JPH048977A - Vacuum valve - Google Patents

Abstract

PURPOSE:To prevent generation of abrasive powder by composing a five-axes control magnetic bearing with magnetic bearings which consist of displacement sensors, a phase compensating circuit, and electromagnets, and holding a valve body to a valve seat by using the bearing in the noncontact condition. CONSTITUTION:A five-axes control magnetic bearing which consists of radial magnetic bearings A and A, and a thrust magnetic bearing B, detects a clearance between a valve seat 26 and a valve body 25, and a clearance between a rotary shaft 21 and a casing 20, depending on the signals from displacement sensors 6 and 13. The exciting currents of electromagnet exciting coils 5 and 12 are controlled by a phase compensating circuit and a power amplifier to make the clearances to specific values, the valve body 25 and the rotary shaft 21 are floated magnetically, and they are held in the noncontact condition to the valve seat 26 and the casing 20. When the valve is closed, the radial bearings A and A are controlled to rotate 90 deg. the valve body 25, making it eccentric to the permeating hole 24a side of the valve seat 26, so as to stop the flow of the fluid. And when the valve is opened, the valve body 25 is rotated 90 deg. to be restored to the original condition. Since the valve body 25 and the rotary shaft 21 are held in the noncontact condition while the valve is operated to open and close in such a way, generation of abrasive powder can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a clean vacuum valve that does not generate foreign matter such as abrasion powder required in semiconductor manufacturing.

[Prior Art] Conventionally, gate valves have been used as vacuum valves for semiconductor manufacturing equipment.

[Problem to be solved by the invention] Conventional gate valves have a structure in which the valve body and the valve seat, or the shaft for vertically moving or rotating the valve body, the bearing, and the casing come into contact with each other during the opening/closing operation. Foreign matter such as abrasion powder generated from this contact area deteriorates the cleanliness of semiconductor manufacturing equipment.
The product yield was reduced.

An object of the present invention is to provide a vacuum valve that prevents the generation of foreign matter such as abrasion powder.

[Means for Solving the Problems] The vacuum valve according to the present invention is formed by a rotary body surface, and consists of two sets of radial magnetic bearings and thrust magnetic bearings, each of which includes a displacement sensor, a phase compensation circuit, a power amplifier, and an electromagnet. A valve body is provided that is supported without contact with the valve seat by a shaft-controlled magnetic bearing.

Preferably, the valve body is rotated by a motor to perform an on-off valve operation.

[Function] In the vacuum valve configured as described above, the 5-axis control magnetic bearing detects the gap between the valve seat and the valve body based on the signal from the displacement sensor, as is well known, and makes sure that the gap is at a predetermined level. The excitation current of the electromagnet is controlled by a phase compensation circuit and a power amplifier so that the

Therefore, the valve element can be rotated by the motor to open and close while floating the valve element above the valve seat in a non-contact manner. Therefore, generation of foreign matter such as abrasion powder due to contact is prevented.

[Example code] The present invention will be described in detail below with reference to the drawings.

In FIG. 1, a rotating body surface, that is, a cylindrical valve body 25, and a rotating shaft 21 formed integrally with the valve body 25 are an electromagnet consisting of a rotating body yoke 4, an electromagnet 3, an electromagnetic excitation coil 5, a displacement Two sets of radial magnetic bearings A, A consisting of a sensor 6, a phase compensation circuit (not shown), and a power amplifier, an electromagnetic thrust disk 10 consisting of an electromagnetic yoke 11, and an excitation coil 12, a thrust position sensor 13, and a phase compensation circuit (not shown). It is magnetically levitated from the valve seat 26 and the casing 20 and supported in a non-contact manner by a five-axis control magnetic bearing including a thrust magnetic bearing B, which includes a circuit and a power amplifier. A rotor 3 of an AC servo motor C is attached to one end of the rotating shaft 21 and a portion of the casing 2o facing thereto.
o and a stator 31 are provided, respectively.

Referring also to FIG. 2, the valve body 25 has a through hole 23 perpendicular to the axis of the rotating shaft 21. As shown in FIG. This through hole 23 is a through hole 24a perpendicular to the axis that communicates both valve flanges 22 and 22 sides of the casing 20 when the valve is opened as shown in the figure.
, 24b. A gasket 27 is provided on one side of the through hole 24a of the valve seat 26.

With this structure, when the valve is opened and when the valve is opened and closed, the five-axis control magnetic bearing consisting of magnetic bearings A, A, and B moves the valve seat 26 based on the signal from the displacement sensor 6.13, as is known.
and the valve body 25 and the gap between the end of the rotating shaft 21 and the casing are detected, and the electromagnet excitation coil 5.
12, the valve body 25 and rotating shaft 21 are magnetically levitated and supported in a non-contact manner with respect to the valve seat 26 and the casing 2o.

When closing the valve, the radial magnetic bearing ASA is controlled to rotate the valve body 26 by 90' as shown in FIG. Stop the flow of indicated fluid.

When the valve is opened, the magnetic bearings A and A are controlled to rotate the valve body 26 by 906 rotations to return it to the valve open position shown in FIG.

Therefore, the valve seat 26 due to the rotation of the valve 26 and the rotating shaft 21
Since there is no contact with the casing 2o, no foreign matter such as abrasion powder is generated.

[Effects of the Invention] Since the present invention is configured as described above, the valve body and the rotating part of the rotating shaft are kept in a non-contact state with respect to the stationary part of the valve seat and the casing during the opening/closing operation of the valve. Generation of foreign matter such as wear particles can be reliably prevented. therefore,
It can provide a clean vacuum valve and improve product yield in semiconductor manufacturing.

Furthermore, since the rotating part and the stationary part can be opened and closed without contact, a relatively small motor can be used and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an embodiment of the present invention, and FIGS. 2 and 3 are X-X in FIG. 1 showing states when the valve is opened and when the valve is closed.
It is a sectional view taken along the line. A... Radial magnetic bearing B... Thrust magnetic bearing C... AC... Servo motor 20... Casing 25... Valve body 26... Valve seat 27...
・Gasket rug figures 2 and 5

Claims (1)

[Claims] A valve body formed of a rotating body surface and supported without contact with the valve seat by a 5-axis control magnetic bearing consisting of two sets of radial magnetic bearings and a thrust magnetic bearing, each consisting of a displacement sensor, a phase compensation circuit, a power amplifier, and an electromagnet. A vacuum valve characterized by being provided with.