Abstract:
An aspirator for inflating an aircraft evacuation slide, emergency raft or other inflatable device includes a flexible, collapsible aspirator barrel that is inflated during operation to form a substantially rigid tube. According to one embodiment, the inflatable support member receives a flow of high pressure air directly from the aspirator injector nozzle assembly. According to another embodiment, the collapsible aspirator barrel receives a flow of high pressure gas directly from the high pressure inflation source. Because the aspirator barrel of the present invention is collapsible, the present invention occupies significantly less space when stored than an equivalent aspirator with a rigid aspirator barrel.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to apparatus for inflating devices, in particular to apparatus for inflating aircraft emergency evacuation slides and rafts. 
     Aircraft emergency evacuation slides, emergency life rafts and similar devices are typically stored in a packed configuration occupying as little space as possible for long periods of time. When called upon for use, these inflatable devices are typically inflated to a relatively low pressure, on the order of 2-3 psig for conventional aircraft evacuation slides up to approximately 7-8 psig for advanced high pressure lightweight evacuation slides. The requirement that the inflatable device in its packed condition occupy a minimum volume dictates that the inflation source comprise a volume of gas stored in a high pressure container, a pyrotechnic gas generator, or a hybrid inflator comprising a pyrotechnic gas generator in combination with a quantity of gas stored at high pressure. 
     Because the aforementioned high pressure inflation sources exhaust a volume of gas at a pressure substantially higher than the inflation pressure of the inflatable device, it is common to use an aspirator to draw atmospheric air into the inflatable device during inflation to augment the high pressure gas flowing into the inflatable device. In the operation of an aspirator, one or more nozzles act as gas injectors, injecting a jet stream of gas at high velocity into the inlet end of an aspirator barrel. The flow of air entering the aspirator barrel reduces the pressure at the inlet end to below atmospheric pressure. Atmospheric air, therefore, enters the aspirator body to be entrained with the jet stream entering the aspirator barrel. The outlet of the aspirator barrel communicates with the interior volume of the inflatable device so that jet stream and the entrained air collectively make up the volume of gas filling the inflatable device. 
     Because the aspirator barrel must be capable of operating at sub-atmospheric pressure without collapsing, aspirators are conventionally equipped with rigid aspirator barrels. Although a rigid aspirator barrel adequately performs the function of entraining atmospheric air into the jet stream produced by the injector nozzle(s) a rigid aspirator barrel adds significant weight and storage volume to the inflatable device. U.S. Pat. No. 5,002,465 to Lagen et al. and U.S. Pat. No. 6,071,084 to Wass et al. suggest aspirators having telescoping aspirator barrels. Although a telescoping aspirator barrel reduces the storage volume of the aspirator to some extent, a telescoping aspirator barrel typically collapses by only about 20% or less and, therefore, 80% or more of the length of the rigid aspirator barrel remains to be stored in the limited volume for storage of the inflatable device. 
     SUMMARY OF THE INVENTION 
     The present invention comprises an aspirator having a flexible, collapsible aspirator barrel. According to an embodiment of the invention, the collapsible aspirator barrel comprises an inflatable support member that is inflated to form a substantially rigid tube. According to one illustrative embodiment, the inflatable support member receives a flow of high pressure air directly from the injector nozzle assembly. According to another illustrative embodiment, the collapsible aspirator barrel receives a flow of high pressure gas directly from the high pressure inflation source. Because the aspirator barrel of the present invention is collapsible, the present invention occupies significantly less space when stored than an equivalent aspirator with a rigid or a telescoping aspirator barrel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The present invention will be better understood from a reading of the following detailed description, taken in conjunction with the accompanying drawing figures in which like references designate like elements and, in which: 
         FIG. 1  is cross-sectional view of an inflation system including an aspirator incorporating features of the present invention shown in its stowed condition; 
         FIG. 2  is the aspirator of  FIG. 1  shown in its deployed condition; 
         FIG. 3  is a perspective view of the aspirator of  FIG. 1  in its deployed condition; 
         FIG. 4  is a cross-sectional view of the aspirator of  FIG. 3  taken along line  4 ,  4 ; 
         FIG. 5  is a cross-sectional view of an alternative embodiment of an aspirator incorporating features of the present invention; 
         FIG. 6  is another alternative embodiment of an aspirator incorporating features of the present invention; and 
         FIG. 7  is yet another alternative embodiment of an aspirator incorporating features of the present invention. 
         FIG. 8  is a cross-sectional view of yet another alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The drawing figures are intended to illustrate the general manner of construction and are not necessarily to scale. In the detailed description and in the drawing figures, specific illustrative examples are shown and herein described in detail. It should be understood, however, that the drawing figures and detailed description are not intended to limit the invention to the particular form disclosed, but are merely illustrative and intended to teach one of ordinary skill how to make and/or use the invention claimed herein and for setting forth the best mode for carrying out the invention. 
     With reference to  FIGS. 1-4 , an inflation system  10  for inflating an inflatable device  12  comprises an inflation source  14 , which may be a pressure vessel containing gas under a relatively high pressure, a pyrotechnic gas generator, a hybrid inflator comprising a pyrotechnic gas generator and a stored compressed gas or any other suitable source of inflation gas. Inflation source  14  is fluidically connected to inlet port  16  of aspirator  20  via a control valve shown schematically as reference  18  in  FIG. 1 . 
     Aspirator  20  comprises a housing  22 , which in the illustrative embodiment comprises an upstream portion  24  of substantially rectangular cross-section converging to a downstream portion  26  of substantially circular cross-section. Upstream portion  24  of housing  22  includes a plurality of check valves  28  comprising rectangular flaps that are hinged to allow the atmospheric air to flow into the interior volume  30  of housing  22  when the pressure in interior volume  30  is sub-atmospheric. Check valves  28  are biased toward the closed position to prevent air escaping interior volume  30  of housing  22  when the pressure in interior volume  30  is equal to or greater than atmospheric pressure. 
     Aspirator housing  22  can be constructed of any suitable material such as metal, plastic or the like, but in the illustrative example of  FIG. 1 , housing  22  is formed of a reinforced plastic. In typical installations, housing  22  is mounted to inflatable device  12  so that all or a substantial portion of housing  22  extends into the inflatable device  12  through an opening in the inflatable device  12  for that purpose. 
     Aspirator  20  may optionally be equipped with a slide valve  32 , which moves away from check valves  28  to allow them to open when the pressure in channel  34  is sufficiently high. When pressure in channel  34  falls below a pre-determined threshold indicating the inflatable device  12  is substantially near its full inflation pressure, spring  36  urges slide valve  32  against check valves  28  to lock them in their closed positions. 
     Aspirator  20  further comprises a nozzle assembly  40  comprising a plurality of individual nozzles  42  for directing high velocity jets of gas into the intake end  44  of aspirator barrel  46 . Aspirator barrel  46  comprises a plurality of tubular support members  48 , which in the illustrative embodiment are formed by attaching (e.g., stitching together or bonding) an outer sleeve  50  and an inner sleeve  52  to with a plurality of webs  56  which run in a longitudinal direction relative to a flow of gas through the inner lumen  54  of aspirator barrel  46 . 
     Outer sleeve  50 , inner sleeve  52  and webs  56  of aspirator barrel  46  are preferably fabricated from an air impervious material such a lightweight fabric that has been coated with an elastomer such as rubber or urethane. The various parts of the aspirator barrel  46  form a unitary composite structure capable of maintaining its shape during operation. The entire structure of the aspirator barrel  46  is preferable formed such that all of the chambers  56  comprising the structure are interconnected pneumatically, such that a single pressurized gas source may be utilized for its deployment. 
     Aspirator barrel  46  further comprises a conduit  58  which interconnects the chambers  56  of tubular support members  48  to nozzle assembly  40 . Conduit  58  preferably comprises an off-the-shelf reinforced elastomeric high pressure hose, but may be made of any suitable material capable of withstanding inflation pressures present in nozzle assembly  40 . For example, conduit  58  may comprise a reinforced fabric sleeve coated with an elastomer similar in construction to the tubular support members  48 . Aspirator barrel  46  is secured to housing  22  by means of a plurality of fabric loops  60  which are secured to the downstream portion  26  of housing  22 . Alternatively, aspirator barrel  46  may be attached to housing  22  by means of a dedicated flange similar in construction to flange  62  which secures housing  22  to the inflatable device  12 . 
     In operation, high pressure gas from inflation source  14  enters the aspirator through inlet port  16  and exits through nozzles  42  of nozzle assembly  40  into intake end  44  of aspirator barrel  46 . Simultaneously, high pressure gas from inflation source  14  flows from nozzle assembly  40  through conduit  58  into chambers  56  of aspirator barrel  46  causing aspirator barrel  46  to deploy from its stowed condition as shown in  FIG. 1  to its deployed condition as shown in  FIG. 2 . Because aspirator barrel  46  is exposed to the full inflation pressure present in nozzle assembly  40 , aspirator barrel  46  may be equipped with one or more pressure relief valves  62  to prevent overpressurization and consequential distortion or rupturing of aspirator barrel  46 . 
     The large ratio of nozzle periphery to cross-sectional area of nozzles  42  is sufficient to induce a flow of ambient air from interior volume  30  of housing  22  into inner lumen  54  of aspirator barrel  46 . This induced airflow will in turn cause the pressure in interior volume  30  and at least a portion of inner lumen  54  to drop below atmospheric pressure. The pressure of atmospheric air on the check valves  28  causes them to swing inwardly toward an open position, permitting the atmospheric air to enter housing  22  to become entrained with the high velocity flow of gas exiting nozzles  42 . 
     The multiple chamber structure of aspirator barrel  46  enables it to be substantially rigid and therefore to maintain the shape of interior lumen  54  notwithstanding the sub-atmospheric pressure and pressure fluctuation within interior lumen  54 . As shown in  FIG. 2 , in order for the induced flow of air to be sufficient to entrain substantial atmospheric air, the ratio of the length of the interior lumen  54  to its effective diameter is at least 1.0 preferably at least 1.5 and is typically between 1.5 and 3.0 for a maximum efficiency. (Because interior lumen  54  is not perfectly cylindrical, as used herein, “effective diameter” is the diameter of a circle of equal flow area, i.e., the cross-sectional area of interior lumen  54  divided by π). As noted herein, aspirator barrel  46  in its deployed condition is substantially rigid in that it is capable of maintaining the shape of inner lumen  54  in spite of sub-atmospheric pressure and/or pressure fluctuations in inner lumen  54  that would cause a flexible conduit to collapse and/or flutter, thus stalling the air stream and reducing the aspirator efficiency. 
     During the major portion of the operation of aspirator  20 , the jet stream flowing from the nozzles will have sufficient velocity to induce a flow of atmospheric air past check valves  28 . When, however, the pressure at the source is reduced and the velocity of the gas exiting the nozzles falls, back pressure from the inflatable device  12  will cause the check valves  28  to close. Since the pressure of the inflation source  14  will still be above the pressure in the inflatable device  12 , gas will continue to flow from nozzles  42  to increase the pressure in the inflatable device without the addition of any further entrained atmospheric air. The final pressure of the inflatable device then may be limited by providing various pressure relief valves or other devices to limit the final inflation pressure. 
     Although the illustrative embodiment of  FIGS. 1-4  contemplate inflatable tubular support members  48  which are longitudinal with respect to a flow of gas through inner lumen  54 , the present invention is not limited to a longitudinal support structure. An alternative embodiment as shown in  FIG. 5  contemplates a plurality of torroidal support members  68  supporting an inner sleeve forming the outer wall of lumen  74 . Torroidal support members  68  may comprise a plurality of individual torroidal support members interconnected by a common septum or may constitute a single helical torroid fluidically connected via conduit  58  to inflation source  14 . Additionally, as shown in  FIG. 6  the present invention is not limited to a collapsible aspirator barrel fabricated in entirely of fabric but may comprise a plurality of rigid supports such as hoops  82  formed of any suitable rigid material such as metal or plastic in combination with one or more fabric sleeves  84 ,  86  forming a structure that is inflated to expand from a stowed, collapsed condition to a deployed condition having sufficient rigidity to maintain the shape of interior lumen  88  as hereinbefore described. Finally, although the prior embodiments contemplate inflation of aspirator barrel  46  through a conduit  58  emanating from nozzle assembly  40 , any source of high pressure inflation gas may be utilized without departing from the present invention, for example, as shown in  FIG. 7 , an external conduit  92  leading directly to inflation source  14  may be incorporated in lieu of conduit  58  for providing pressurized gas for inflating aspirator barrel  94 . 
     Although certain illustrative embodiments and methods have been disclosed herein, it will be apparent from the foregoing disclosure to those skilled in the art that variations and modifications of such embodiments and methods may be made without departing from the invention. For example, although the illustrative embodiment of  FIG. 4  comprises a plurality of tubular members formed by stitching a plurality of webs between an inner and outer sleeve, as shown in  FIG. 8 , outer sleeve  102  may be stitched directly to inner sleeve  104  to form a plurality of longitudinal tubular members  106  without departing from the scope of the present invention. Accordingly, it is intended that the invention should be limited only to the extent required by the appended claims and the rules and principles of applicable law. Additionally, as used herein, unless otherwise specifically defined, the terms “substantially” or “generally” when used with mathematical concepts or measurements mean within ±10 degrees of angle or within 10 percent of the measurement, whichever is greater.