Isolation valve for single crystal pulling apparatus

• US 5,356,113 A
• Filed: 09/23/1993
• Issued: 10/18/1994
• Est. Priority Date: 09/30/1992
• Status: Expired due to Fees

• Current Assignee: Shin-Etsu Handotai Co., Ltd. (Shin-Etsu Chemical Company Limited)
• Original Assignee: Shin-Etsu Handotai Co., Ltd. (Shin-Etsu Chemical Company Limited)
• Inventors: Ogino, Katsuhiko, Yokota, Kouzou, Mizuishi, Koji
• Primary Examiner(s): Fox, John C.
• Application Number:
  US08/125,187
• Time in Patent Office: 390 Days
• Field of Search: 251/167, 251/178
• US Class Current: 251/167
• CPC Class Codes: C30B 15/00 Single-crystal growth by pulling from a melt, e.g. Czochralski method under a protective fluid C30B27/00
• CPC Class Codes: F16K 51/02 specially adapted for high-vacuum installations

Abstract

An isolation valve for a single crystal pulling apparatus providing a good sealing performance is disclosed. The apparatus comprises a casing having two opposite valve seats, a first valve seat having a first opening communicable with the main chamber of the apparatus, a second valve seat having a second opening communicable with the pull chamber of the apparatus. The body of the isolation valve includes a first plate movable in and out of contact with the first valve seat to open and shut the first opening, a second plate movable in and out of contact with the second valve seat to open and shut the second opening, and a bellows connecting the first and second plates. The isolation valve also comprises a holder holding the first plate out of contact with the first valve seat when the first plate is opposite to the first valve seat, a passage communicable with a fluid supply and the interior of the valve body, and a controller controlling the pressure of a working fluid supplied from the fluid supply into the interior of the valve body. The controller has a first set pressure at which the first and second plates are in contact with the first and second valve seats and a second set pressure at which the first and second plates are out of contact with the first and second valve seats.

Claims

1. An isolation valve for a single crystal pulling apparatus, the single crystal pulling apparatus having a main chamber in which a crucible holds a melt of a raw material, the single crystal pulling apparatus having a pull chamber which receives a single crystal pulled from the melt, the isolation valve for the single crystal pulling apparatus comprising:

a valve casing having two opposing valve seats, a first valve seat having a first opening communicable with a main chamber, a second valve seat having a second opening communicable with a pull chamber;

a valve rod having a longitudinal axis located within the valve casing, the valve rod being longitudinally movable along the axis and rotatable about the axis;

a valve body rotatably mounted within the valve casing about the longitudinal axis, the valve body including a first plate movable in and out of sealing contact with the first valve seat to open and shut the first opening, a second plate movable in and out of sealing contact with the second valve seat to open and shut the second opening, and a bellows connecting the first plate to the second plate, the first plate being fastened to the valve rod;

a passage communicable with a fluid supply and with an interior of the valve body defined by the first plate, the second plate and the bellows, the passage enabling a working fluid from the fluid supply to pass to the interior of the valve body;

a spring biasing member acting on the valve rod, the biasing member biasing the valve rod axially so that the first plate is out of contact with the first valve seat during rotation of the valve body; and

means, provided intermediate the passage, for controlling the pressure of the interior of the valve body, the controlling means having a first set pressure of the working fluid at which the first plate is in sealing contact with the first valve seat and the second plate is in sealing contact with the second valve seat, the controlling means having a second set pressure of the working fluid at which the first plate is out of sealing contact with the first valve seat and the second plate is out of contact with the second valve seat.

2. The isolation valve for a single crystal pulling apparatus as recited in claim 1, wherein the working fluid is a gas.

3. The isolation valve for a single crystal pulling apparatus as recited in claim 1, wherein the working fluid comprises an inert gas.

4. The isolation valve for a single crystal pulling apparatus as recited in claim 1, wherein the working fluid comprises a liquid coolant.

5. The isolation valve for a single crystal pulling apparatus as recited in claim 1, wherein the passage extends through the first plate.

6. The isolation valve for a single crystal pulling apparatus as recited in claim 1, wherein the first valve seat is located around the first opening, the second valve seat is directly opposed to the first valve seat, the second valve seat supporting the second plate when the second plate is in sealing contact with the second valve seat, and the first plate being uniformly supported against the first valve seat via the working fluid in the interior of the valve body when the first plate is in sealing contact with the first valve seat due to pressure within the bellows and the directly opposed relationship of the first and second valve seats.

7. The isolation valve of claim 1, wherein the passage extends axially through the valve rod and laterally through the first plate.

8. The isolation valve of claim 1, further comprising an air cylinder for driving the rotation of the valve rod.

9. An isolation valve for a single crystal pulling apparatus, the single crystal pulling apparatus having a main chamber in which a crucible holds a melt of a raw material, the single crystal pulling apparatus having a pull chamber which receives a single crystal pulled from the melt, the isolation valve for the single crystal pulling apparatus comprising:

a valve casing having two opposing valve seats, a first valve seat having a first opening communicable with the main chamber and formed around the first opening, a second valve seat having a second opening communicable with the pull chamber and formed around the second opening, the first and second openings being circular and arranged coaxially with each other;

a valve rod having a longitudinal axis located within the valve casing, the valve rod being longitudinally movable along the axis and rotatable about the axis;

a shutter rotatably mounted within the casing about the longitudinal axis, the shutter including a first plate movable in and out of sealing contact with the first valve seat to open and shut the first opening, a second plate movable in and out of sealing contact with the second valve seat to open and shut the second opening, and a bellows connecting the first plate to the second plate, the first plate being fastened to the valve rod;

spring means holding the first plate out of sealing contact with the first valve seat when the first plate is opposite to the first valve seat and the second plate is out of contact with the second valve seat;

a gas passage communicable with a gas supply and with an interior of the shutter defined by the first plate, the second plate and the bellows, the gas passage enabling a working gas from the gas supply to pass to the interior of the shutter; and

means, provided intermediate the gas passage, for controlling the pressure of the interior of the shutter, the controlling means having a first set pressure of the gas at which the first plate is in sealing contact with the first valve seat and the second plate is in sealing contact with the second valve seat, the controlling means having a second set pressure of the gas at which the first plate is out of sealing contact with the first valve seal and the second plate is out of contact with the second valve seat.

10. The isolation valve of claim 9, wherein the passage extends axially through the valve rod and laterally through the first plate.

11. The isolation valve of claim 9, further comprising an air cylinder for driving the rotation of the valve rod.