Note: Descriptions are shown in the official language in which they were submitted.
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VALVE FOR PUNCTURING AND RELEASING GAS
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FROM A PRESSURIZED CYLINDER
BACKGROUND OF THE INVENTION
Thls invention relates to valves for puncturing
and releasing gas from pressurizecl cylinders.
Numerous configurations for valves of this type
are known. U.S. Patents Nos. 805,474, 1,782,020,
1,826,088, 2,028,651 2,634,754, 3,070,818, 3,633,596,
3,938,704 and 4,463,929 illus~rate some of -the
designs which have been proposed.
Although many prior ar~ valves work successfully
with low pressure cylinders, e.g., cylinders whose
internal pressures are on the order of 800 pounds per
square inch (psi), such valves are generally not
adaptable for use with high pressure cylinders, e.g.,
cylinders whose internal pressures are on the order
of 6,000 psi. Specifically, it takes more force to
break the seal on a high pressure cylinder than it
does on a low pressure cylinder. Accordingly, it has
generally been found difficult to break these seals
with existing low pressure puncturing mechanisms and,
in particular, with manually-operated mechanisms,
including manually-operated mechanisms employing cams
and springs to aid the user in puncturing the seal.
Moreover, the breaking of the seal on a high
pressure c~ylirlder produces an exiting stream of high
pressure gas. This escaping gas represents an
additional force which the puncturing mechanism mttst
overcome to open the cylinder. In general, it has
been found difficult to generate enough inward force
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to quickly and reliably open the seal on high
pressure cylinders in the presence of escaping gas
with existing low pressure puncturing mechanisms and,
in particular, manually-operated mechanisms.
High pressure cylinders filled with nitrogen or
air and employing poppet type valves have been used
to inflate life rafts. However, because of the
problems discussed above, cylinders employing
puncture type seals and, in particular, hermetically
sealed cylinders, have not been used with these gases
at high pressures. Rather, these types of seals have
been limited to low pressure cylinders employing
carbon dioxide as the primary inflation gas. As is
recognized in the art, puncture type seals and, in
particular, puncture type seals in which the cylinder
is hermetically sealed, are preferred to poppet type
seals because of the reduced chance of significant
loss of pressure during storage.
The inflation of life rafts would bene~it from
the availability of a reliable valve for high
pressure cylinders employing puncture type seals
since this would mean that these cylinders could be
used when nitrogen or air, instead of carbon dioxide,
is to be the primary infl~tion gas. Although carbon
dioxide is a suitable gas for inflating life rafts at
normal temperatures, problems develop when either low
or high temperatures are encountered, e.g., low
temperatures on the order of -30F or high
temperatures on the order of -~150F. Such
temperatures can be encountered for life rafts used
in aircraft, especially wh~n the life raft is stored
in the aircraft's wings.
At low temperatures, the liquid carbon dioxide
in the cylinder vaporizes slowly resulting in a slow
inflation process. Moreover, the expansion of the
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carbon dioxide vapor as it passes out o~ the cylinder
into the life raft results in even lower temperatures
which causes the carbon dioxide vapor to soli~i~y
into dry ice. The dry ice, in turn, can block the
exi-t passages in the valve, thus furt~er slowing the
inflation process, and can accumulate on and thus
damage the fabric making up the life raft. At high
temperatures, on the other hand, the pressure in the
cylinder can increase to levels characteristic of a
high pressure cylinder thus bringing into play the
problems, discussed above7 which arise in puncturing
high pressure cylinders.
In contrast, nitrogen and air do not exhibit
temperature dependent problems over the -30F to
-~150F range, or, for that matter, even substantially
beyond that range. Indeed, charges of nitrogen have
been included in carbon dioxide cylinders to help
propel liquid carbon dioxide out of the cylinder
under low temperature conditions. However, to
provide the same number of cubic feet of gas at one
atmosphere pressure from Q cylinder filled with
nitrogen or air as are provided by a cylinder filled
with liquid carbon dioxide, pressures on the order of
6000 psi must be employed. To date, notwithstanding
their superior properties in comparison to carbon
dioxide, this need for higher pressures and the
resulting need for a reliable valve capable of
puncturing high pressure cylinders have prevented the
use of puncture-type nitrogen or air cylinders in the
inflation of life rafts.
SUMMARY OF THE INVENTION
In accordance with one of its aspects, the
invention provides a valve mechanism ~or opening the
seal on the mouth of a pressurized cylinder which
comprises:
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(A) a valve body which has a longitu~inal axis;
(B) means for attaching the valve body to the
cylinder so that tl~e longitudinal axis intersects the
cylinder's mouth;
(C) a chamber within the valve body;
(D) a piston assernbly journaled in the ~ody for
movement along the longl-tudinal axis, the piston
assembly including:
(1) a piston which divides the chamber
into two portions, one portion being towards the
cylinder's mollth and the other portion being away
from the mouth, the por-tion towards the mouth being
(a) vented and (b) isolated from the mouth so that
gas cannot pass from the mouth to this portion of the
chamber; and
(2) means which moves with the piston for
opening the seal;
(E) m~ans for conducting gas from the mouth of
the cylinder to the portion of the chamber away from
the mouth; and
(F) means for moving the piston assembly along
the longitudinal axis towards the mouth of the
cylinder so as to open the cylinder's seal, the
escaping gas from the cylinder's mouth being
conducted to the portion of the cham~er away from the
mouth where it ~orces the piston towards the mouth,
thus aiding the moving means in completing the
opening process.
In accordance with another aspect of the
invention, there is provlded apparatus for opening
the seal on the mouth of a cylinder which contains
pressurized gas comprising:
(a) a body having an axis and including a
chamber;
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(b) means for attaching the body to the
cylinder in the region of the mouth 90 that the axis
intersects the mouth;
(c) a piston assembly journaled in the body for
movement along the axis, the piston assembly
including:
(i) a piston which divides the chamber
into a portion away from the mouth and a portion
towards the mouth, the portion towards the mouth
being isolated from the mouth; and
(ii) means which moves with the piston for
opening the seal;
(d) means ~or conducting gas from the mouth to
the portion of the chamber away from the mouth;
(e) means for venting the portion of the
chamber towards the mouth; and
(f) means for moving the piston assembly along
the axis towards the mouth for a limited portion of
the total stroke of the piston through the chamber so
that the means for opening produces an initial
opening of the sPal, the gas escaping from the mouth
through the opening being conducted to the portion of
the chamber away from the mouth by the conducting
means where it moves the piston assembly towards the
mouth for the remainder of the total stroke of the
piston to produce a complete opening of the seal.
In certain preferred embodiments of the
invention, the valve includes an exit conduit which
is connected to the portion of the chamber towards
the cylinder's mouth, i.e., the vented portion of the
chamber, when the valve is not in use and which
becomes connected to the portion of the chamber away
from the cylinder's mouth as the valve is used so
that the pressure of the gas exiting from the
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cylinder is contlnually applied to the piston
assembly to hold that assembly in its fully operated
position until all the gas has escaped from the
cylinder.
In other preferred embodiments, the means for
conducting gas from the cylinder's mouth to the
portion of the chamber away from the cylinder's mouth
is ven-tecl to the outside of -the valve body when the
valve is not in use so as to provide an escape path
for the gas in the cylinder if the seal on the
cylinder should rupture ei-ther accidently or as the
result of a build up of excess pressure in the
cylinder due to, for example, heating of the
cylinder.
In still other pre~erred embo~iments, the means
for conducting gas from the cylinder's mouth to the
portion of the chamber away from the cylinder's mouth
comprises a conduit which passes through the piston.
In connection with these embodiments, it is ~urther
preferred to use the leading edge of the conduit as
the means for opening the seal and to vent the
trailing portion of the conduit to provide the escape
path for the gas in the cylinder in the case of a
seal rupture when the valve is not in use.
The accompanying drawings, which are
incorporated in and constitute part of the
specification, illustrate the preferred embodiments
of the invention, and together with the description,
serve to explain the principles of the invention. As
used in this specification and in the appended
clai~s, the word "cylinder" is in-tended to
generically encompass vessels and containers for
holding pressurized gas of all sizes and shapes and
not merely those which are cylindrically shaped.
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BRIEF DESCRIPTION OF THE DR~WINGS
Figure 1 is a perspective view o~ a gas cylinder
to which has been attached a valve constructed in
accordance wi-th the presen~ invention.
Figure 2 is a side view showing the valve and
the top portion of the cylinder of Figure 1.
Figure 3 is a cross-sectional view along lines
3-3 in Figure 2 showing the actuation mechanism of
the valve in its inactive/ready state.
Figure 4 is a cross-sectional view along lines
4-4 in Figure 3 showing the valve in its
inactive/ready state.
Figure 5 is a cross-sectional view along lines
5-5 in Figure 4 showing the valve in its
inactive/ready state.
Figure 6 is a cross-sectional view along lines
4-4 in Figure 3 showing the valve after initial
opening of the seal on the cylinder.
Figure 7 is an exploded perspective view o the
components of the valve.
Figure 8 is a cross-sectional view ~long lines
4-4 in Figure 3 showing -the valve in its fully
activated state.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference now to the drawings, wherein like
reference characters designate like or corresponding
parts throughou-t the several views, there is shown in
Figure 1 a perspective view of a pressurized cylinder
10 to which has been attached valve 13 constructed in
accordance with the present invention.
Valve 13 is attached to cylinder 10 by means of
thread 18 which mates with complementary thread 19
formed around the outside of the eylinder's mouth 16.
When attached to the cylinder, the valve's
longitudinal axis 20 intersects mouth 16, and, in
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particular, intersects seal 22 which is formed in the
mouth and seals the cylinder closed.
Valve 13 includes body 14 within which are
cha~lber 24 and piston assembly 26. Piston assembly
26 includes: a) cutter 28 having an opening 25 and a
sharp, leading edge 29 which is used to puncture seal
22, b) piston 30 which rides in chamber 24, and c)
e~tension 32 which journals the piston assembly in
body 14 along longi-tudinal axis 20. O-rings 44 and
46 are used to form seals between valve body 14 and
piston 30 and extension 32, respectively.
Formed within cutter 28, piston 30, and
extension 32 is condui-t 48 which conducts the exiting
gas (indicated by arrows 50 in Figures 6 and 8~ from
mouth 16 into the valve. The exiting gas leaves
conduit 48 by means of crossed-ports 52 formed in the
trailing portion of the conduit. When the valve is
not in use, ports 52 are connected to vent passag~s
54 which pass through and out of valve body 14 (see
Figure 5). The conduit~port/vent pathway provides an
escape route for the pressurized gases in cylinder 10
if the cylinder's seal 22 should unegpectedly rup~ure
during storage or handling.
Connected to chamber 24 is exit conduit 56,
attached to which by means of threads 60 :is outlet
assembly 58. This assembly includes threaded nut 62
for attaching the valve to a life raft or other
device to which the pressurized gas in cylinder 10 is
to be applied. Nut 62 is mounted on nut retainer 63
which is threaded into threads 60. As shown in the
figures, diffuser 64 having exit ports 66 has been
threaded into nut 62. Diffuser 64 allows the gas in
cylinder 10 to safely leave valve 13 if the valve is
acciclently operated during shipping or handling.
0-ring 68 is used to ~orm a seal between outlet
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assembly 58 and valve body 14. During shipping,
O-ring 70 is used to form a seal between di~fuser 64
and the outlet assembly. During use, O-ring 70
provides a seal between the outlet assembly and, for
example, the raft inlet.
Piston 30 divides chamber 24 into a portion 34
towards mouth 16 and a portion 36 away from mouth 16.
Seal plate 38 forms the bottom of chamber 24. This
plate and its associated 0-rings 40 and 42 isolate
portion 34 of chamber 24 from mouth 16 so that the
exiting gases from cylinder 10 cannot reach this
portion of the chamber. As can best be seen in
Figures 5 and 7, the upper surface of seal plate 38
includes channels 72 which connect portion 34 of
chamber 24 to vent passages 74 which pass through and
out of valve body 14.
As discussed below, as the valve is used9 piston
30 moves downward causing the size of portion 34 of
chamber 24 to decrease to essentially zero volume and
the size of portion 36 to increase until it comprises
essentially the total volume of chamber 24 not
occupied by the piston assembly (see Figures 4-6 and
8). Channels 72 in seal plate 38 and vent passages
74 allow the air in portion 34 to exit from the valve
during this downward movement of the piston.
As can be seen by comparing Figures 4, 6 and 8,
exit conduit 56 is connected to portion 34 oE chamber
24 when the valve is not in use and becomes connected
to portion 36 as the valve i9 used. The connection
to portion 34 when the valve is not in use results in
the exit conduit, and thus whatever device is
connected to the exit conduit, being vented to
atmospheric pressure by means of channels 72 and vent
passages 74. Such venting is of particular value in
connection with the inflation of life rafts since it
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provides a~ exit path for any air which may be
present in the li~e ra~t. For li~e rafts carried in
aircra~t, an exit path for such residual air is
necessary to avoid par~ial inflation o~ the life raft
as the altitude of the aircraft increases.
To hold piston assembly 26 in its inac-tive/ready
position, valve 13 includes detent mechanism 84.
This mechanlsm includes ball 76, spring 78, and set
screw 80. Ball 76 engages groove 82 ~ormed in the
upper portion of extension 32 and thus holds the
piston assembly in its uppermost position with cutter
28 out of engagement with seal 22.
Valve 13 is activated by means of actuator
assembly 86. This assembly comprises actuator 88,
actuator housing 90, bushing 92, detent clip 9~, pin
96, lanyard 98, and lanyard ball 100. The actuator
assembly is held in place by means of cover 102 which
includes pins 104 which pass through actuator housing
90 into valve body 14. The cover, in turn, is held
in place by screws 106 which pass through the
actuator housing and engage threaded ~oles 10~ in
valve body 14.
Actuator assembly 86 works as ~ollows. Lanyard
98 and lanyard ball 100 pass through opening 110 in
actuator housing 90 and are wrapped around actuator
88 with the lanyard being received in groove 112 and
the ball in recess 11~. In the assembled valve, the
actuator rides in actuator housing 90 and is
journaled on pin 96. Bushing 92 surrounds eccentric
portion 116 o~ the actuator and serves to reduce
~riction between the ac-tuator and the upper surface
o~ extension 32 o~ piston assembly 26. Detent clip
94 engages the edge of recess 11~ and holds the
actuator assembly in its inactive/ready condition.
131 1 17~
Pulllng on lanyard 98 causes actuator 88 to
rotate approximately 180. Eccentric portion 116 of
the actuator functions as a cam surface during this
rotation and causes plston assembly 26 to move
downward from its inactive/ready position to puncture
seal 22. Lanyard 98 ancl ball 100 pull free of the
valve through opening 110 once actuation has been
completed.
Valve 13 operates in response to the actuation
of actuator assembly 86 as follows. The initial
rotation of actuator 88 causes piston assembly 26 to
move downward thus breaking the connection between
crossed-ports 52 and vents 54 and forming a
connection between those ports and portion 36 of
chamber 24. This downward movement also causes exit
conduit 56 to become connected to portion 36, rather
than portion 34, of chamber 24. As this downward
movement takes place, the air in portion 34 of
chamber ~4 leaves valve 13 by means of channels 72 in
seal plate 38 and vent passages 74.
Once ports 52 and exit conduit 56 are both
connected to portion 36 o~ chamber 24, puncturing o~
seal 22 begins. Leading edge 29 of cutter 28 causes
the initial puncture. The gas escaping from the
initial puncture passes into the cutter's opening 25,
~hrough conduit 48, and out of ports 52, where it
fills portion 36 of chamber 24 and causes piStOTl 30
to move downward thus forcing the cutter's leading
edge completely through the cylinder's seal to
complete the puncturing process (see Figures 6 ancl
8).
Thereafter, gas flows from the cylinder through
conduit 48, portion 36 of chamber 24, and out of the
valve through exit conduit 56 (see Figure 8). This
continual flow keeps piston assembly 26 in its full
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downward position. ~ccordingly, exit conduit 56 and
crossed-ports 52 remaln in portion 36 of chamber 24
thus assuring that gas does not escape through vent
passages 54 or 7~. It should be noted that once
inflation has been completed, the final pressure in
the inflated device/cylinder/valve combination will
also act to keep piston assembly 26 in its fully
operated position.
In practice, the valve of the present invention
has been found to reliably puncture cylinders
containing nitrogen gas at pressures on the order of
6,000 psi. The nitrogen gas has, in turn, been used
to successfully inflate life rafts.
The valve can be constructed from conventional
materials normally used in the construction of valve
mechanisms. For example, valve body 14, seal plate
38, outlet assembly 58, piston 30 and its extension 32
can be made out of aluminum, cutter 28 and pins 96 and
104 can be made out of stainless steel, bushing 92 can
be made of brass, O-rings 40, 42, 44, 46, 68, and 70
can be made of silicone, Buna N, or other elastomers
depending on the particular temperature at which the
valve is to be used, and actuator 88, actuator housiny
90 and cover 102 can be made of plastic materials,
such as, Delrin (Trademark), ABS, or polycarbonate
based plastics. Other materials, or course, can be
used if desired.
Although specific embodiments of the invention
have been described and illustrated, it is to be
understood that modifications can be made without
departing from the invention's spirit and scope. For
example, although the valve is of particular value
when used with high pressure cylinders, it can also be
used with low pressure cylinders, such as, carbon
dioxide cylinders. Also, although illustrated herein
.,.
1 3 1 1 1 74
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with reference to a cylinder which has been sealed
with a puncturable disc, the invention can also be
used with poppet type seals in which case the leading
edge of the conduit would open the seal by contacting
and moving the stem of the poppet seal. Similarly,
although of particular benefit where manual actuation
is to be employed, other Eorms of actuation,
including, elèctrical, spring, and detonation
actuation, can be used if clesired.
