Dispensing – With discharge assistant – Fluid pressure
Reexamination Certificate
2003-05-06
2004-11-23
Kaufman, Joseph A. (Department: 3754)
Dispensing
With discharge assistant
Fluid pressure
C222S402200
Reexamination Certificate
active
06820778
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a gas spray valve for spraying contents of a gas container with the help of high-pressure gas as a propellant, such as liquid carbon dioxide, and more particularly, to an improved gas spray valve that permits reuse of gas containers.
BACKGROUND ART
One type of spray apparatus has traditionally been used that operates by spraying the contents of a gas container, such as a medical agent, with the help of high-pressure gas loaded in the container together with the contents. In such spray apparatuses, the gas is sprayed through a gas spray valve secured to an opening portion of the gas container. These spray apparatuses use certain types of chlorofluorocarbons as the propellant. In view of recent concerns about environmental protection, however, newly developed spray apparatuses that make use of HFC-134a, an alternative to chlorofluorocarbon, are becoming increasingly common in the marketplace.
Although HFC-134a has substantially no effects on the ozone layer, it has a significant impact on the global warming, 1000 times more significant than the impact of CO
2
, or even worse. Therefore, a future increase in the use of HFC-134a is expected to pose a new problem. For this reason, it is proposed to use other propellants for spray apparatuses that have less effects on the ozone layer destruction or global warming, including carbon dioxide, gaseous nitrogen, and inert gases such as helium, neon, krypton, xenon, and radon.
It is desired that these gases, as with the hydrofluorocarbons currently in use, be liquefied when used as a propellant for use in spray apparatuses in order to make the gas container small. For example, liquid carbon dioxide has a vapor pressure of 60 kgf/cm
2
at 20° C. It is also preferred in terms of volume efficiency that the inert gases also be highly pressurized or liquefied and thus be put under a pressure of 50 kgf/cm
2
or greater.
Handling such high-pressure gases requires a specially designed gas spray valve, such as the one described in Japanese Patent Laid-Open Publication No. Hei 8-141450.
As shown in
FIG. 7
, this gas spray valve includes a valve case
2
secured to an opening portion la of a gas container
1
and a valve pin
3
slidably received in the valve case
2
. A first seal ring
4
and a second seal ring
5
are arranged within the valve case
2
and are axially spaced apart from each other. A metering chamber
6
is formed between the seal rings
4
and
5
for trapping a predetermined amount of the gas prior to spraying. The valve pin
3
includes on the lower end thereof a first valve portion
7
that comes into close contact with the first seal ring
4
when the valve pin
3
is pushed in from the outside. The valve pin
3
also includes on the upper end thereof a second valve portion
8
. The second valve portion
8
consists of a portion with larger diameter
8
a
that comes into close contact with the second seal ring
5
when the valve pin
3
is in its upper position and a portion with smaller diameter
8
b
that defines a gap together with the second seal ring
5
when the valve pin
3
has been pushed in from the outside. The metering chamber accommodates a spring
9
, which always urges the valve pin
3
upward.
When the gas spray valve constructed in the above-described manner is in its steady state without the valve pin
3
being pushed from the outside, the first valve portion
7
is apart from the first seal ring
4
with the large portion
8
a
of the second valve portion
8
remaining in close contact with the second seal ring
5
, such that the interior of the gas container
1
remains in communication with the metering chamber
6
. As the valve pin
3
is pushed in from the outside, the first valve portion
7
comes into close contact with the first seal ring
4
, followed by formation of a gap between the small portion
8
b
of the second valve portion
8
and the second seal ring
5
. The gap allows the contents of the gas container
1
to pass through along with the gas. The contents and the gas are then sprayed out from the gas container
1
. Since formation of the gap between the second valve portion
8
and the second seal ring
5
is immediately preceded by the first valve portion
7
coming into close contact with the first seal ring
4
to close communication between the metering chamber
6
and the interior of the gas chamber
1
, a predetermined amount of the mixture of the gas and the contents trapped in the metering chamber
6
is sprayed from the gas spray valve.
A construction of gas spray valve that permits reuse of the gas container and the gas spray valve is described in Japanese Patent Laid-Open Publication No. Hei 11-301759. As shown in
FIG. 8
, the gas spray valve
10
includes a valve case
12
secured to an opening portion
11
a
of a gas container
11
and a valve pin
13
slidably received in the valve case
12
. Arranged within the valve case
12
are a first seal ring
18
, which comes into close contact with the outer surface of the valve pin
13
at a first position relatively close to the center of the gas container
11
, and a second seal ring
19
, which comes into close contact with the outer surface of the valve pin
13
at a second position relatively far from the center of the gas container
11
. A metering chamber
21
is defined within the valve case
12
between the first seal ring
18
and the second seal ring
19
for trapping a predetermined amount of gas prior to spraying. The valve pin
13
includes a gas conduit
22
, which extends through the valve pin
13
from the top end thereof positioned outside the gas container
11
and opens in the outer periphery of the valve pin
13
at a position axially apart from the top end. The opening of the gas conduit
22
on the outer periphery of the valve pin
13
is arranged such that it is positioned above the second seal ring
19
when the valve pin
13
is in its raised position and it is positioned below the second seal ring
19
within the metering chamber
21
when the valve pin
13
is pushed down to a first stop position or further to a second stop position at which the valve pin stops during its two-step action. The valve pin
13
further includes a first bypass portion and a second bypass portion that, together with the inner surface of the first seal ring
18
, form a gap when the valve pin
13
is in the raised position and in the second stop position, respectively, so that the interior of the gas container
11
communicates with the metering chamber
21
through this gap.
When the valve pin
13
is in the raised position in the gas spray valve of the above-described construction, the opening of the gas conduit
22
on the outer periphery of the valve pin
13
is positioned above the second seal ring
19
. As a result, communication between the gas conduit
22
and the metering chamber
21
is closed, whereas the metering chamber
21
remains in communication with the interior of the gas container
11
through the first bypass portion of the valve pin
13
. When the valve pin
13
is pushed into the first stop position, the first seal ring
18
closes communication between the gas container
11
and the metering chamber
21
, and the opening of the gas conduit
22
on the outer periphery of the valve pin
13
is positioned within the metering chamber
21
. As a result, the predetermined amount of the gas trapped in the metering chamber
21
is sprayed out from the gas container
11
through the gas conduit
22
. When it is desired to injector refill the gas into the gas container
11
, a gas injector is connected to the valve pin
13
and the valve pin
13
is pushed into the second stop position. This causes the opening of the gas conduit
22
on the outer periphery of the valve pin
13
to move into the metering chamber
21
and brings the metering chamber
21
into communication with the interior of the gas container
11
through the second bypass portion of the valve pin
13
. As a result, the gas is injected from the gas injector, through the metering chamber
21
and t
Bio Actis Limited
Crowell & Moring LLP
Kaufman Joseph A.
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