the servomotor 43, an electromagnetic brake 45 may be separately provided as shown in the figure. A ball screw nut 46 for screwing the ball screw 44 to the lower end of the valve stem 30 is fixed. A pulley 47 is provided on the rotation shaft of the servomotor 43, and the ball screw 4
A pulley 48 is fixed to the lower end of 4.

A timing belt 52 is suspended between the pulleys 47 and 48 so that the torque of the servo motor 43 is transmitted to the ball screw. The valve stem 30 between the ball screw nut 46 and the base portion B is surrounded by a bellows 54. When the electromagnetic brake 45 is provided separately, a pulley 50 is attached to the rotating shaft, and a timing belt 53 is suspended between the pulley 49 and the pulley 49 attached to the ball screw 44 so that the braking force is transmitted to the ball screw 44. .

In the valve driving mechanism 40 having the above-described structure, by rotating the servo motor 43 forward and backward, the rotational force is transmitted to the ball screw 44 via the pulley 47, the timing belt 52 and the pulley 48. Since the ball screw nut 46 moves up and down by the forward and reverse rotation of the ball screw 44, the valve stem 30 moves up and down integrally with this, and the valve body 15 is opened and closed. When the power of the servo motor 43 is cut off and stopped, the built-in electromagnetic brake is activated, and the braking force is transmitted to the ball screw 44 via the pulley 47, the timing belt 52 and the pulley 48, and the rotation of the ball screw 44 stops immediately. I do. When the separately provided electromagnetic brake 45 is provided, the power of the servo motor 43 is cut off and the power of the electromagnetic brake 45 is cut off at the same time, and the brake is operated and the braking force is applied to the pulley 50, the timing belt 53,
The rotation is transmitted to the ball screw 44 via the pulley 49, and the rotation is immediately stopped.

In the turbo-molecular pump having the above structure, since the upper portion of the valve stem 30 is levitated and supported in a non-contact manner by the magnetic bearing 33, the generation of particles due to abrasion hardly occurs, and therefore, the exhaust side may be contaminated. Absent. In addition, the valve stem 30
Is supported by the linear bearing 34, but this portion is located downstream of the screw groove exhaust portion 35, so that the exhausted side is not contaminated. Since the ball screw nut 46 and the valve stem 30 in the base portion B are surrounded by the bellows 54, particles generated in this portion do not scatter outside.

FIG. 2 is a diagram showing the structure of a vertical movement detecting mechanism for detecting the vertical movement of the valve rod 30. As shown in FIG. As shown in the figure, microphoto sensors 61 and 62 that penetrate the side wall of the support housing 41 and detect the end of the ball screw nut 46,
63 is provided to detect the elevation amount of the ball screw nut 46, that is, the elevation amount (valve opening) and the upper and lower limits of the valve body 15, and input the detected values to a control device (not shown). By stopping and stopping the power supply of the servo motor 43 and the built-in electromagnetic brake, it is possible to precisely control the amount of movement of the valve body 15 and the stop of the upper limit and the lower limit.

In the above example, the rotational force of the servo motor 43 and the braking force of the built-in or separate electromagnetic brake are transmitted via the pulley and the timing belt. Instead, a gear mechanism is used. You may comprise so that a rotational force and a braking force may be transmitted. In addition, when a timing belt is used, high precision and long life can be achieved by using a metal timing belt. For example, as the timing belt, a metal belt-shaped body having holes formed at predetermined regular intervals is used, and as the pulley, a belt provided with projections to be inserted into the holes at regular intervals is used.

FIGS. 3 to 5 are views showing examples of the structure of a turbo-molecular pump according to the present invention. 3 is a longitudinal sectional view, FIG. 4 is a view showing a partial configuration of a valve drive mechanism, and FIG. 5 is a sectional view taken along line AA of FIG. 3 to 5, the portions denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding portions, and the operation and operation thereof are substantially the same. The upper end flange 13a of the casing 13 of the turbo molecular pump is
The base plate 70 is attached to the lower end (base B) of the casing 13.

The valve body 15 is supported by a plurality of (two in the figure) valve stems 71 in the vicinity of the outer periphery thereof.
The ball screw nut 72 is fixed as shown in FIG.
A ball screw 73 is screwed into the ball screw nut 72. The lower end of the ball screw 73
The ball screw 73 is rotatably supported via a combined angular ball bearing 81, and a pulley 74 is fixed to the lower end of the ball screw 73. By rotating the ball screw 73, the ball screw nut 72 and the valve stem 71 integrated therewith are moved up and down.

A guide shaft 75 is provided between the upper end flange 13a of the casing 13 and the base plate 70 in parallel with the valve rod 71.
The valve shaft 71 is guided by the guide shaft 75 via a linear ball bearing 76 and moves up and down. That is, the linear ball bearing 76 is provided near the lower end of the valve stem 71.
And a guide bracket 71a for accommodating and fixing the
The valve shaft 71 is moved up and down by being guided by a guide shaft 75 via a guide bracket 71a and a linear ball bearing 76. As a result, the valve stem 71 moves up and down smoothly without occurrence of shake. Therefore, the valve element 15
Open and close smoothly. Reference numeral 77 denotes a stopper for regulating the elevation of the valve rod 71. The elevation is regulated when the guide bracket 71a comes into contact with the stopper 77.

Reference numeral 78 denotes a servomotor (with an electromagnetic brake) provided on the base plate 70, and a pulley 79 is attached to a rotating shaft of the servomotor 78.
And a pulley 74 attached to the lower end of the ball screw 73.
5, a timing belt 80 is suspended as shown in FIG.
0 and the respective ball screws 73 via pulleys 74, 74. That is, the valve stem 71, the ball screw nut 72, the ball screw 73, the pulleys 74 and 79, the servomotor 78, and the like constitute a valve drive mechanism of the turbo molecular pump.

In the above example, an example is shown in which a servomotor 78 with a built-in electromagnetic brake is used. However, as shown in FIG.
An electromagnetic brake may be provided separately. In FIG. 5,
Reference numeral 82 denotes an idler pulley for applying a constant tension to the timing belt.

Although not shown, the turbo molecular pump is also provided with a vertical movement detecting mechanism having a structure as shown in FIG. 2 for detecting the vertical movement of each valve rod 71. By inputting the information to the control device and stopping the driving of the servomotor 78 by the control device, it is possible to perform accurate stop control of the moving amount of the valve body 15 and the upper and lower limits.

In the turbo-molecular pump according to the present invention, the main body of the turbo-molecular pump is not limited to those shown in FIGS. 1 and 3, but the rotor and the stator are housed in a casing. An exhaust flow path is configured between the stator and the stator, and a configuration including a valve body that opens and closes an intake port provided in the casing is provided.
The specific configuration may be any.

[0032]

As described above, according to the invention described in each claim, the following excellent effects can be obtained.

According to the first aspect of the present invention, the valve drive mechanism is constituted by the valve body supporting member that passes through the through hole formed in the rotor, the lifting mechanism including the ball screw and the ball screw nut, and the motor. Therefore, the valve element is opened and closed by a simple and extremely reliable lifting mechanism including a ball screw and a ball screw nut, and a highly reliable valve element opening / closing operation is obtained.

According to the second aspect of the present invention, the valve drive mechanism includes a plurality of valve body support members having one end fixed to the vicinity of the outer peripheral portion of the valve body, a lifting mechanism including a ball screw and a ball screw nut. And the motor, the valve element is opened and closed by a simple and extremely reliable lifting mechanism composed of a ball screw and a ball screw nut, and a highly reliable valve element opening and closing operation can be obtained.

According to the third aspect of the present invention, since the guide shaft is provided in parallel with the valve body support member, the valve body support member moves up and down smoothly along the guide shaft, so that the valve body is opened and closed. The operation is also smooth, and the opening of the valve body can be finely adjusted.

According to the fourth aspect of the present invention, by providing a sensor for detecting the amount of elevation of the valve body support member, for example, by inputting the output of the sensor to the control device,
Control of the opening degree of the valve body, the upper limit of the opening degree, the fully closed state, and the like can be accurately performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a turbo-molecular pump according to the present invention.

FIG. 2 is a view showing a configuration of a vertical movement detecting mechanism for detecting a vertical movement of a valve stem of the turbo-molecular pump according to the present invention.

FIG. 3 is a diagram showing a configuration of a turbo-molecular pump according to the present invention.

FIG. 4 is a diagram showing a partial configuration of a valve drive mechanism of the turbo-molecular pump according to the present invention.

FIG. 5 is a sectional view taken along line AA of FIG. 3;

FIG. 6 is a diagram showing a general configuration of a conventional turbo-molecular pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Main shaft 11 Rotating cylindrical part 12 Fixed cylindrical part 13 Casing 14 Inlet 15 Valve body 16 Driving motor 17 Upper radial magnetic bearing 18 Lower radial magnetic bearing 21 Axial magnetic bearing 22 Rotating blade 23 Fixed wing 24 Blade exhaust part 28 Screw Groove exhaust part 29 Exhaust hole 30 Valve rod 33 Magnetic bearing 34 Linear bearing 35 Screw groove exhaust part 40 Valve drive mechanism 43 Servo motor (with electromagnetic brake) 44 Ball screw 45 Electromagnetic brake 46 Ball screw nut 47 Pulley 48 Pulley 49 Pulley 50 Pulley 51 Combination angular contact ball bearing 52 Timing belt 53 Timing belt 61 Micro photo sensor 62 Micro photo sensor 63 Micro photo sensor 71 Valve stem 72 Ball screw nut 73 Ball screw 74 Pulley 75 Guide shaft 7 Linear ball bearing 78 Servo Motor (with electromagnetic brake) 79 pulley 80 Timing belt

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[Procedure amendment]

[Submission date] April 26, 2000 (200.4.2
6)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

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FIG.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

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FIG. 3

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

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FIG. 6

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Matsutaro Miyamoto 11-1, Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Atsushi Shiokawa 11-1, Haneda Asahi-cho, Ota-ku, Tokyo EBARA F-term (reference) 3H021 AA01 AA08 BA00 BA11 BA20 CA05 DA10 EA04 3H031 DA01 DA02 DA07 EA00 EA12 EA15 FA38

Claims (4)

[Claims] 1. A valve body in which a rotor and a stator are accommodated in a casing, an exhaust passage is formed between the rotor and the stator, and a valve body for opening and closing an intake port provided in the casing is provided. In the turbo-molecular pump provided with a valve drive mechanism for driving the valve, the valve drive mechanism, at least a valve body support member that is inserted through a through hole formed in the rotor, a ball screw and a ball that moves up and down the valve body support member An elevating mechanism comprising a screw nut, and a motor for driving the elevating mechanism,
A turbo molecular pump, wherein a center portion of the valve body is fixed to the other end of the valve body support member. 2. A valve body in which a rotor and a stator are accommodated in a casing, an exhaust passage is formed between the rotor and the stator, and a valve body for opening and closing an intake port provided in the casing, and the valve body. In the turbo-molecular pump provided with a valve drive mechanism for driving the valve, the valve drive mechanism, a plurality of valve body support members at least one end of which is fixed near the outer peripheral portion of the valve body, each of the valve body support member A turbo-molecular pump comprising: a lifting mechanism including a ball screw and a ball screw nut for raising and lowering the motor; and a motor for driving the plurality of lifting mechanisms. 3. The turbo-molecular pump according to claim 2, wherein a guide shaft for guiding the lifting and lowering of the valve body support member is provided in parallel with the valve body support member. 4. The turbo-molecular pump according to claim 1, further comprising a sensor for detecting an amount of elevation of the valve body support member.