Inflation system and valve for use therein

A valve for use in an inflation system wherein the valve has a spring regulated piston which regulates the flow rate through the valve into the inflatable member, such that if the flow rate gets too high, the regulating piston will divert some or all of the flow out a neutral thrust over pressure relief vent, which vents outside the inflatable member. The valve also has a secondary form of overpressure relief in the form of a neutral thrust diffuser which also dumps outside of the inflatable member. Fluid is prevented from flowing out of the neutral thrust diffuser by a burst disk, but if the fluid pressure is high enough, the burst disk will burst, and the fluid will flow out of the neutral thrust diffuser.

BACKGROUND
 The present invention is directed towards an inflation system and a valve
 for use in an inflation system. The present invention is particularly
 suited for inflating inflatable members, such as the emergency exit
 slides, life rafts, etc. carried on commercial aircraft.
 The present invention inflation system utilizes the apparatus for rapid
 inflation of inflatable objects and related method described in U.S. Pat.
 No. 5,988,438 by Lewis et. al, and hereby incorporated herein by
 reference.
 The present state of the art in inflation systems for emergency exit slides
 and rafts in commercial aircraft includes a source of gas which flows into
 an aspirator, which then flows into the inflatable member. Regardless of
 which type of gas source is used (stored compressed gas, pyrotechnic gas
 generator etc.) there is a problem due to the wide ambient temperature
 range within which the inflation systems are required to operate. The
 temperature range over which these systems are required to function is
 from -40.degree. F. to 140.degree. F. The amount of gas available must be
 enough to pressurize the inflatable element at the coldest temperature.
 Because of the relationship between pressure and temperature with a fixed
 volume, as the ambient temperature rises above the minimum, the gas source
 provides too much pressure. To keep the inflatable member from failing due
 to stress from this high pressure, relief valves are incorporated into the
 inflatable member to maintain the desired pressure. Multiple relief valves
 are usually necessary. These relief valves add a significant amount of
 weight to the inflation system, take up a significant amount of space, and
 add cost. An inflation system is desired which can reduce the number and
 size of relief valves necessary, thereby significantly reducing the
 weight, cost, and required space of the inflation system.
 SUMMARY OF THE INVENTION
 A valve comprising a valve body with an inlet port, a charging port, a
 first chamber, a neutral thrust diffuser, a second chamber, a neutral
 thrust over pressure relief vent, and an outlet port.
 The inlet port, and the charging port are in fluid communication with the
 first chamber, and the first chamber has a first outlet and a second
 outlet. The first outlet is blocked by a blocking means, and the second
 outlet is blocked by a secondary burst disk. The blocking means prevents
 fluid communication between the first chamber and the second chamber. An
 actuating means will rupture the blocking means at a predetermined
 actuation point. The second chamber is in fluid communication with the
 outlet port, and/or the neutral thrust over pressure relief vent.
 A regulating piston comprises a piston and a regulating spring wherein the
 piston slidably moves within the second chamber such that the regulating
 piston allows fluid communication between the second chamber and the
 neutral thrust over pressure relief vent, or between the second chamber
 and the outlet port, or both.
 The secondary burst disk prevents fluid communication between the first
 chamber and the neutral thrust diffuser.
 Cross-sectional flow area one is the cross-sectional area of the outlet
 port which is in fluid communication with the second chamber, two examples
 of this are shown in Detail A and Detail B. Cross-sectional flow area two
 is the cross sectional area of the neutral thrust over pressure relief
 vent which is in fluid communication with the second chamber.
 When the actuating means ruptures the blocking means, the fluid flows from
 the first chamber through the first outlet and into the second chamber.
 The fluid exerts pressure on the piston, and slidably moves the piston
 within the second chamber, such that increased fluid pressure causes the
 regulating piston to move in a manner which decreases the cross-sectional
 flow area one. As the fluid pressure continues to increase, the
 cross-sectional flow area one continues to decrease, and the piston
 slidably moves to a position which allows fluid communication between the
 second chamber and the neutral thrust over pressure relief vent. With
 increasing fluid pressure the cross-sectional flow area one continues to
 decrease, and the cross-sectional flow area two continues to increase,
 until the piston can no longer move due to the constraints of the second
 chamber in combination with the regulating spring.
 As the fluid pressure decreases, the piston slidably moves such as to
 decrease the cross-sectional flow area two, and increase the
 cross-sectional flow area one.
 If the fluid in the first chamber reaches a pressure equal to the burst
 pressure of the secondary burst disk, the secondary burst disk will burst,
 allowing the fluid to exit the first chamber through the neutral thrust
 diffuser.

DETAILED DESCRIPTION
 Various aspects of the invention are presented in FIGS. 1-6 which are not
 drawn to scale, and wherein like components are numbered alike. Referring
 now to FIG. 1, according to an aspect of the invention, a valve 1 for use
 in an inflation system is shown. The valve 1 comprises a valve body 3 with
 an inlet port 5, a charging port 6, a first chamber 7, a neutral thrust
 diffuser 9, a second chamber 11, a neutral thrust over pressure relief
 vent 13, and an outlet port 15.
 Still referring to FIG. 1, the inlet port 5, and the charging port 6 are in
 fluid communication with the first chamber 7, and the first chamber 7 has
 a first outlet 17 and a second outlet 19. The first outlet 17 is blocked
 by a blocking means 21, and the second outlet 19 is blocked by a secondary
 burst disk 23. The blocking means 21 prevents fluid communication between
 the first chamber 7 and the second chamber 11. An actuating means will
 rupture the blocking means 21 at a predetermined actuation point. The
 second chamber 11 is in fluid communication with the outlet port 15,
 and/or the neutral thrust over pressure relief vent 13.
 A regulating piston 25 comprises a piston 24 and a regulating spring 26
 wherein the piston 24 slidably moves within the second chamber 11 such
 that the regulating piston 25 allows fluid communication between the
 second chamber 11 and the neutral thrust over pressure relief vent 13, or
 between the second chamber 11 and the outlet port 15, or both.
 The secondary burst disk 23 prevents fluid communication between the first
 chamber 7 and the neutral thrust diffuser 9.
 Referring now to FIGS. 3-5, these figures show various ways in which fluid
 can flow through the valve. Cross-sectional flow area one 48 is the
 cross-sectional area of the outlet port 15 which is in fluid communication
 with the second chamber 11, two examples of this are shown in FIG. 3A and
 FIG. 4A. Cross-sectional flow area two 50 is the cross sectional area of
 the neutral thrust over pressure relief vent 13 which is in fluid
 communication with the second chamber 11. The directional arrows in FIG.
 3A and FIG. 4A show the direction in which the cross-sectional flow area
 is measured, which is perpendicular to the direction of the flow.
 When the actuating means ruptures the blocking means 21, the fluid flows
 through to the second chamber 11 this is illustrated in FIG. 3. The fluid
 exerts pressure on the regulating piston 25, and slidably moves the piston
 24 within the second chamber 11, such that increased fluid pressure causes
 the regulating piston 25 to move in a manner which decreases the
 cross-sectional flow area one 48. As the fluid pressure continues to
 increase, the cross-sectional flow area one 48 continues to decrease, and
 the piston 24 slidably moves to a position which allows fluid
 communication between the second chamber 11 and the neutral thrust over
 pressure relief vent 13 this is illustrated in FIG. 4. With increasing
 fluid pressure the cross-sectional flow area one 48 continues to decrease,
 and the cross-sectional flow area two 50 continues to increase, until the
 piston 24 can no longer move due to the constraints of the second chamber
 11 in combination with the regulating spring 26.
 As the fluid pressure decreases, the piston 24 slidably moves such as to
 decrease the cross-sectional flow area two 50, and increase the
 cross-sectional flow area one 48.
 If the fluid in the first chamber 7 reaches a pressure equal to the burst
 pressure of the secondary burst disk 23, the secondary burst disk 23 will
 burst, allowing the fluid to exit the first chamber 7 through the neutral
 thrust diffuser 9 this is illustrated in FIG. 5.
 According to a further aspect of the invention, when the piston 24 can no
 longer move due to the constraints of the second chamber 11 in combination
 with the regulating spring 26, the piston 24 blocks all fluid
 communication between the second chamber 11 and the outlet port 15, such
 that all fluid is flowing out of the neutral thrust over pressure relief
 vent 13.
 In a preferred embodiment of the invention, the piston 24 will slidably
 move to change the cross-sectional flow area one 48 and the
 cross-sectional flow area two 50 in a manner which will control the flow
 rate to meet particular mass flow output rates.
 According to an aspect of the invention, a fill valve 33 and a fusible plug
 35 are installed in the charging port 6. In a further aspect of the
 invention, the valve body 3 has a second port 37, and a pressure
 indication device 39 is installed in the second port 37.
 In a preferred embodiment of the invention, the valve body 3 has both a
 charging port 5 and a second port 37. A fill valve 33 and a fusible plug
 35 are installed in the charging port 5; and a pressure indication device
 39 is installed in the second port 37. For convenience, both ports may be
 standard MS33649 ports.
 In a further preferred embodiment of the invention, the regulating piston
 25 further comprises a regulating spring adjuster 28. Use of a regulating
 spring adjuster 28 can compensate for tolerances in the spring rate of the
 regulating spring 26. This is done by moving the regulating spring
 adjuster 28 either closer to the piston 24 to further compress the
 regulating spring 26, or further from the piston 24 to allow the
 regulating spring 26 to further expand. This enables a designer to more
 accurately meet specified mass flow output criteria.
 In a preferred embodiment of the invention, the blocking means 21 is a
 primary burst disk, and the actuating means is the fluid pressure, such
 that when the fluid pressure in the first chamber 7 is above the burst
 pressure of the primary burst disk, the burst disk will burst, allowing
 the fluid to flow into the second chamber 11. When a primary burst disk is
 used, the burst pressure for the primary burst disk will be less than the
 burst pressure for the secondary burst disk 23. There are other blocking
 means and actuating means which are well known in the art, and which would
 also be suitable. For example, a burst disk whose burst pressure is above
 expected fluid pressure could be used for the blocking means. A spring
 operated knife blade could be used for the actuation means; either with
 manual actuation, or with a pyrotechnic gas source such as a squib to
 provide the force necessary to thrust the knife blade through the burst
 disk. As another example, the blocking means may be a burst disk with a
 burst pressure which is less than the lowest expected fluid pressure, but
 which is supported by a removable support means. The actuation means in
 this case would be removing the burst disk support, so that the fluid
 pressure is able to burst the disk, and flow through to the second
 chamber.
 FIG. 6 depicts the invention inflation system 40 for inflation of an
 inflatable member, comprising a gas source 42, and any aspect of the valve
 1 as described above.
 In a further aspect of the invention, the gas source 42 is a stored
 pressurized gas source. Alternatively, the gas source 42 is a pyrotechnic
 gas generator source.
 In a preferred embodiment of the invention, the gas source 42 is an
 inflator device adapted for producing a sufficient quantity of a gaseous
 product to substantially inflate an inflatable member operatively
 associated therewith, comprising: a first stage gas source 60; a second
 stage gas source product to substantially inflate an inflatable member
 operatively associated therewith, comprising: a first stage gas source 60;
 a second stage gas source 62 of liquefied gas in fluid communication at a
 first location 64 with the first stage gas source 60 and at a second
 location 66, with the valve 1. Wherein the first stage gas source 60 is
 capable of providing a sufficient quantity of gas at a sufficiently high
 temperature to vaporize substantially all of the liquefied gas in the
 second stage gas source 62.
 In a further preferred embodiment, the inflation system 40 further
 comprises an aspirator which receives the fluid from the valve outlet port
 15, and also pulls in ambient air, and allows the combination to flow
 through to the inflatable member. Suitable aspirators are well known to
 those in the art of inflation systems for inflating inflatable members,
 such as the emergency exit slides, life rafts, etc. carried on commercial
 aircraft. One example of suitable aspirators are those described in U.S.
 Pat. No. 4,368,009 by Heimovics and Seabase, which is hereby incorporated
 by reference.
 In a particular preferred embodiment of the present invention, the first
 stage gas source 60 and the second stage gas source 62 are in fluid
 communication, such that, gas produced or stored in the first stage is
 introduced into the liquefied gas in the second stage gas source 62,
 thereby vaporizing the liquefied gas and increasing the pressure within
 the second stage gas source 62. The second stage gas source 62 is in
 constant fluid communication with the first chamber 7 of the valve 1. The
 increased pressure within the second stage gas source 62 thus translates
 into increased pressure within the first chamber 7 of the valve 1. The
 valve 1 is preferably a high strength aluminum forged body, anodized and
 sealed following machining. When this increased pressure is high enough,
 it causes the primary burst disk to burst, allowing the gas to continue on
 to the second chamber 11 of the valve 1. The burst disks are preferably
 stainless steel.
 Once in the second chamber 11 of the valve 1, the gas pressure will act on
 the regulating piston 25. The piston 24 is preferably 6061-T6 aluminum
 alloy, with a hard coat anodized coating after machining, and a minimum 16
 RMS surface finish in the contact areas. The inside wall 27 of the second
 chamber 11 that the piston 24 rides in is preferably the same material,
 treatment, and finish as the piston 24. The clearance between the in. The
 regulating spring 26 is preferably stainless steel. All stainless steel
 hardware that contacts aluminum hardware is preferably passivated, and
 then cadmium plated to minimize the potential for electro-galvanic
 corrosion.