Fluid handling – With cleaner – lubrication added to fluid or liquid sealing... – Cleaning or steam sterilizing
Reexamination Certificate
2000-03-27
2001-03-27
Fox, John (Department: 3753)
Fluid handling
With cleaner, lubrication added to fluid or liquid sealing...
Cleaning or steam sterilizing
C222S148000
Reexamination Certificate
active
06206026
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a valve for a gas cylinder (gas cylinder valve), more specifically to a gas cylinder valve having a structure suitable for a gas cylinder supplying a high-purity gas such as semiconductor material gases, purge gases and carrier gases, employed in the process for manufacturing electronic devices in semiconductor industries.
BACKGROUND ART
High purity and cleanness is required in those semiconductor material gases, purge gases, carrier gases, etc. which are employed in the semiconductor manufacturing process. Presence of contaminant such as particles, oxygen and moisture if any in these gases causes problems such as insufficient device characteristics attributed to oxidation or metal pollution and reduction in the yield of products.
Generally, when a gas cylinder valve is set to a plant for supplying or producing a semiconductor process gas, the atmospheric air migrates between a mouth ring (or port) of the valve and a pipe for fitting to such a plant, since the port of the gas cylinder valve is exposed to the atmospheric air. The thus migrated atmospheric air is removed by purging with an inert gas such as a nitrogen gas and an argon gas or by evacuation. However, if the migrated contaminant is removed insufficiently, residual contaminant migrates into the gas cylinder during manufacture of a gas. For example, in the case of a gas having reactivity with the atmospheric component gases such as oxygen and water, these gases are causative of change in the concentration of the product gas with time, oxidation reactions to form impurity products and corrosion on the metal surfaces of the gas cylinder and the gas cylinder valve to be brought into contact with the gas.
Further, in supplying a gas, contamination with the residual impurity contents occurs from the gas supply plant to a gas consuming plant. The influence of contamination during the supply of the gas appears not only in the gas system but also as reduction in the yield of products and deterioration in the electric characteristics.
Gas cylinder valves employed conventionally most frequently are of the single-ported structure in which one port serves both as a gas outlet port and a gas inlet port, and the valves contain dead spaces, so that it takes much time for removing the atmospheric air components migrated into the gas cylinder valves when they are attached to gas cylinders.
Meanwhile, gas cylinder valves are proposed as described in Japanese Unexamined Patent Publication Nos. 106749/1993 and 281026/1994 so as to overcome the above problem. Although these valves can remove contaminant contained therein quickly, they involve problems in terms of safety in that the valves themselves have very large dimensions due to the block valve structure having two gas cylinder valves integrated into one block causing gas cylinders having such valves to tumble easily during transportation. These gas cylinder valves involve further problems in that the cost increases on a wide margin due to their intricate structures compared with the ordinary cylinder valves and that an extra piping for a purge gas must be provided for the gas plant side. While there is also known a gas cylinder valve incorporated with a purge valve, this gas cylinder valve has an intricate valve structure and a relatively large size and is also expensive.
DISCLOSURE OF THE INVENTION
It is an objective of the present invention to provide a gas cylinder valve which can remove particles and atmospheric air components migrated thereto quickly and efficiently when a pipe for connecting to a gas plant is connected to the valve, causes no reduction in the conductance at the time of evacuation, has a simple structure capable of achieving downsizing, and can be manufactured inexpensively.
The gas cylinder valve according to the present invention is provided with a valve body having a valve chamber containing a valving element which opens and closes an annular valve seat, and a gas cylinder plugging end portion and a pipe-connecting port both formed on the valve body; wherein the gas cylinder plugging end portion contains an upstream side gas channel opening at one extremity to an end thereof and at the other extremity to an internal circumference of the valve seat; the port contains two downstream side gas channels each opening at one extremity to an end thereof and at the other extremity to an external circumference of the valve seat; a metal connector containing two channels to be connected to the two downstream side gas channels respectively is fitted in the port; one of two channels is connected to a purge gas charge side, while the other channel is connected to a purge gas bleed side.
Meanwhile, valve chamber openings of the two downstream side gas channels are positioned to be spaced farthest from each other in the valve chamber. Further, the valve chamber is formed concentrically with respect to a valve chamber opening of the upstream side gas channel so as to surround the valve seat, while the valve chamber openings of the two downstream side gas channels are located to oppose each other across the valve seat.
The gas cylinder valve according to the present invention can give sufficient purge characteristics in spite of its simple structure. Besides, the gas cylinder valve of the present invention is the same as the conventional single-ported gas cylinder valve in terms of shape and can be manufactured in the same manner, so that it can be attached readily to the existing gas manufacture plants and gas supply plants.
REFERENCES:
patent: 5232019 (1993-08-01), Wolff et al.
patent: 5738145 (1998-04-01), Daicho et al.
patent: 3-93662 (1991-09-01), None
patent: 5-106749 (1993-04-01), None
patent: 5-50249 (1994-07-01), None
patent: 6-281026 (1994-10-01), None
patent: 8-5000 (1996-01-01), None
Hasaka Satoshi
Hasegawa Hideharu
Ikeda Takuya
Isaki Ryuichiro
Armstrong, Westerman Hattori, McLeland & Naughton, L.L.P.
Fox John
Nippon Sanso Corporation
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