Abstract:
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.

Description:
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° F. to 140° 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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of an aspect of a valve according to the invention. 
     FIG. 2 is a cross-sectional view of an aspect of a valve according to the invention, in use at a first point in time. 
     FIG. 3 is a cross-sectional view of an aspect of a valve according to the invention, in use at a second point in time. 
     FIG. 3A is a detail of cross-sectional flow area one. 
     FIG. 4 is a cross-sectional view of an aspect of a valve according to the invention, in use at a third point in time. 
     FIG. 4A is a detail of cross-sectional flow area two. 
     FIG. 5 is a cross-sectional view of an aspect of a valve according to the invention, in use during an overpressure event. 
     FIG. 6 is a cross-sectional view of an aspect of an inflation system according to the invention. 
    
    
     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.  3 A and FIG.  4 A. 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.  3 A 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.