Fluid handling – Systems – Sequentially progressive opening or closing of plural valves
Reexamination Certificate
1999-09-22
2001-09-18
Rivell, John (Department: 3753)
Fluid handling
Systems
Sequentially progressive opening or closing of plural valves
C137S630000
Reexamination Certificate
active
06289932
ABSTRACT:
FIELD OF THE INVENTION
The following invention relates to valves which have multiple ports for communication of fluids between a common inlet and a common outlet. More particularly, this invention relates to valves used particularly in ultra high vacuum conditions which include a smaller “soft start” port and a larger “main” port so that pressure can be equalized on opposite sides of the valve initially through the soft start port before the main port is opened between the inlet and the outlet.
BACKGROUND OF THE INVENTION
Ultra high vacuum handling equipment such as that used in semiconductor processing and other ultra high vacuum environments typically have valves appropriately located therein to control flow of gases through the equipment. Such ultra high vacuum equipment valves can have a variety of different configurations but are often configured as poppet valves which can be actuated in a variety of different ways to provide access between an inlet and an outlet of the valve.
Often a pressure of the gases on either side of the valve are somewhat different before the valve is opened. When the valve is initially opened a rush of gas through the valve occurs to equalize pressure on either side of the valve. This rush of air to equalize pressure through the valve can be undesirable in many circumstances. For instance, in semiconductor device manufacturing equipment, it is important that contaminants be eliminated from regions where manufacturing processes are occurring. When a rush of air occurs through a valve that is opening, particles which had previously settled to inside surfaces of the vacuum handling equipment can be stirred up into a free floating state and then land on devices being processed, causing damage.
One known technique for eliminating an initial rush of air through an opening valve and the related negative consequences is to utilize a valve having a “soft start” feature. Soft start valves include two ports/pathways passing between a single common inlet of the valve and a single common outlet of the valve. The first soft start port is significantly smaller in size than a second “main” port. When the valve is to be opened, the soft start port is opened first so that pressure can be equalized through a small soft start passage. This smaller passage is sufficiently small that pressure is balanced between the inlet and the outlet of the valve without stirring up particulates which may be resting on either side of the valve. After pressure has been equalized through the soft start passage, the main port is opened to provide full communication between the inlet and the outlet of the valve.
Known prior art valves which include such a soft start feature include the “Series 62” angle valve with soft start function provided by VAT, Inc. of Woburn, Mass.; the “VacuComp” series 150/160 valve by MKS Instruments, Inc. of Boulder Colo.; and the “XLD” vacuum soft start valves by SMC Pneumatics, Inc. of Indianapolis, Ind. While these known prior art “soft start” valves are generally effective, they suffer from being unnecessarily complex and including substantially separate activation systems for the two ports, resulting in valves which are difficult to manufacture and which are not as easily maintained in proper working order. Such drawbacks are particularly magnified in semiconductor processing equipment where automated processes require repetitive opening and closing of the valves over long periods of time.
Accordingly, a need exists for a “soft start” valve which has a simpler design and which has fewer moving parts so that a valve capable of longer life, greater reliability and simpler manufacture is provided.
SUMMARY OF THE INVENTION
This invention provides a “soft start” valve which has both a “soft start” port/pathway and a main port/pathway opened by movement of a single piston within a single pneumatic cylinder. The soft start port is preferably located within a main poppet with a soft start shaft coaxially passing through a shaft bore within a main shaft. The soft start shaft is coupled directly to the piston so that when the piston moves down, the soft start shaft moves down relative to the main shaft and the soft start poppet moves down below the main poppet to open the soft start port. A soft start return spring and a main spring bias the piston at a middle position within the pneumatic cylinder. When the piston is moved upward within the pneumatic cylinder, the soft start shaft and soft start poppet move up with the piston and lift the main poppet and main shaft upward along with the piston.
Separate air (or other actuation fluid) ports lead to regions within the pneumatic cylinder above and below the piston so that the piston can be driven in the direction desired for either soft start function of the valve or main function of the valve. A single bellows preferably extends up from the main poppet. The main spring biases the main poppet in a closed position down against the body of the valve surrounding the outlet bore of the body. The single dual acting piston simplifies the method by which the valve is caused to act in either the soft start mode or the main mode, simplifying the overall valve actuation mechanism of this invention.
OBJECTS OF THE INVENTION
Accordingly, a primary object of the invention to provide a valve which has both a soft start port and a main port each passing between a common inlet and a common outlet of the valve, with the soft start port sufficiently small to prevent significant turbulence from being generated when the soft start port of the valve is opened and a pressure differential exists across the valve.
Another object of the present invention is to provide a valve with a soft start port which is capable of reliable operation over numerous cycles.
Another object of the present invention is to provide a soft start valve which is pneumatically actuated and has a separate air port for actuating the soft start portion of the valve and a separate air port for actuating the main portion of the valve.
Another object of the present invention is to provide a soft start valve which can be readily manufactured.
Another object of the present invention is to provide a soft start valve which is suitable for use in ultra high vacuum applications.
In addition to the above objects, various other objects of this invention will be apparent from a careful reading of this specification including the detailed description contained herein below.
REFERENCES:
patent: 1882392 (1932-10-01), Musgrave
patent: 3078875 (1963-02-01), Farrell et al.
patent: 3190314 (1965-06-01), Visos et al.
patent: 3211419 (1965-10-01), Klinger-Lohr
patent: 3563274 (1971-02-01), Tischler
patent: 3631894 (1972-01-01), Frantz
patent: 3881459 (1975-05-01), Gaetcke
patent: 4041979 (1977-08-01), Grotloh
patent: 4342328 (1982-08-01), Matta
patent: 4672203 (1987-06-01), Holkerboer
patent: 5172722 (1992-12-01), Nishimura
patent: 5492150 (1996-02-01), Aquilino
patent: 5618086 (1997-04-01), Reuter
patent: 5848608 (1998-12-01), Ishigaki
Chell Instruments, Ltd., Vacuum Isolation and Soft-Start Valves for Critical Applications, advertisement.
HPS Division, MKS Instruments, Inc., High Vacuum Bellows Sealed Valves, catalog, Jul. 1994.
Vat, Angle Valve with Soft-Pump Function, catalog.
Nilsson Tim E.
Rosenbaum, Jr. Preston C.
Thackeray Christopher G.
Heisler & Associates
Nor-Cal Products, Inc.
Rivell John
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