US 3460747 A
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rum NITRAT comaus'nou j PRODUCTS) 1/ com uoum REFRIGERANT uoumen FLUOR- HOT GASES (as. AMMON- E FIRST STAGE j i inf i 2 a x 4 91L ,1 MASS FLOW mom OBJECT 4 PRESSURE M PSIG (m A PRESSURE v sscorw STAGE a INATED HYDROCARBON) o NE H0 ET AE RYER G D OA SFGG WW NE 3% CAJL ATTORNEYS United States Patent 3,460,747 INFLATION METHOD AND APPARATUS Charles J. Green, Vashon Island, Alan K. Forsythe,
Seattle, John W. Goode, Mercer Island, and Lyle D. Galbraith, Redmond, Wash., assignors to Rocket Research Corporation, Redmond, Wash., a corporation of Washington Continuation-impart of application Ser. No. 678,565,
Oct. 27, 1967. This application Nov. 5, 1968, Ser.
Int. Cl. F04f 5/22, 5/48; F16k 15/20 US. Cl. 230-104 5 Claims ABSTRACT OF THE DISCLOSURE Gases under pressure are continuously delivered at a rate characterized by substantially no pressure droop into the first stage of a two-stage ambient air aspirator connected to a gas confining type inflatable, to serve as the aspirating fluid for the first stage. The first stage effluent is used as the aspirating fluid for the second stage and the second stage effluent is directed into the inflatable until it is substantially full. Thereafter, the ambient air path for the second stage is valved shut and the first stage effluent alone is used to complete inflation.
CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation-impart of our copending application Ser. No. 678,565, filed Oct. 27, 1967, and entitled Two Stage Inflation Aspirators.
BACKGROUND OF THE INVENTION Field of the invention This invention relates to inflation aspirators, and more particularly to multistage aspirators adapted for rapid inflation of various inflatable objects; such as escape chutes, rafts, and the like.
Description of the prior art A rapid inflation rate is a requirement of many inflatable devices, particularly those used with emergency objects, such as escape chutes and rafts.
Prior art aspirating devices aiming towards rapid in flation of inflatable objects have generally taken one of two forms. The first form is exemplified by the aspirator shown in the patent to Neigel, 2,859,908. An aspirating gas is introduced as a high velocity stream into a venturi nozzle adapted to discharge into the object being inflated. The upstream end of the nozzle is open to the surrounding air and the high vleocity gas stream creates a suction to draw or aspirate ambient air into the stream for the purpose of increasing its volume. When the object is sufliciently inflated, and delivery of the aspirating gas has ceased, a check valve in the nozzle is closed by back pressure to prevent deflation.
A second form of inflation aspirator is shown in the patent to Crawford et a1. 2,772,829. It is adapted for use in installations wherein the combined stream of aspirating gas and aspirated air, although of a high volume, is of an insuflicient pressure to fully inflate the object. A check valve is provided to be closed by back pressure when the pressure in the object being inflated reaches the pressure of the air and gas stream. Aspiration of ambient air is stopped. However, the gas flow is continued and it, by itself being of a higher pressure than the gases in the object, continues to inflate the object.
SUMMARY OF THE INVENTION This invention includes the technique of using a twoice stage aspirator to inflate a gas confining flexible-walled object. The aspirating fluid for the first stage is obtained from a constant pressure source and the stream of aspirating fluid and aspirated air leaving the first stage nozzle is used as the aspirating fluid for the second stage nozzle. In this manner a high volume, low pressure fluid stream is used to inflate the object up to a desired pressure level less than the final pressure. When this lower level is reached the second stage of the aspirator is fluid choked or valved shut and inflation is completed by the eflluent of the first stage nozzle only.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of a constant pressure gas source, a two-stage aspirator, and an inflatable object;
FIG. 2 is graphical illustration showing the pressureflow characteristics of the aspirator;
FIG. 3 is an isometric view of one form of two stage aspirator;
FIG. 4 is an axial section view of the aspirator of FIG. 3, both stages active;
FIG. 5 is an axial section of such aspirator with only the first stage active;
FIG. 6 is an axial section view of another form of two-stage aspirator; and
FIG. 7 is a cross-sectional view of the aspirator shown by FIG. 6.
DESCRIPTION OF THE PREFFERED EMBODIMENTS Referring to FIG. 1, a stream of hot gases (e.g. the products of combustion of an ammonium nitrate type solid fuel grain) and a stream of a cold liquid refrigerant (e.g. a pressure liquified fluorinated hydrocarbon) are separately and continuously introduced into a mixing chamber M for flow through mixing. In chamber M the refrigerant is vaporized with the heat of vaporization being supplied by the hot gases. A high pressure, relatively cool, gaseous effluent leaves chamber M and is the primary or aspirating fluid for the aspirator 10. The pressure of such cool fluid is dependent on the delivery rates of the hot gases and the refrigerant. According to the invention the hot gases and the refrigerant are delivered at constant or progressively increasing rates, so that the inflating fluid never experiences a pressure droop. A progressive increase in the flow rates causes a progressive increase in the pressure of the working fluid tending to enter the inflatable in opposition to a progressively increasing back presure.
Cool gas generators for generating and supplying a no droop aspirating fluid for the first stage are disclosed in copending applications Nos, 608,152 and 682,730, respectively filed on Jan. 9, 1967 and Nov. 7, 1967. Application Ser. No. 608,152, issued as US. Patent No. 3,431,- 742 on Mar. 11, 1969. Application Ser.. No. 682,730 issued as US. Patent No. 3,431,743, also on Mar. 11, 1969. The disclosures of these patents are hereby expressly incorporated herein by this specific reference.
The aspirating fluid is discharged through a plurality of orifices 17 into a first stage nozzle 18, the downstream end of which is initially closed by a circular inner check valve 20. A second stage nozzle 22 is positioned downstream of the first stage nozzle and has an air intake opening closed :by an annular outer check valve 24. The gas streams discharging from the orifices 17 entrain air into the first stage nozzle 18. The effluent of the first stage nozzle flows into the second stage nozzle 22 and becomes the aspirating fluid for the second stage. Inflation takes place at a rapid rate due to the high volume of air discharged from the second stage. When the pressure builds up in the object O (cg. an escape U slide) to a predetermined level, the outer check valve 24 is closed by back pressure and the object is further inflated by the first stage nozzle 18 alone. When the object is fully inflated, gas flow is ceased and the back pressure in the object closes the inner check valve 20 as well, and the two valves 20, 24 together prevent deflation.
The first stage nozzle 18 has a cylindrical throat 26 formed integrally with a smoothly rounded, diverging flange 28 that defines an air inlet 29. The inlet manifold 15 extents diametrically across the air inlet and is secured to the flange to provide structural strength. The orifices 17 are aligned diametrically on the downstream Side of the manifold.
The second stage nozzle 22 includes a cylindrical throat 3t integrally formed with a rounded, outwardly diverging inlet flange 32 that defines a second air inlet 33. An annular mounting ring 34 is secured to an inlet flange and is secured to the fabric 38, or the like, of an object to be inflated, such as an airplane escape chute, for example. The second stage nozzle is connected to the first stage nozzle by three equidistantly spaced structs 40 that are secured, as by welding, to the second stage inlet flange and the outside surface of the first stage nozzle throat 26. The inlet flange 32 is provided with an inwardly directed peripheral lip 42 that serves as a valve seat in a manner to be hereinafter described.
The inner check valve 20 is best shown in FIG. 3 and includes a circular member or flap 44 of neoprene, rubber, or other flexible, resilient material, and is of a diameter slightly greater than the inside diameter of the throat 26. A pair of centrally bored bosses 46 are bonded or otherwise secured to the downstream surface of member 44 and are aligned along its vertical diameter. The bosses receive a pin 48 which is secured in spaced holes by any suitable means, in the throat 30 of the second stage nozzle 22. The pin serves as a support about which the side segments of the member 4 may pivot.
A pair of semi-circular strengthening members 52 are secured, as by bonding, to each side of the downstream surface of the member 44. These members 52 are preferably of aluminum or any other suitable relatively rigid material. Each member 52 extends radially outwardly almost to the peripheral edge of the member 44. In effect, the check valve amounts to two hinged together rigid flaps with a resilient peripheral sealing edge,
The outer check valve 24, which closes off the second air inlet 33, includes an annular resilient, flexible member 54 of the same flexible material as the circular member 44. A pair of centrally bored bosses 56 are bonded to the downstream surface of the annular member 54. The bosses are diametrically aligned and receive the pin 48. A pair of semi-annular strengthening members 58 are secured, as by bonding, to the downstream surface of the member 54 and extend almost to the inner and outer edge of such member 54. These members 58 function in the identical manner as the members 52. The upstream outer peripheral edge 60 of the member 54 abuts against the lip 52 of the inlet flange 32. The inner edge 62 of the member 54 extends radially inwardly beyond the inner circumferential surface of the throat 26 of the first stage nozzle 18 and serves as a seat for the inner valve 20.
When air in being aspirated in both stages, the side parts of the annular member 54 are folded together downstream. As the object is filled a back pressure is developed, and eventually it closes the annularvalve member 54 and the second stage of the aspirator ceases to operate. Inflation is then completed by the primary aspirator alone. Following completion of the inflation the inner circular valve member 44 is also closed by back pressure and it and the annular valve 24 function together as check valves to hold the fluid in the object.
The effect of the two-stage aspiration is best shown in FIG. 2, wherein the line ABD represents the flow rate of the combined first and second stages if no second stage shutoff valve were to be provided. The lines shown in the graph of FIG. 2 actually represent a mass flow ratio a constant flow of aspirating fluid i t As an example, assume the aspirating fluid source produces a supply of aspirating fluid fu at a constant rate of one pound mass per second. If the second stage is being used, that is as indicated by the line ABD the initial mass flow rate of aspirated air is at a ratio of 3.2 and thus is 3.2 l pound mass per second yielding a total fluid flow rate of approximately 4.2 pounds mass per second. At a ratio of 1 along the same line ABD the aspirated air flow rate is also 1 pound mass per second so that total flow rate at this ratio is 2 pounds mass per second. This convention of referring to flow rate rather than to ratio will be followed that a high volume of mixed air and gas is initially introduced into the object but that pressure never exceeds 2 p.s.i.g. In the embodiment just described, the area of the air inlet of the combined nozzle stages is approximately 4 /2 times the area of the air inlet of the first stage nozzle alone.
The line EBC represents the flow rate if only the single stage were to be used, as was heretofore customary, The single stage can reach a significantly greater pressure. However, the initial flow rate is substantially less than with two stages.
By the use of the check valve 24 in the second stage nozzle 22 the flow rate curve follows the solid line ABC. Thus, a high volume initial flow rate is produced up until point B where the back pressure is suflicient to close the outer check valve 24. The curve then follows the flow rate for the single stage nozzle reaching a pressure of over 4 p.s.i.g. in the example presented. Since the first 60% of inflation is at a pressure slightly greater than atmospheric, the large volume will greatly increase the speed at which this amount of inflation is reached, For example, in the installation to which the graph relates the initial use of the second stage reduced the timeof filling from 5 to 3 seconds or a percentage increase of Aspirator 70 shown by FIGS. 6 and 7 comprises first and second stages 18, 22, respectively. The first stage includes a tubular nozzle 26 and an injector 15' for the aspirating fluid. Pipe 16' is connected to the mixing chamber M. The tube 26 is situated inside a larger and longer tube 30. Three evenly spaced radial support plates 72 rigidly interconnect the tubes 26', 30.
The check valve for the annular second stage path comprises a cylindrical sleeve 74 of rubberized fabric or the like. Sleeve 74 is attached at its outer end 76 t0 the outer end of tube 30'. The support plates 72 are secured to the tube 30', such as by welding at points 78. The plates 72 are cut away in the region of the seal member 74, so that in each of such regions the member 74 is clamped between an outer radial end surface of the members 72 and a contiguous inner portion of the Wall 30.
During second stage aspiration a sleeve 74 is generally cylindrical in form and closely hugs the inner surface of the tube 30'. When back flow commences, the strongest flow is relatively along the inner surface of wall 30'. It catches the loose downstream edge portions of the member 74 between the support plates 72 and moves such edge portions radially inwardly. Pockets are formed circumferentially between the plates 72 and radially between member 74 and tube 30'. The forward ends of the pockets are closed by virtue of the all-around connection of the member 74 to the tubular wall 30' at 76. The back flowing gases fill up the pockets. As shown by broken lines in FIGS. 6 and 7, the back flowing fluid causes the member 74 to move in and closely hug the outer surface of inner tube 26'. Since the pressure in the pockets acts in all directions the portions of member 74 on opposite side of the support plates 72 are pressure held against the support plates 72.
The circumferential lengths of the portions of member 74 which hug the inner tube 26' plus the radial lengths of the portions of member 74 which hug the supports 72 all together substantially equal the circumferential length of member 74 when it is out against the outer tube 30'. This is because the circumference at the inside wall of tube 30' is greater than the circumference at the outer surface of tube 26' by an amount equal to 21r times the difference in radius at these two locations, i.e., the difference in circumference is 6.28 times the difference in radius. The amount of material required to hug both walls of each of the three struts 72 is equal to 6 times the difference in radius. There is a slight excess of circumferential length in the material 74 which is equal to 6.28 times the difference in radius, i.e., the radial length of the member 72. This excess length is distributed about the outer surface of tube 26' and is easily accommodated so that a substantial tight fit exists between the inner surface of member 74 and the outer surface of tube 26' between the struts 72, and the two side surfaces of the struts 72.
In this form the tube 30 is manufactured to include a circumferential shoulder 80. A single large check valve 82 is supported in the tube 30' generally in a common plane with the downstream surface of shoulder 80. The valve 82 is supported by a support pin 84 which extends across, and is anchored at its opposite ends to, the tube 30'. A transverse stop pin 86 may be provided downstream of pin 84 in the same axial plane with pin 84. When valve 82 is closed its peripheral region abuts the radial downstream surface of shoulder 80. Check valve 82 functions like check valve 20 in the embodiment of FIGS. 3-5, and also serves to prevent leakage from the object 0 once it has been inflated.
What is claimed is:
1. In combination:
an inflation aspirator comprising an inlet tube of said inflatable for a gas confining type inflatable having an ambient air inlet and a combined fluid outlet, an injector for delivering an aspirating fluid into said inlet tube, and the improvement characterized by tubular wall means dividing the interior of the inlet tube into first and second stage passageways, each having an ambient air inlet, with said injector being positioned to discharge directly into the first stage passageway, and with said first stage passageway being positioned to discharge into said second stage passageway, so that the mixture of aspirating fluid and aspirated ambient air discharging from said first stage passageway functions as an aspirating fluid for causing second stage aspiration in the second stage passageway, and check valve means in an ambient air inlet portion of said second stage passageway, arranged to close in response to a predetermined back pressure in the inflatable and in that manner render the second stage of the aspirator ineffective, with inflation thereafter being completed by the first stage of the aspirator along;
a source of primary aspirating fluid comprising a gaseous fluid eminating reaction chamber, and means for controlling the efiiuent pressure from said reaction chamber so that such eflluent experiences no pressure droop; and
means for continuously delivering such effluent to said injector to serve as a no pressure droop primary aspirating fluid stream.
2. In an inflation system for a gas confining type inflatable, the method of delivering a cool gas energy stream at a rate of flow characterized by substantially no pressure droop, into an ambient air aspirator connected to the inflatable, to pump air into the inflatable, and after the inflatable is partially distended, disabling at least a portion of the aspirator while continuing to deliver the generated cool gases into the inflatable without pressure droop, to complete distention of and pressurize the inflatable.
3. In an inflation system for a gas confining type infiatable, the method of continuously delivering a stream of cool gases under pressure into the first stage of a two-stage ambient air aspirator discharging into an infiatable, and using the stream of such cool gases combined with the ambient air entrained into said first stage as the pumping fluid to operate the second stage of the aspirator during at least most of the time the inflatable is being filled, and then rendering the second stage of the aspirator ineffective responsive to pressure within the inflatable, and pressurizing the inflatable to the extent desired by continuing to deliver the cool gases through the first stage of the aspirator without pressure droop.
4. A method of inflating an object comprising the steps of:
directing a stream of an aspirating fluid generally axially through a first stage nozzle which about said stream is open to ambient air, to entrain ambient air into said nozzle; directing the effluent of the first stage nozzle axially through a second stage nozzle which at least partially about said first stage nozzle is open to ambient air, and is arranged to discharge into an inflatable object, for the purpose of entraining an additional quantity of ambient air into the second stage nozzle;
ceasing second stage entrainment of ambient air substantially when the back pressure in the object equals the pressure of the second stage ambient air stream;
completing inflation of the object by use of the entraining fluid and the first stage entrained ambient air stream alone; and
closing all avenues through the nozzles once inflation has been completed.
5. The method of claim 4, comprising automatically closing said avenues by back pressure closure of check valve means in the nozzles.
References Cited UNITED STATES PATENTS 1,367,208 2/1921 Schmidt 103-258 2,096,226 10/1937 Crosthwait 230-92 2,296,122 9/1942 Squassoni 230-45 2,399,670 5/1946 Preggang 230-92 2,887,120 5/1959 De See 137-223 3,042,290 7/ 1962 Fraebel 230-95 3,204,862 9/ 1965 Hadeler 230-95 3,338,266 8/1967 Zilka et a1. 103-263 X 3,358,909 12/1967 Mansson et al 230-45 3,370,784 2/1968 Day 137-223 X 3,395,647 8/1968 Clabaugh 103-272 X DONLEY J. STOCKING, Primary Examiner W. J. KRAUSS, Assistant Examiner US. Cl. X.R.