Note: Descriptions are shown in the official language in which they were submitted.
90~7
,
R~E'T INF~I'ION VAI.V~
~ACKG~OU~D OF TIIE INVENTION
l. Field of the Invention.
The present invention relates to life raft
05 inflation equipment. In particular, the presellt
invclltion relates to an improved raft inflation valve
~:hich controls the flow of pressurized gas from a
~ressure vessel to an inflatable life raft.
2. Description of the Prior ~rt.
]0 Inflatable life rafts have found wide use on
ocean-going ships and aircraft. ~n inflatable life
raft offers the advantage of light weight and small
size. It is stored in its deflated condition for
10ll(3 periods of time when it is not needed, and yet
can be inflated rapidly when it is needed to form a
large raft capable of holding relati~ely large
nurnbers of people.
Inflatable life rafts are inflated usin~ a
pressurized inflation gas (such as carbon dioxide,
clry air, or nitrogen) which is contained in a
pressure tank. When the raft is to be inflated, a
valve is actuated by pulling a pull cable which is
connected at one end to the valve actuating mecllallism
in such a manner so as to allow the cable to pull
free after the actuating mechanism has been
actuated. The pull cable is typically connected at
its other end to the ship. The pull cable is
automatically pulled, therefore, when the raft is
throwrl overboard or when the ship sinks. The valve
opens when actuated to permit the pressurized fluid
to expand and fill the life raft.
Originally, and prior to the advent of higl
pressure technology, all inflation systems used
carbon dioxide stored in liquid form in the pressure
tallk. Carbon dioxide undergoes a phase change from
3~
-- 2 --
liquid to gas when the valve is actuated and the raft
is inflated. Becase of severe thermodynamic effects
on temperature caused by the phase change and rapid
pressure drop, carbon dioxide has a tendency to
freeze (form dry ice) or slush-up in cold weather.
This fre~uently causes a "plugged" valve which
results in a slow or partial inflation that can
render the raft of little or no emergency use value.
To overcome the shortcomings of the carbon
dioxide raft inflation systems, systems using
pressurized dry air as the inflation gas were
developed and perfected by the U.S. ~avy during the
middle 1970's. The dry air systems do not suffer
from the freeze-up problems associated with carbon
dioxide systems. They do require, however, that the
dry air be stored at a much higher pressure (normally
in the range of about 5,000 psi) because dry air does
not undergo a phase change expansion liXe carbon
dioxide. The advent of the high pressure dry air
systems for life raft inflation required the
development of raft inflation valves which were
capable of operating reliably at these high
pressures, while at the same time offering low
activating force. One highly advantageous raft
inflation valve has been the Marada Mark VI valve
manufactured and sold by Marada Research and
-Manufacturing of Chaska, Minnesota. This valve, two
of which are used on the U.S. ~avy's 25-man Mark VI
raft, is a stainless steel valve with a movable
spool. The spooi is biased by a spring to maintain
the valve in a normally closed position. When the
pull cable is pulled, it causes a cam to be rotated,
which moves the spool against the spring force to
open the valve.
21 B 84
L2~29~)7
-- 3
The r~arada Mark VI valve has provided very
reliable operation at the high pressures, and is
capable of being actuated with a relatively low pull
force on the pull cable (typically less than 20
05 pounds). The Marada Mark VI valve, however, because
of the intricate design and the relatively large
number of high precision parts required, has been
expensive to manufacture. In addition, like other
raft inflation valves, it has been susceptible to
contamination if the source of the inflation gas (in
this case dry air) contains dust, dirt particles, or
other contaminants.
Thus there has been a continuing need for an
improved raft inflation valve which provides
ultra-high reliability, is capable of handling high
pressures ~up to for example, 6,000 psi), has a low
actuating force, is not affected by contamination or
environmental changes, and is easy and relatively
inexpensive to manufacture. Furthermore, because of
a large number of existing problems associated with
either marginal valve performance or corrosion
related to the improper use of dissimilar metal
components (e.g. brass valves and aluminum cylinders)
there is a significant need for an improved valve
which is capable of retrofitting to existing life
raft inflation systems.
SUMMARY OF THE INVENTION
The present invention is a valve which is
normally closed, and which is actuated to permit the
flow of pressurized gas from a pressure vessel to an
outlet connected, for example, to an inflatable life
raft. The valve of the present invention includes a
valve body, a double-ended piston, and valve
actuating or actuating means for causing the valve to
open in order to inflate the raft.
~,. . .
,~ -
12~ 7
-- 4 --
The valve body of the valve of the present
invention includes an inlet, an outlet, an internal
cylinder, and an inlet passage. The internal
cylinder is open at a first end to the outlet. The
05 inlet passage extends from the inlet and intersects
the internal cylinder.
The double-ended piston, which is movable in
the internal cylinder, has first and second heads
with ends of equal diameter, and first and second
spaced-apart O-ring seals. In the normally closed
condition of the valve, the piston is positioned so
that the O-ring seals are positioned on opposite
sides of the inlet passage when the valve is in its
normally closed condition. The O-ring seals,
therefore, block gas flow between the inlet and the
outlet.
This results in a balancing of the gas
pressure forces acting on the piston, while allowing
the piston to be moved (for actuation of the valve)
simply by overcoming the O-ring drag on the internal
cylinder wall.
The valve actuating means is pulled to cause
the piston to move away from the first end and toward
the second end of the cylinder. Once the
intersection of the internal cylinder and the inlet
passage is partially uncovered, the gas pressure
forces become unbalanced. The pressure of the gas
accelerates the piston in its movement away from the
outlet once the intersection of the internal cylinder
and the inlet passage is partially uncovered.
In preferred embodiments of the present
invention, the valve body includes an auxiliary
passage which intersects the inlet passage at a
position between the inlet and the internal
cylinder. A fill fitting is attached to the valve
., ,. ` :
. -- ,
~ 5 - i2~ 907
body and connects with the auxiliary passage to
permit pressurized gas to be supplied to the pressure
vessel or removed from the pressure vessel through a
flow path which includes the inlet, the inlet
05 passage, the auxiliary passage and the fill fitting.
Because all filling or removing of gas from the
pressure vessel is provided without having to move
the piston and does not use the outlet, the danger of
contamination of the piston, the internal cylinder or
the outlet during the filling process is avoided.
In one embodiment of the present invention,
the piston also includes a piston rod which is
connected to the second piston head and which extends
out of the second end of the internal cylinder. In
this embodiment, the actuating means, when pulled,
pulls the piston rod to cause the piston to move in
an axial direction toward the second end of the
cylinder.
In another embodiment of the present
invention, the valve includes spring bias means for
applying a spring bias to the piston in an axial
direction toward the second end of the internal
cylinder. The actuating means in this embodiment
normal1y engages the piston to prevent axial movement
of the piston from the normally closed position.
I~hen pulled, the actuating means moves out of
engagement with the piston to permit the spring bias
to move the piston toward the second end of the
internal cylinder.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l is a perspective view of an
inflatable life raft.
Figure 2 is an end view, with portions shown
in ~section, of a first embodiment of the raft
inflation valve of the present invention together
with a pressure tank.
o~
-- 6 --
Figure 3 is a sectional view along section
3-3 of Figure 2.
Figure 4 is a sectional view along section
4-4 of Figure 2.
Figure 5 is a partial end view, partially in
section, of the first embodiment of the raft
inflation valve of the present invention as actuation
of the valve is beginning.
Figure 6 is a sectional view along section
6-6 of Figure 5.
Figure 7 is a perspective view of another
inflatable life raft.
Figure 8 is an end view, with portions shown
in section, of a second embodiment of the raft
inflation valve of the present invention together
with a pressure tank.
Figure 9 is a sectional view along section
9-9 of Figure 8.
Figure 10 is a sectional view along section
10-10 of Figure 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The First Embodiment (Fiqures 1-6)
_
Figure 1 shows inflatable life raft 10 in
its fully inflated condition. The pressurized gas
used to inflate life raft 10 has been supplied from
one or more pressure vessels 12 which are attached to
and carried by raft 10. Pressure vessel or tank 12
is typically a metal or metal-lined fiberglass tank
which contains an inflation gas such as carbon
- 30 dioxide, dry air, or nitrogen, stored under
pressure. Each pressure tank 12 has a raft inflation
valve 14 attached at one end. Under normal storage
conditions, life raft 10 is deflated and stored in a
compact package. A releasable pull cable (not shown
in Figure 1) is connected to valve 14 so that when
21 B 84
--
9o~
-- 7 --
the cable is pulled, valve 14 is actuated. This
causes valve 14 to open, thus allowing the inflation
gas from pressure tank 12 to pass through valve 14
and outlet hose 16 and into the interior of life raft
10.
Figures 2-6 show raft inflation valve 14 of
the present invention in further detail. Figure 2 is
an end view of tank 12 and valve 14 with portions
shown in section. In Figure 2, and in the sectional
views shown in Figures 3 and 4, valve 14 is in its
normal closed state prior to actuation. This is the
state in which valve 14 is found when life raft 10 is
deflated for storage.
Inflation valve 14 includes a stainless
steel valve body 18 which has a threaded neck portion
20, inlet port 22, internal cylinder 24, outlet port
26, inlet passage 28, auxiliary passage 30, fill port
32, safety relief port 34, and retaining bore 36.
Threaded neck portion 20 of valve body 18
connects valve 14 to the end of tank 12. In the
embodiment shown in Figure 3 and 4, threaded neck
portion 20 has a external (male) threads 38 which
mate with internal (female) threads of the port (not
shown) in the end of tank 12. o-ring tank seal 40 is
positioned against shoulder 42 of valve body 18, and
provides a seal between shoulder 42 and tank 12.
Inlet port 22 communicates with the interior
of tank 12. Inlet passage 28 is connected at one end
to inlet port 22, and at its other end it intersects
internal cylinder 24. In the preferred embodiments
of the present invention, the axis of inlet passage
28 intersects and is perpendicular to the axis of
internal cylinder 24.
Outlet fitting 44 is threaded into outlet
port 26, so that outlet passage 46 of outlet fitting
-' 21 B 84
~2~2~907
-- 8 --
44 communicates with one end o~ internal cylinder
24. 0-ring seal 48 provides a seal between outlet
fitting 44 and valve body 18. In the embodiment
shown in Figures 2 and 3, outlet fitting 44 has male
threads S0 at its outer end which allow hose coupling
52 (which has cooperating female threads) to be
connected to outlet fitting 44. Control of gas flow
from inlet 22 through inlet passage 28 and internal
cylinder 24 to outlet passage 46 and hose 16 is
controlled by double-ended piston 54. As shown in
Figure 3, piston 54 includes piston body 56 and
piston rod 58. Piston body 56 is a double-headed
piston body having an 0-ring seal 60 and backup ring
62 near its first end 56A, and O-ring seal 64 and
backup ring 66 near its second end 56B. As shown in
Figure 3, valve 14 is closed, because piston 54 is
positioned so that O-rings 60 and 64 are positioned
on opposite sides of inlet passage 28 to prevent any
leakage in either direction around piston body 56.
Since there is no pressure difference between the
opposite ends 56A and 56B of piston body 56 and no
axial force is being applied to piston rod 58, piston
54 is in a stable, force balanced position within
cylinder 24. Because of the balancing of gas
pressure forces, piston 54 can be moved (for
actuation) simply by overcoming the drag of O-rings
60 and 64 on the wall of internal cylinder 24. This
results in a low actuation force that is only
remotely related to the operating pressure of the
inflation system.
Valve 14 is actuated to an open condition by
` pulling piston rod 58 in the axial direction so that
piston body 56 moves away from outlet port 26 and
toward retaining nut 68, which is threaded into
passage 36. As soon as the end of piston body 56
21 B 84
~''` ' ~
~: .
:' .
- ~ - .- .
- , .
- -
.
. : ' " ' -
~X907
g
clears a portion of the intersection of inlet passage
28 and internal cylinder 24, the pressurized gas
~egins to flow from tank 12 through inlet 22 and
inlet passage 28 into internal cylinder 24. As
O-ring 60 reaches inlet passage 28, the gas pressure
force on piston 54 acting in the direction toward
outlet port 26 drops, while the gas pressure force on
piston 54 acting in the direction of retaining bore
36 is maintained, and thus the gas pressure forces on
piston 54 become unbalanced. This gas pressure force
differentual causes rapid acceleration of the
movement of piston body 56 the remaining distance out
of the way of inlet passage 28, which then allows the
inflation gas to flow freely from inlet port 22 to
outlPt port 26. Retaining nut 68 limits the movement
of piston body 56, so that the force of the
pressurized gas does not blow piston 54 entirely out
of internal cylinder 24.
Since the gas pressure forces acting on
piston 54 are balanced by the double-ended
configuration of piston 54 when the O-rings 60 and 64
are positioned on opposite sides of inlet passage 28
; ~ (valve closed), the pressure of the gas only affects
actuation (pull) force by its effect on O-ring drag.
Thus it can be seen that the actuating force required
to move piston 54 is relatively low, and is in fact
only the force required to overcome the drag at
o-rings 60 and 64.
I The actuating mechanism for valve 14
includes retaining nut 68, retaining guide 70, pull
cable 72, ball 74, flexible conduit 76, conduit
connector 78, safety pin 80 and safety wire 82.
Piston rod 58 extends out of the end of
cylinder 24 through retaining nut 68 and into chamber
84 which is defined by retaining nut 68, retaining
- 21 B 84
-. '
~ r~ 07
-- 10 --
guide 70, and conduit connector 78. The outer end of
piston rod 58 has a detent 86 which receives ball
74. Cable 72 is connected at one end to ball 74 and
extends out of chamber 84 through flexible conduit
76. The outer end of pull cable 72 typically has a
connecting device (not shown) which is attached to
the ship.
Safety pin 80 shown in Figures 2 and 3
prevents accidental or unintended actuation of valve
14 by preventing axial movement of piston 54. Pin 80
is inserted through openings 90 in retaining guide
72, so that the shank of pin 80 butts the outer end
of piston rod 58. As long as safety pin 80 is in
place, piston 54 cannot be moved in the axial
direction by pull cable 72.
When safety pin 80 is removed (as shown in
Figure 5), a pulling force on cable 72 causes ball 74
to move in the axial direction, thus pulling piston
rod 58 outward in the axial direction. Chamber 84
has a portion 84A of smaller diameter which maintains
ball 74 and detent 88 in a force transmitting
relationship until piston rod 58 has been pulled far
enough out that inlet passage 28 is partially
uncovered by piston body 56. At that point, which is
illustrated in Figures 5 and 6, ball 74 has reached
second chamber portion 84B of a larger diameter.
Ball 74 is then allowed to escape from detent 86, so
that pull cable 72 can be pulled entirely out of
chamber 84 and flexible conduit 76. Pull cable 72
must release valve 14 at the end of its stroke,
because pull cable 72 is normally attached at its
outer end to the ship, and valve 14 is actuated when
life raft 10 is thrown overboard or when the ship
sinXs. In that type of application, cable 72 must
;35 disconnect entirely from valve 14 at the end of its
21 B 84
~2~2~)7
-- 11
stroke, so that life raft 10 is totally disconnected
~rom the ship.
Portion 84A of chamber 84 has a diameter
which is sufficiently small so that there is only one
S possible orientation of ball 74 and detent 86. sall
74 cannot hang up or become lodged anywhere else in
chamber 84 or in conduit 76.
Flexible conduit 76 provides a flexible
guide for pull cable 72. The use of flexible conduit
76 allows cable 72 to apply an axial pulling force on
piston rod 58 regardless of the direction of the
pulling force on cable 72. In other embodiments,
flexible conduit 76 and conduit connector 78 are
replaced by a round nose ferrule.
Safety wire 82 is threaded through safety
wire passage 91, which extends through retaining nut
68 and piston rod 58. The outer ends of safety wire
82 are preferably twisted together, as shown in
Figure 2. Safety wire 82 provides a visual
indication as to wheth~r valve 14 has already been
actuated. Safety wire 82 is broken when a pulling
force is applied to piston rod S8 which results in
actuation of valve 14.
An important advantage of valve 14 of the
2S present invention is that it permits tank filling,
tank bleed down, pressure measurement, and system
(i.e. tank and valve) pressure proof testing without
disturbance of piston S4 and without exposing
internal cylinder 24, piston S4, and outlet fitting
44 to possible contamination that could subsequently
result in inflation system failure. As best shown in
Figure 4, auxiliary passage 30 intersects inlet
passage 28 between inlet port 22 and internal
cylinder 24. Fill fitting assembly 92, which
includes housing 94 and fill valve 96, is attached
21 B 84
: - .
. .
' :' . ' ~
.
~.~229~7
to valve body 18 at fill port 32. Housing 94 has
threads 98 which are threaded into fill port 32.
o-ring 100 provides a seal between valve body 18 and
housing 94.
Fill valve 96 is threaded into housing 94,
and has an inner end 102 which engages valve seat 104
of fill port 32. 0-ring 110 and backup sing 112
provide a seal between fill valve 96 and housing 94.
An internal passage 114 extends substantially the
entire length of fill valve 96. Passage 114 ends at
inner end 102 of fill valve 96, where it is
intersected by passage 116.
At the outer end of fill valve 96 are male
threads 118, which permit connection of other
apparatus to fill fitting assembly 92 such as a
source of gas (when tank 12 is to be filled), a
pressure gauge (when the pressure in tank 12 is to be
measured), or backup seal/threaded protector cap 120
as shown in Figure 2 (under normal storage and use
conditions).
When tanX 12 is being filled or bled down or
when pressure measurement or proof testing i8 being
performed through fill fitting 92, fill valve 96 is
backed out of housing 94 partially so that valve end
102 i8 no longer in engagement with valve seat 104.
This permits gas flow between passage 114 of fill
valve 96 and auxiliary passage 30 in valve body 18.
Even when fill valve 96 is partially backed out,
O-ring 110 maintains a seal between fill valve 96 and
housing 94, so that the gas flow through fill fitting
assembly 92 is controlled. To again bring valve end
102 into engagement with valve seat 104, fill valve
96 is rotated in an opposite direction. In any
filling operation, the possibility of contamination
being introduced exists. Fill assembly 92 minimizes
. ,.
21 B 84
. . .
" . ' . ' ~ ' " ' ' ' ', ' : '
. - -
.
.. ~ . . . . : -
, :
- ~ ~
~222~07
- 13 -
the effects of contamination. First, if a soft
contaminant is present at valve seat 104, the force
applied as fill valve 96 is threaded inwardly into
housing 94 tends to crush and displace the
contamination. If a hard contaminant is present at
valve seat 104, any leak at valve seat 104 is still
minimized. In addition, by placing cap 120 on the
outer end of valve 96, passage 114 is still sealed,
because flare 122 at the outer end of valve 96
engages seat 124 of cap 120.
Valve 14 also includes a safety relief which
prevents an explosion in the event that gas pressure
within tank 12 reaches an unsafe level. The safety
relief includes frangible disc 126 and disc retaining
nut 128. Frangible disc 126 is located in safety
port 34 at an opposite end of auxiliary passage 30
from fill fitting assembly 92. Retaining nut 128 is
threaded into safety relief port 34, and holds
frangible disc 126 in a position where it seals
safety relief port 34. If the pressure within tank
12, and therefore within auxiliary passage 30,
exceeds a predetermined level, frangible disc 126
ruptures. This permits inflation gas to flow out of
tank 12, through inlet port 22, inlet passage 28 and
auxiliary passage 30, through disc 126 into passage
130 of retaining nut 128, and out discharge vents 132.
As discussed previously, the valve 14 of the
present inventon permits proof testing of the
inflation system (i.e. tank and valve together)
through fill fitting assembly 92, without damage to
valve 14. Because the proof testing involves
pressures which are higher than the safety pressure,
safety relief port 34 must be blocked so that
frangible disc 126 is not ruptured during system
proof testing.
21 B 84
:;'
j~, !~~, . . "
~' .
'''~ '
.~ . .
~ ', ,
': `' ` ~
12~2907
- 14 -
The raft inflation valve 14 of the present
invention provides a number of significant
advantages. First, it provides ultra-high
reliability because the portion of valve 14 which
05 contro]s flow between inlet port 22 and outlet port
26 is not affected by contamination or environmental
c~langes. Tank filling, tank bleed down, pressure
measurement, and system proof testing can be
performed independently through fill fitting 92.
Second, valve 14 is capable of operating
over a wide pressure range, preferably up to and
including 6,000 psi. This makes valve 14 usable with
any of the commonly available inflation gases.
Third, the actuating of valve 14 involves
only one moving part. This greatly enhances
reliability and also makes valve 14 much easier to
manufacture.
Fourth, valve 14 requires a very low
actuating force (typically 10 to 20 pounds) even when0 the inflation gas is at a very high pressure.
The Second Embodiment (Figures 7-10)
Figure 7 shows inflatable life raft 10 in
its fully inflated condition. The pressurized gas
used to inflate life raft 210 has been supplied from
one or more pressure vessels 212 which are attached
to and carried by raft 210. Pressure vessel or tank
212 is typically a metal or metal-lined fiberglass
tank which contains an inflation gas stored under
pressure. Each pressure tank 212 has a raft
inflation valve 214 attached at one end. ~nder
normal storage conditions, life raft 210 is deflated
and stored in a compact package. A pull cable 215,
(Figure 9) is connected to a removable actuating pin
216 ~Figures 8 and 9) of valve 214 so that when cable
215 is pulled, actuating pin 216 is pulled out of
1222907
- 15 -
valve 214 and valve 214 is actuated. This causes
valve 214 to open, thus allowing the inflation ~as
from pressure tank 212 to pass through valve 214 and
outlet hosa 217 and into the interior of life raft
05 210.
Figures 8-10 show raft inflation valve 214
of the present invention in further detail. Figure 8
is an end view of tank 212 and valve 214 with
portions shown in section. In Figure 8, and in the
sectional views shown in Figures 9 and 10, valve 214
is in its normal closed state prior to actuation.
This is the state in which valve 214 is found when
life raft 210 is deflated for storage.
Inflation valve 214 includes a hexagonal
stainless steel valve body 218 which has a threaded
neck portion 220, inlet port 222, internal cylinder
224, outlet port 226, inlet passage 228, auxiliary
passage 230A, safety passage 230B, fill port 232,
safety relief port 234, actuating pin passage 235,
threaded pin guide receptacle 236, and vent 237.
Threaded neck portion 220 of valve body 218
connects valve 214 to the end of tank 212. In the
embodiment shown in Figure 9, threaded neck portion
220 has a external tmale) threads 238 which mate with
internal (female) threads of the port (not shown) in
the end of tank 212. 0-ring tank seal 240 is
positioned against shoulder 242 of valve body 218,
and provides a seal between shoulder 242 and tank
212. It should be appreciated that in those
embodiments in which valve 214 is to be used with a
tank 212 having male rather than female threads,
internal (female) threads are provided on the inner
surface of inlet port 222.
Inlet port 222 communicates with the
interior of tank 212. Inlet passage 228 is connected
at one end to inlet port 222, and at its other end
~1222907
- 16 -
it intersects internal cylinder 224. In the
preferred embodiments of the present invention, the
axis of inlet passage 228 intersects and is
perpendicular to the axis of internal cylinder 224.
05 Outlet fitting 244 is threaded into outlet
port 226, so that outlet passage 246 of outlet
fitting 244 communicates with one end of internal
cylinder 224. O-ring seal 248 provides a seal
between outlet fitting 244 and valve body 218. In
the embodiment shown in Figures 8 and 9, outlet
fitting 244 has male threads 250 at its outer end
which allow hose coupling 252 (which has cooperating
female threads) to be connected to outlet fitting 244.
Control of gas flow from inlet 222 through
inlet passage 228 and internal cylinder 224 to outlet
passage 246 and hose 217 is controlled by
double-ended piston 254. As shown in Figure 9,
piston 254 is a double-ended piston having a first
piston head 256A with an O-ring seal 260 and backup
ring 262 and second piston head 25GB with an O-ring
seal 264 and backup ring 266. As shown in Figure 9,
valve 214 is closed, because piston 254 is positioned
so that O-rings 260 and 264 are positioned on
opposite sides of inlet passage 228 to prevent any
leakage in either direction around piston 254. Since
there is no pressure difference between the opposite
ends of piston 254 (because the ends of piston heads
256A and 256B are of equal diameter), piston 254 can
be moved (for actuation) simply by overcoming the
drag of O-rings 260 and 264 on the wall of internal
cylinder 224. This results in a low actuation force
that is only remotely related to the operating
pressure of the inflation system.
Valve 214 is actuated to an open condition
by a actuating mechanism which includes actuating pin
:122Z907
- 17 -
216, actuating pin guide 268, and compression spring
270. Actuating pin guide 268 is threaded into
recepticle 236 and has a guide bore 272 which is
aligned with actuating pin passage 235. As shown in
05 Figure 9, actuating pin 216 is normally inserted
through bore 272 and passage 235, so that the inner
end of actuating pin 216 is positioned in internal
cylinder 224 and engages the end of piston head 256B.
The end of piston head 256B is urged into
engagement with actuating pin 216 by an axial bias
force provided by compression spring 270. As shown
in Figure 9, compression spring 270 is carried within
an enlarged portion of outlet passage 246 near the
outlet end of internal cylinder 224. One end of
compression spring 270 acts against internal shoulder
274 of outlet fitting 244 and the other end of
compression spring 270 acts against the end of piston
head 256A.
Actuating pin 216 has a pull ring 276
attached at its outer end for connection to pull
cable 215. ~hen a pulling force is applied through
cable 215 to pull ring 276, actuating pin 216 is
pulled out of internal cylinder 224, actuating pin
passage 235, and guide passage 272. Once actuating
pin 216 is out of engagement with the end of piston
head 256B, compression spring 270 moves piston 254
away from outlet port 226 and toward vent 237. As
soon as the end of piston head 256A clears a portion
of the intersection of inlet passage 228 and internal
cylinder 224, the pressurized gas begins to flow from
pressure ves~el 212 through inlet 222 and inlet
passage 228 into internal cylinder 224. As O-ring
260 reaches inlet passage 228, the gas pressure force
on piston 254 acting in the direction toward outlet
port 226 drops, while the gas pressure force on
. .
~.
~ '
~. ,,
': :
:, ~ ' -, ~ ........... . ' ,
:
.: .
:1222~307
piston 254 acting in the direction toward vent 237 is
maintained, and thus the gas pressure forces on
piston 254 become unbalanced. This gas pressure
force differential causes rapid acceleration of the
05 movement of piston 254 the remaining distance out of
the way of inlet passage 228, which then allows the
inflation gas to flow freely from inlet port 222 to
outlet port 226. Vent 237 allows air at the opposite
end of cylinder 224 to escape, but is small enough to
limit the movement of piston 254, so that the force
of the pressurized gas does not blow piston 254
entirely out of valve body 218.
Since the gas pressure forces acting on
piston 254 are balanced by the double-ended
configuration of piston 254 when the O-rings 260 and
264 are positioned on opposite sides of inlet passage
228 (valve closed), the pressure of the gas only
affects the bias force required from spring 270 by
its effect on O-ring drag. Thus it can be seen that
the bias force required to move piston 254 is
relatively low, and is in fact only the force
required to overcome the drag at O-rings 260 and
264. Compression spring 270 is preferably a
relatively stiff spring, so as to provide more than
enough bias force to move piston head 256 when
actuating pin 216 is removed.
In order to prevent accidental or unintended
actuation of valve 214 by small forces on cable 215
or pull ring 276, a spring-loaded safety ball catch
278 is carried at the inner end of actuating pin
216. Safety ball catch 278 resists the removal of
actuating pin 216 from internal cylinder 224 unless
there is a sufficient pull force on actuating pin 16
to depress safety ball catch 278 and allow it to pass
into actuating pin passage 235.
'
i~22~g~7
- 19 ~
~ en valve actuation occurs, pull cable 215
and actuating pin 216 must release valve 214, because
pull cab~e 215 is normally attached at its outer end
to the s~ip, and valve 214 is actuated when life raft
05 210 is thrown overboard or when the ship sinks. In
that type of application, cable 215 and actuating pin
216 must disconnect entirely from valve 214, so that
life raft 210 is totally disconnected from the ship.
In the embodiment shown in Figures 8 and 9,
actuating pin 216 is oriented so that the pull force
for actuation is parallel to the longitudinal axis of
pressure vessel 212 and valve 214. Tnis "end pull"
configuration is particularly advantageous for
retrofit applications, because the vast majority of
- 15 current life raft systems use this configuration.
Safety wire 280 (Figure 8) is threaded
through saEety wire passage 282 (Figure 9), which
extends through guide nut 268 and actuating pin 216.
The outer ends of safety wire 280 are preferably
twisted together, as shown in Figure 8. Safety wire
280 provides a visual indication as to whether valve
214 has already been actuated. Safety wire 280 is
broken when a pulling force is applied to actuating
pin 216 which results in actuation of valve 214.
An important advantage of valve 214 of the
present invention is that it permits tank filling,
tank bleed down, pressure measurement, and system
(i.e., tank and valve) pressure proof testing without
disturbance of piston 254 and without exposing
internal cylinder 224, piston 254, and outlet fitting
244 to possible contamination that could subsequently
result in inflation system failure. As best shown in
Figure 10, auxiliary passage 230A intersects inlet
passage 228 between inlet port 222 and internal
cylinder 224. Fill fitting assembly 292, which
~2~ 07
- 20 -
includes housing 294 and fill valve 296, is attached
to valve body 218 at fill port 232. Housing 294 has
threads 298 which are threaded into fill ~ort 232.
0-ring 300 provides a seal between valve body 218 and
housing 294.
Fill valve 296 is threaded into housing 294,
and has an inner end 302 which engages valve seat 304
of fill port 232. 0-ring 310 and backup ring 312
provide a seal between fill valve 296 and housing
294. An internal passage 314 extends substantially
the entire length of fill valve 296. Passage 314
ends at inner end 302 of fill valve 296, where it is
intersected by passage 316.
At the outer end of fill valve 296 are male
threads 318, which permit connection of other
apparatus to fill fitting assembly 292 such as a
source of gas (when tank 212 is to be filled), a
pressure gauge (when the pressure in tank 212 is to
be measured), or backup seal/threaded protector cap
320 as shown in Figure 8 ~under normal storage and
use conditions).
When tank 212 is being filled or bled down
or when pressure measurement or proof testing is being
performed through fill fitting 292, fill valve 296 is
backed out of housing 294 partially so that valve end
302 is no longer in engagement with valve seat 304.
This permits gas flow between passage 314 of fill
valve 296 and auxiliary passage 230 in valve body 218.
Even when fill valve 296 is partially backed out,
o-ring 310 maintains a seal between fill valve 296
and housing 294, so that the gas flow through fill
fitting assembly 292 is controlled. To again bring
valve end 302 into engagement with valve seat 304,
fill valve 296 is rotated in an opposite direction.
In any filling operation, the possibility of
21 B 84
07
- 21 -
contamination being introduced exists. Fill assembly
292 minimizes the effects of contamination. First,
if a soft contaminant is present at valve seat 304,
the force applied as fill valve 296 is threaded
inwardly into housing 294 tends to crush and displace
the contamination. If a hard contaminant is present
at valve seat 304, any leak at valve seat 304 is
still minimized. In addition, by placing cap 320 on
the outer end of valve 296, passage 314 is still
sealed, because flare 322 at the outer end of valve
296 engages seat 324 of cap 320.
Valve 214 also includes a safety relief
which prevents an explosion in the event that gas
pressure within tank 212 reaches an unsafe level.
The safety relief includes frangible disc 326 and
disc retainer nut 328. Frangible disc 326 is located
in safety port 234 at an outer end of safety passage
23OB. At its inner end, safety passage 23OB
intersects inlet passage 228 at a position between
inlet port 222 and internal cylinder 224. Retainer
328 i9 threaded into safety relief port 234, and
hol~s fransible disc 326 in a position where it seals
safety relief port 234. If the pressure within tank
212, and therefore within auxiliary passage 230,
exceeds a predetermined level, frangible disc 326
ruptures. This permits inflation gas to flow out of
tank 212, through inlet port 222, inlet passage 228
and safety passage 230B, through disc 326 into
passage 330 of retainer 328, and out discharge vents
332.
As discussed previously, the valve 214 of
the present inventon permits proof testing of the
inflation system (i.e., tank and valve together)
through fill fitting assembly 292, without damage to
valve 214. Because the proof testing involves
21 B 84
. .
12~907
- 22 -
pressures which are higher than the safety pressure,
safety relief port 234 must be blocked so that
frangible disc 326 is not ruptured during system
~ proof testing.
The raft inflation valve 214 of the present
invention provides a number of significant
advantages. First, it provides ultra-high
reliability because the portion of valve 214 which
controls flow between inlet port 222 and outlet port
226 is not affected by contamination or environmental
changes. Tank filling, tank bleed down, pressure
measurement, and system proof testing can be
performed independently through fill fitting 292.
Second, valve 214 is compact, relatively
light-weight, uses a small number of parts and is
easier to manùfacture than prior art valves.
Third, valve 214 requires a very low
actuating force even when the inflation gas is at a
high preæsure.
Conclusion
Although the present invention has been
described with reference to preferred embodiments,
workers skilled in the art will recognize that
changes may be made in form and detail without
departing from the spirit and scope of the invention.
21 B 8
'
:
