Integration of Automated Cryopump Safety Purge

• US 20090007574A1
• Filed: 07/22/2008
• Published: 01/08/2009
• Est. Priority Date: 06/27/2003
• Status: Active Grant

• Current Assignee: Edwards Vacuum, LLC (Atlas Copco AB)
• Original Assignee: Brooks Automation Incorporated (Azenta, Inc.)
• Inventors: Buonpane, Maureen C., Amundsen, Paul E., Jacobs, Jordan, Andrews, Douglas
• Granted Patent: US 9,970,427 B2
• Time in Patent Office: Days
• US Class Current: 62/55.500
• CPC Class Codes: F04B 37/08 by condensing or freezing, e.g. cryogenic pumps
• CPC Class Codes: F04B 37/085 Regeneration of cryo-pumps
• CPC Class Codes: F04B 49/065 and making use of computers

Abstract

A system and method is provided to control a purge valve during an unsafe condition associated with a cryopump. An electronic controller may be used to control the opening and closing of one or more purge valves during the unsafe condition. The purge valve can be a cryo-purge valve or exhaust purge valve. The purge valve can be a normally open valve. The electronic controller can release the normally open valve in response to the unsafe condition. The electronic controller can delay its response to the unsafe condition for a safe period of time. Attempts from other systems to control these valves during unsafe conditions can be preempted during unsafe conditions. A user can be inhibited from manually controlling the purge valve during unsafe conditions. A power failure recovery routine may be initiated in response to a restoration of power. The power failure recovery routine can respond to an unsafe condition even if the power failure recovery routine has been manually turned off by a user.

Claims

1. A method of controlling a cryopump, the method comprising:

responding to a potentially unsafe condition in the cryopump by retaining a normally open purge valve closed for a period of time; and

after the period of time elapses, allowing the purge valve to open to emit a purge gas into the cryopump.

2. A method according to claim 1 wherein the purge valve is a cryo-purge valve coupled to the cryopump.

3. A method according to claim 1 wherein the purge valve is an exhaust purge valve coupled to an exhaust line of the cryopump.

4. A method according to claim 1 wherein a potentially unsafe condition exists when there is any one of:

a power failure of the cryopump;

a temperature of the cryopump greater than a temperature threshold;

or an inability to determine a temperature of the cryopump.

5. A method according to claim 4 wherein if the unsafe condition is a power failure and the power is restored, responding to the restored power by initiating a power failure recovery routine.

6. A method according to claim 5 wherein the power failure recovery routine includes determining an operating state of the cryopump by determining whether the cryopump was in a regeneration process when the power failed.

7. A method according to claim 6 wherein the power failure recovery routine responds to a determination that the cryopump was not in a regeneration process at the time of power failure by:

determining that a temperature of the cryopump is less than a temperature threshold; and

responding to the determination that the temperature is less than the temperature threshold by allowing the host controller to have control of the purge valve.

8. A method according to claim 6 wherein the power failure recovery routine responds to a determination that the cryopump was not in a regeneration process at the time of power failure by:

determining that a temperature of the cryopump is above a temperature threshold; and

responding to the determination that the temperature is above the temperature threshold by directing a purge valve to open and assuring that the purge valve remains open for a period of time.

9. A method according to claim 6 wherein the power failure recovery routine responds a determination that the cryopump was in a regeneration process at the time of power failure by:

determining that the cryopump was cooling down at the time of power failure; and

continuing the cooling.

10. A method according to claim 6 wherein the power failure recovery routine responds to a determination that the cryopump was in a regeneration process by initiating a regeneration process.

11. A method according to claim 6 wherein the power failure recovery routine further includes:

determining that a temperature sensor is not operating; and

responding to the temperature sensor not operating by directing a purge valve to open and assuring that the purge valve remains open for a period of time.

12. A method according to claim 5 wherein the power failure recovery routine cannot be aborted.

13. A method according to claim 5 wherein the power failure recovery routine is initiated after every power failure.

14. A method according to claim 13 wherein initiating the power failure recovery routine after every power failure further includes responding to the restored power by initiating the power failure recovery routine regardless of whether the power failure recovery routine is turned off.

15. A method according to claim 1 wherein the period of time is two minutes.

16. A method according to claim 1 wherein the response to the unsafe condition further includes preventing a user from manually closing the purge valve.

17. A cryopump control system comprising:

an electronic controller that responds to an unsafe condition associated with a cryopump by;

responding to a potentially unsafe condition in the cryopump by retaining a normally open purge valve closed for a period of time; and

after the period of time elapses, allowing the purge valve to open to emit a purge gas into the cryopump.

18. A cryopump control system according to claim 17 wherein the purge valve is a cryo-purge valve.

19. A cryopump control system according to claim 17 wherein the purge valve is an exhaust purge valve coupled to an exhaust line.

20. A system for controlling a cryopump comprising:

means for responding to a potentially unsafe condition in the cryopump by retaining a normally open purge valve closed for a period of time; and

means for allowing, after the period of time elapses, the purge valve to open to emit a purge gas into the cryopump.