US3771913A

US3771913A - Aspirator

Info

Publication number: US3771913A
Application number: US00144512A
Authority: US
Inventors: J Macpherson; P Serbu
Original assignee: Susquehanna Corp
Current assignee: Susquehanna Corp
Priority date: 1971-05-18
Filing date: 1971-05-18
Publication date: 1973-11-13
Anticipated expiration: 1990-11-13

Abstract

Embodiments of inflation aspirators are disclosed which use the pressure of the primary, high-pressure gas source to open and close the aspirator housing. The closure is connected to a piston/cylinder arrangement. The cylinder and piston undergo relative axial movement in response to application of the primary gas to open the closure to permit entrainment of ambient air. Once inflation is complete, the primary source terminates. A reservoir within the aspirator traps sufficient gas at pressure to effect reverse relative movement of the cylinder and piston to close the closure and seal the housing.

Description

United States Patent 91 MacPherson et al.

[ Nov. 13, 1973,

ASPIRATOR- Inventors: James R. MacPherson, Falls Church; Paul W. Serbu, Vienna, both of Va.

[73] Assignee: The Susquehanna Corporation,

Fairfax County, Va.

[22] Filed: May 18, 1971 [21] Appl. No.: 144,512

US. Cl. 417/179, 417/184, 417/191 1 [51] Int. Cl. F04f 5/46, F04f 5/48 [58] Field of Search 417/179, 184, 191,

[56] References Cited UNITED STATES PATENTS 3,042,290 7/1962 Fraebel 417/191 3,572,974 3/1971 Day 417/191 UX 3,591,314 7/1971 Day ..417/191UX 3,598,504 8/1971 Siravo 417/191 X Primary Examiner-Carlton R. Croyle Assistant Examiner-Richard E. Gluck Attorney-Burton L. Lilling et al.

[57] ABSTRACT Embodiments of inflation aspirators are disclosed which use the pressure of the primary, high-pressure gas source to open and close the aspirator housing. The closure is connected to a piston/cylinder arrangement. The cylinder and piston undergo relative axial movement in response to application of the primary gas to open the closure to permit entrainment of ambient air. Once inflation is complete, the primary source terminates. A reservoir within the aspirator traps sufficient gas at pressure to effect reverse relative movement of the cylinder and piston to close the closure and seal the housing.

21 Claims, 6 Drawing Figures PATENIED NOV 13 I973 SHEET 10F 4 INVENTORS JAMES A MK'Pf/E/PSON 9404 W JEpau i A RNEY ASPIRATOR BACKGROUND OF THE INVENTION structures are of considerable size and extent when in' use, it will be apparent that a considerable volume of air and/or gas is required to inflate them.

The prior art generally provides such inflatable struc tures with aspirators to aid inflation together with a source of gas. These gas sources include such things as compressedair cylinders as well as gas generators. In view of space and weight limitations normally encountered, these gas sources can supply only a limited volume of high-pressure gas. By the use of an aspirator, this high-pressure gas acts to draw or entrain ambient air into the aspirators and thus into the inflatable structures. Accordingly, a small volume of high-pressure gas can effect the introduction of a large volume of relatively low-pressure gas and air into the inflatable structures to the extent required for inflation.

Aspirators of the prior art normally include a valve or closure in the aspirator passageway which opens at the beginning of the inflation cycle, and closes at or near the end of such cycle to prevent the escape of gas from the inflatable structure. Such valves usually depend for their operation upon the pressure of the supply gas, as in the case where the valve mechanism is actuated by a piston, or on differential pressure induced by flow of the primary supply gas. It is quite common to put the valve member at the outlet end of the aspirator which, by opening into the inflatable structure, may hinder the unfolding and erection of the inflatable structure. In such case, special housing or guard means may be required and such can adversely affect the perforrriance efficiency of the aspirator. For those aspirators which use a piston-actuated valve, the return of the piston at the end of the inflation cycle is accomplished by means of a compressed spring once the primary gas supply pressure tails off or terminates. The reliability of the valve to close and remain closed may depend solely on the reliability of this spring. In the case of flapper A valves which are often placed at the aspirator inlet, they are sensitive to the back pressure within the inflatable structure and close when the back pressure reaches a predetermined level. However, in such case, the primary gas flow continues and must be relied upon to complete inflation and harden the inflatable structure. Unless auxiliary check valves or dump valves are provided as a safety feature, the structure can overinflate and perhaps be weakened or actually rupture.

SUMMARY OF THE INVENTION to the pressure of the primary gas source and is actuated by a novel piston and cylinder arrangement and a gas reservoir which stores a free volume of the primary gas. As long as the primary gas is being applied to the aspirator, the closure remains open to permit entrainment of ambient air for rapid inflation of the inflatable. Should the inflatable structure attain its designed pressurization before the primary source terminates, the open closure permits back-flow to prevent inflation past the designed pressure. level. Once the primary source terminates, the gas stored in the reservoir acts upon the piston and cylinder to effect a relative axial movement of these two members and a retraction of the closure into its closed position. In the preferred embodiments shown herein, this closure is placed at the inlet end of the aspirator so that it will not interfere with the unfolding or inflation of the inflatable structure or require additional housing to avoid such interference.

It is an object of the present invention to provide an improved aspirator having a novel closure-actuating mechanism which permits a prompt and positive sealing of the aspirator passageway following inflation of the inflatable structure.

A further object of this invention is to provide such an aspirator which is efficient in operation and capable of providing high entrainment ratios of ambient air flow to primary flow.

Another object of the present invention is to provide such an aspirator which effects a rapid inflation and hardening of the inflatable structure and is capable of accommodating back-flow to avoid over-pressurization of such structure.

A still further object of the present invention is to provide such an aspirator which has a plurality of nozzles for directing the primary gas into the passageway of the aspirator, such nozzles being arranged to provide high mass flow rates of primary gas and entrained air into the inflatable structure.

Still another object of the present invention is to provide such an aspirator in which the closure is placed adjacent to the inlet end of said passageway and designed to extend axially out from the inlet end of the aspirator, thereby avoiding any hindrance to the unfolding and inflating of the inflatable structure while providing a clear opening for admission of ambient air.

Still another object of the present invention is to provide such an aspirator which is lightweight and compact in construction yet provides excellent entrainment and mixing of the ambient air with the primary flow resulting in efficient and rapid inflation of the inflatable structure. 1

Other objects and advantages of the present invention will become apparent from a reading of the following specification in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS embodiment of FIG. 1 in longioperation of the aspirator;

FIG. 4 is a view of a second embodiment of the present invention in longitudinal cross-section; and

FIG. 5 is a view of the aspirator of FIG. 4 taken along lines 5 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference now to the drawings and more particularly to FIGS. 1 and 2, the aspirator is shown as having an elongated, tubular housing 10, the interior of which defines a passageway 12 for the flow of gas and/or air therethrough. Housing has an inlet end 14 and an outlet end 16. Tubular housing 10 is here shown as being of a generally cylindrical construction, flaring slightly towards its outlet end 16 to provide the passageway 12 with a diffuser portion.

A cone-shaped closure 18 is positioned adjacent to the inlet end 14 of the passageway 12 and is designed to open and close along the longitudinal axis of the asp'irator. An adapter fitting 20 is centrally attached to closure 18 for communicating with a pressurized gas supply, hereinafter called primary gas. This gas is preferably supplied via a flexible hose 22, and fitting 20 is preferably formed with an angular bend as shown so that the hose 22 will not interfere with the opening and closing of closure 18.

The outer annular face 24 of the closure is flattened to fit within passageway 12 when closed and contact the inner surface 26 of housing 10. This fit is not an overly tight one so that the movement of closure 18 is not restrained; however, an O-ring 28 is seated within an appropriate groove formed in the face 24 of closure 18, and this O-ring is compressed by the inner surface 26 when closure 18 is in the closed position so that an air-tight seal within passageway 12 is provided at the closure.

Closure 18 is supported within housing 10 by a spider which includes an elongated tube 30 and three equally spaced supports 32 which centrally position the tube 30 within the passageway 12. Supports 32 of the spider are preferably of a thin construction'so as not to create any undue resistance to the flow of gas and air through passageway 12. The spider can be mounted in the passageway 12 by any suitable means such as by welding the supports 32 to the inside surface 26 of the passageway or by set screws which are inserted through the housing 10.

With reference particularly now to FIG. 2, the internal construction of closure 18 and tube 30 can be clearly seen. Closure 18 has essentially a hollow center which is threaded at its forward end to receive threaded fitting 20. A nut 34 holds this fitting securely in place on the closure. The hollow interior of closure 18 defines a chamber 36 which is in open communication with the passage through fitting 20. Extending radially outwardly from chamber 36 is a plurality of narrow passageways 38 which can be drilled or otherwise formed in closure 18 during manufacture. Each passageway 38 is provided with a plurality of spaced aperatures 40 aligned in a downstream direction. Each aperture 40 is threaded to receive an elongated,

tubular nozzle

42a, 42b, or 42c. Each nozzle, in effect, is an extension of the aperture 40 to which it is connected and, with regard to a particular passageway 38, is of a length so as to direct the primary gas into the passageway 12 of the aspirator at a different downstream point from the other associated nozzles. The purpose for this will be explained more fully hereinafter.

Positioned within tube 30 is an elongated cylinder 44 which extends substantially the entire length of this tube. At its upstream end, tube 44 terminates in a threaded boss 47. This boss mates with closure 18 adjacerlt to the chamber 36. As a result, cylinder 44 and closure 18 move as a unit.

Disposed within cylinder 44 is an elongated rod 46. This rod 46 at its one end extends past the end of cylinder 44 and through a hold 48 formed in the bottom of tube 30. This one end of rod 46 is threaded and is secured to tube 30 by nut 50. The other end of rod 46 is provided with a flange 52 which positions an annular piston seal 54. This end of the rod 46 is also threaded and mates with a threaded cup-shaped member 56 whose face abuts seal 54 to retain it in place.

As described, rod 46 functions as a piston within the cylinder 44, this piston and cylinder being designed for relative movement along their common longitudinal axis. Piston 46 is stationary by virtue of being secured to tube 30, but cylinder 44 is free to move. By the movement of this cylinder, closure 18 can be extended from a closed to an open position and retracted to a closed position, all as more fully explained hereinafter.

Piston 46 and cylinder 44 are restrained against relative motion by a ball-lock mechanism. To this end, the cup-shaped extension 56 of piston 46 slidably receives a spring-loaded member 58 which is urged outwardly by a small spring 60. The forward end of valve 58 is twice reduced in diameter to form two

neck portions

62 and 64. A pair of steel balls 66 abut the neck 62 when the mechanism is in locked position, as shown. These balls 66 also lie within holes 68 formed in the wall of member 56 and abuts the surface of an internal annular groove 70 in boss 47 of cylinder 44. As long as the valve 58 remains in the position shown, balls 66-remain in mating relationship with neck 62, holes 68 and groove 70 to lock the cylinder 44 to piston 46.

Spaced downstream from flange 52 on piston 46 is a second flange 72.

Flanges

52 and 72 and the rod portion of piston 46 therebetween define an annular chamber 74 within cylinder 44. A rubber bumper 76 is positioned on the down-stream shoulder of flange 72. Cylinder 44 is closed at its downstream end by nut 78. O- ring 80 is provided to seal this lower end of the cylinder against piston 46. End face 82 of this nut is designed to abut bumper 76 to limit axial travel of cylinder 44 and thereby the extension or opening of closure 18.

Housing 10 is here shown as divided into two

sections

84 and 86. This division is through flange 88 to permit the aspirator to be attached to the inflatable 90, the latter being provided with a properly sized aperture for this purpose. The aspirator is secured to the fabric by a plurality of nuts and .bolts 92 or any other suitable means.

The operation of the embodiment shown in FIGS. 1 and 2 will become clear by reference to FIGS. 3a and 3b which show two stages in the inflation ycle. The flexible hose 22 through'which high-pressure primary gas is supplied to the aspirator isconnected to a gas source such as a compressed air bottle, gas generator, or other,

source suitable for use in an inflation system utilizing the present invention. These sources are preferably designed to rise immediately to their full operatingpressure since this lends to rapid inflation of the inflatable.

When primary gas is introduced into the aspirator via fitting 20, the pressure in chamber 36 and in

passageways

38 and 40 and nozzles 42 follows that of the primary gas source. Gas begins to be ejected from the r'estricted nozzles 42 downstream into passageway 12 of the housing in high-velocity streams. At the same time, the increase in pressure in chamber 36 causes member 58 to overcome the force of spring 60 and bottom within cup-shaped member 56. Balls 66 new ride inwardly off of neck 62 to neck 64. While these balls do not fall free into chamber 36, this movement is sufficient to clear groove 70 in the cylinder 44 and unlock the cylinder 44 for axial movement.

It should be pointed out that the fit between the cylinder 44 and those portions of piston 46 which slidably engage its inside surface does not form a seal, but instead provides sufficient clearance for gas flow. Thus, the pressure within chamber 36 causes gas flow around ball 66, over the outside surface of cup-shaped member 56, past seal 54 and flange 52, and into chamber 74. From there, gas flows past flange 72 and bumper 76 into the downstream annular chamber of thecylinder and piston combination. Thus, there is a pressure rise in these portions of the aspirator, also; however, the pressure rise downstream of bumper 76 cannot create a force sufficient to retard the opening force of cylinder 44 created by the high pressure within chamber 36 and also the fact that this pressure acts upon a greater cross-sectional area. Seal 54 is constructed as a oneway seal which permits air flow and thereby pressurization within the cylinder downstream of this seal but which expands and seals off this downstream end later when the pressure in chamber 74 exceeds that in chamber 36.

,With cylinder now unlocked, the force created by the high pressure in chamber 36 causes cylinder 44 to slide immediately to its full position as shown in FIG. 3b, this axial motion being limited by end face 82 of nut 78 striking bumper 76. Closure 18 is thus extended to its full open position, as shown. With high velocity air now being injected into passageway 12 by all of the nozzles 42, a large volume of ambient air, as represented by arrows 100, is entrained by this primary gas flow into passageway 12 where it mixes with the primary gas and flows out of the outlet '16 to inflate the inflatable. The aspirator is designed to provide a large mass flow of air and gas through passageway 12 into the inflatable so that inflation is rapidly accomplished.

The absence of any obstruction to air flow at the inlet end 14 of the housing affords a full 360 annular openhigh pressure throughout the inflation cycle and then end abruptly or tail off very quickly to terminate all gas flow. In the present invention, as long as the gas source remains at its operating pressure, closure 18 remains open; and the primary gas flow'entrains ambient air into the inflatable. However, should primary flow continue even after the inflatable has reached its inflation design point, as for example 3 psig, further flow of gas and air into the inflatable will be matched by a backflow which, by virtue of having the closure 18 in an open position, prevents damage or rupture of the inflatable from occurring.

When primary gas flow ends, the pressure within chamber 36 and the extended forward end of cylinder 44 drops to essentially atmospheric pressure. However, seal 54 prevents decay of pressure within chamber 74 because the pressure on the downstream side of this seal 54 is now greater than that of the upstream side, and it expends to seal off this downstream space. This reservoir of high-pressure gas within chamber 74 exerts a'force upon the cylinder 44 through end face 82 which drives the cylinder back to its initial position, thereby retracting closure 18 and sealing passageway 12. The aspirator now is in its initial position represented by FIG. 2.

The gas within reservoir 74, of course, distributes itself within the annular space downstream of bumper 82 as the cylinder is retracted. However, the positive closing force exerted on cylinder 44 is sufficient to maintain closure 18 closed against any'back pressure exerted by the inflatable. As a safety feature, it should be noted that upon retraction of cylinder 44, holes 68 will again become aligned with groove 70 in the cylinder. The absence of pressure in chamber 36 permits the spring-biased valve 58 to move outwardly driving balls 66 up onto neck 62 and into holes 68 and groove 70. Once again, the cylinder 44 is locked against outward movement.

The arrangement of the nozzles 42a, b, c, as shown in FIGS. 1 3, .have been found to provide, a marked increase in the mass flow of entrained ambient air. As shown more clearly in FIG. 3b, the outboard nozzles 42a actually extend down from the closure into passageway 12 while the inboard nozzles 42c extend just past the inner surface of closure 18 into the flow path. The middle nozzles 42b terminate at a point about halfway between the ends of

nozzles

42a and 42c; This arrangement is believed to cause a smooth flow along the flow surfaces with no boundary layer separation against either the wall of passageway 12 or the inner surface of closure 18. Furthermore,by staggering the nozzle ends as shown, 'all of the noz zles'and particularly the inner nozzles 42b and 420, have an entrainment flow path for the ambient air which is not obstructed by gas flowing out of an outer nozzle. Thus, the entire annular opening is utilized as a source of entrained air, and the entrainment action is maximized accordingly.

The foregoing nozzle arrangement leads to a more efficient aspirator performance resulting from the higher entrainment ratios attained. Such permits a reduction in the amount of primary gas which is needed and thereby the utilization of smaller primary gas sources. This is a result which is highly desirable where weight and size limitations are critical. The higher mass flow ratios which are attained can result in the inflation of large structures in the span of several seconds. This is a feature which is highly desirable where the inflatable structure is designed for use under emergency conditions, or deployment under conditions of high wind velocity where rapid erection will minimize shifting by the wind.

-lar housing 1 10, the interior of which defines a passageway 112 for the flow of gas and/or air therethrough. Housing 110 has an inlet end 114 and an outlet end 116. Tubular housing 110 is again shown as being of a generally cylindrical construction and flaring slightly toward its outlet end to provide the passageway 112 with a diffuser portion. Adjacent the inlet end of the aspirator housing 110 is an internally threaded boss 118 to which is attached a hose 120 to provide the aspirator with a primary pressurized gas supply.

Below boss 118 the housing 110 is provided with an inner annular shoulder 122. A spider 126 is mounted on this shoulder 122 and'is retained there by a conventional split retaining ring 124. With reference also to FIG. 5, which is a view taken along line 5 of FIG. 4, spider 126 is seen as being of generally wheel-like construction having a center hub 128 and a plurality of radial spokes 130 extending outwardly and terminating at a rim 134. In this figure, nine spokes are shown although it is obvious that a greater or lesser number can be used.

Each of the spokes 130 has a central passageway 132 which communicates at its inner end with the interior of the hub 128 and at its outer end with the hollow portion of rim 134. The rim 134 abuts the inner surface of housing 1 such that its hollow interior forms with this surface an annular passageway 136 which functions as an inlet manifold to distribute the primary gas applied at boss 118 to all of the passageways 132 in the spokes 130. Each of these passageways 132 opens into a plurality of apertures 138 formed in the spokes 130. Each aperture 138 functions as a nozzle which directs or ejects the primary gas into passageway 112 during the inflation cycle.

An elongated tube 140, closed and tapered at its downstream end, is secured to hub 128 by means of a threaded coupling and depends therefrom within passageway 112. Tube 140 houses the combination of piston 144 and cylinder 146 and provides a pressure chamber 142 at its closed downstream end. Cylinder 146 is supported by inner shoulder 148 of tube 140 and is secured against forward movement by its abutment against the interior shoulder 149 ofhub 128.

As shown, cylinder 146 is concentrically mounted in tube 140 but slightly spaced from its interior surface. This arrangement forms an annular passageway 150 which communicates at its upstream end with the spoke passageways 132 and downstream with chamber 142. The lower ends of piston 144 and cylinder 146 do not seal the tube and therefore the pressurized primary gas can flow from this annular passageway ,150 into chamber 142. However, if desired, several holes such as shown at 168 and 170 can be respectively placed in the cylinder 146 and cup-shaped member 152 to ensure rapid pressurization within chamber 142 of the tube at the commencement of the inflation cycle.

Piston 144 is free to slide within cylinder 146 but is initially restrained by a locking mechanism constructed in essentially the same manner as that of the first embodiment described hereinabove. As shown, piston 144 has a cup-shaped extension 1 52 at its lower end which slidably receives a spring-loaded member 154 biased outwardly by a small spring 156. The forward end of member 154 is twice reduced in diameter to form two

neck portions

158 and 160. A pair of steel balls 162 abut the neck 158 when the mechanism is in locked position. Each ball 162 lies within a hole 164 formed through the wall of member 152 and abuts the surface of an internal annular groove 166 formed in cylinder 146. As long as valve 154 remains in the position shown, balls 162 will remain in their mating relationship with neck 158, holes 164, and groove 166 to lock the piston 144 to cylinder 146.

Upstream of member 152, the piston 144 is provided with a small shoulder 172. Retained between this shoulder 172 and the end face 174 of member 172 is a hardrubber bumper ring 176 arranged in tandem with an annular piston seal 178. Although piston 144 is mounted to slide within cylinder 146, the fit is a loose one, and none of the piston components such as member 152, bumper ring 176 and seal 178 are in a sealed relationship with the cylinder. Thus, primary gas can flow at the commencement of the inflation cycle in the space between piston 144 and cylinder 146 to pressurize the reservoir upstream.

At its upstream end, piston 144 passes through a hole 177 in hub 128 where O-ring 179 maintains a gas-tight seal. Piston 144 terminates as an enlarged cup-shaped extension 181 which rests on top of hub 128. Piston 144 has a central passageway 180 drilled partly therethrough. This passageway 180 opens at its lower end through two apertures 182 into an annular chamber 183 defined by piston 144 and cylinder 146. The forward end of passageway 180 opens into a closed chamber 184 defined by cup 181 and cover 186. This cover is screwed onto cup 181 and sealed by O-ring 188. Chamber 184 functions as a gas reservoir for storing pressurized primary gas.

Cover 186 also retains a closure 190 onto the upstream end of piston 144. Closure 190 is constructed as a cap having a downwardly directed annular flange 192 at its periphery. The inner surface of flange 192 is flattened and smooth and designed to fit the outer surface of housing at the inlet end 114 of passageway 112. The fit between cap 190 and the housing 110 is not an overly tight one so that the opening of this closure is not restrained; however, an O-ring 194 is seated within an annular grooveformed in the outer surface of housmg 110, and this O-ring is compressed by the inner surface of flange 192 when closure 190 is in the closed position so that an air-tight seal within passageway 112 is provided. By virtue of having closure 190 secured to piston 144, the two move as a unit and closure 190 can be extended from a closed to an open position and retracted to a closed position during axial movement of this piston, all as more fully explained hereinafter.

The cap 190 is contoured as shown at 196 to provide in the open position a streamlined surface to the flow of entrained ambient air. Because this part of closure 190 extends downstream into the passageway 112 while in the closed position, it must be cut away where necessary, e.g., as shown at 198, to clear the spokes of spider 126. A fairing 200 is provided at the inlet end 114 of the passageway 112 also to provide a smooth and contoured surface to the flow of entrained ambient air. Fairing 200 is constructed as a flexible ring which is retained by a snap-fit onto housing 110. Fairing 200 is also cut away at a plurality of points such as shown at 202 so that it can bridge or clear the spokes 130 of spider 126.

The body of housing 110 is shown here as having essentially a one-piece construction. It is provided toward the inlet end with a downwardly directed flange 204 having an annular slot on its outer face. This arrangement permits the attachment of an inflatable 206 by securing it to flange 204 through the use of a conventional ring clamp or band 208.

The operation of the embodiment shown'in FIGS. 4 and 5 is quite similar to that of the previous embodiment except that here in the pneumatic operation of closure 190 the cylinder 146 is maintained stationary while the piston 144 moves. The primary gas is applied by hose 120 into boss 118 and to manifold 136. The spoke passageways 132 thus rise to the pressure of the primary source, and the primary gas begins to be directed or injected at high velocity in a downstream direction into housing passageway ll2'via nozzles 138. At the same time, primary gas flows into annular passageway 150 and pressurizes chamber 142. Valve 154 is driven inwardly to where it bottoms within cupshaped member 152 freeing balls 162 which fall inwardly against neck 160. Piston 144 become unlocked. The pressure within chamber 142 creates a force which rapidly drives piston 144 to its full extended position, this axial movement being limited by bumper ring 176 abutting the upper end of cylinder146. Closure 190, by virtue of being connected to piston 144, is now extended to its full open position, and passageway 112 is opened at its inlet end.

A large mass of ambient air is now entrained into passageway 112 by the high-velocity primary gas flow from nozzles 138 into passageway 112. The air mixes with the primary gas and flows out of the diffuser 116 to inflate the inflatable. The surfaces exposed to the flow of gas are designed to provide for a smooth flow in order to offer a minimal resistance to the primary gas and the entrained air so that high mass flow ratios can be obtained and thereby rapid inflation of the inflatable 206.

Returning now briefly to the commencement of the inflation cycle, the gas which flows into chamber 142 also makes its way past the cup-shaped member 152, the one-way seal 178, and the bumper ring 176 into the upstream annular chamber 183 and on into passageway 180 and reservoir 184. However, the pressure build-up in chamber 183 during'the time it takes for piston 144 to unlock does not reach a level sufficient to counter the opening force created within chamber 142. In addition, the cross-sectional area of the piston exposed to pressure in ehamber 142 is larger in area than the cross-section at chamber 183. Therefore, a net forward axial force attains to maintain closure 190 in the full open position while primary gas pressure is applied. As inflation progresses, the primary gas continues to flow past seal 178 and ring 176 into passageway 180 until the pressure build-up in passageway 180 and in reservoir 184 attains the full pressure of the primary source.

After inflation is completed and the primary source terminates, the pressure level within spider 126 and chamber 142 follows that of the source and thus drops to essentially atmospheric pressure. The pressure within reservoir 184 and passageway 180 does not decay because of the action of piston seal- 178. The pressure differential across this seal causes it to expand and seal the flow path between piston 144 and cylinder 146. This reservoir of trapped, high-pressure gas applies a force. against seal 1'78 and thereby against the v space 183. However, the pressure remains at a level suflicient to effect a fast and complete return of piston 144, and thereafter to maintain the-piston in this position against the back pressure acting on the underside of closure 190. As a safety feature to guard against the opening of closure 190, the ball-lock mechanism engages upon the return of piston 144. Valve 154 moves outwardly under the urging of spring 156. Balls 162 are cammed out into holes 164 and groove 166 to lock the piston to cylinder 146.

In the two embodiments described herein, there has been shown, in addition to the other advantages secured, how a novel pneumatic system can effect both a positive opening and closing of an aspirator passageway by utilizing the pressure of the primary gas. The aspirator housing is opened in response to the pressure of the primary gas to permit entrainment of ambient air for inflation of an inflatable structure. When inflation is complete and the primary source terminates, the housing'is closed and sealed by the action of a trapped quantity of primary gas, thus preventing escape of air from the inflatable.

Having described the present invention with respect to two embodiments thereof, modifications and improvements which secure the advantages of the invention will now become obvious to those skilled in the art; and therefore, it is not the intent to limit the invention by the specific disclosures herein but only by the scope of the appended claims.

What is claimed is:

1. An aspirator comprising:

a. a housing having a passageway therethrough;

b. means for receiving a gas under pressure and directing said gas into said housing passageway as an aspirating gas flow;

c. a closure for said housing passageway;

d. means for pneumaticallyoperating said closure,

including:

1. a piston,

2. a cylinder,

3. said piston and cylinder being arranged for relative axial movement,

4. one of said piston and cylinder being operably connected to said closure,

5. a gas reservoir in communication with said receiving means for storing a volume of pressurized gas,

6. said gas reservoir further being in operative association with said piston and cylinder to effect by the pressure in said reservoir a relative axial movement therebetween such that upon decline in pressure of the gas admitted to said aspirator, the pressurized gas stored in the reservoir effects relative movement between said piston and cylinder to close said closure and thereby seal said housing passageway.

2. An aspirator as claimed in claim 1 wherein said piston is stationary and said cylinder is slidable thereon, said. cylinder being operably connected to said closure to; effect movement thereof.

3. An aspirator as claimed in claim 2 further comprising a one-way seal mounted on said piston which permits the flow of to said reservoir in response to a pressure differential ina first direction but prevents the flow of gas from said reservoir in response to a differential in pressure in a reversed direction.

4. An aspirator as claimed in claim 3 wherein a portion of said piston adjacent to said seal has a diameter less than that of said cylinder, said gas reservoir being the annular space defined by such piston portion and the surrounding cylinder.

5. An aspirator as claimed in claim 3 wherein:

a. said receiving means includes a chamber for receiving gas under pressure;

b. said gas reservoir is in communication with said chamber; and

c. said piston and cylinder effect relative axial movement in response to the pressure in said chamber, such that said cylinder moves slidably along said piston to extend said closure to an open position and thereby open said passageway to ambient air.

6. An aspirator as claimed in claim 5 wherein said receiving means further includes a plurality of elongated passageways formed in said closure, each of said elongated passageways having a plurality of aperatures for directing said gas into said housing passageway as an aspirating gas flow.

7. An aspirator as claimed in claim 6 further comprising a plurality of nozzles, each of said nozzles being connected to a different one of said apertures in said elongated passageways.

8. An aspirator as claimed in claim 7 wherein said nozzles terminate at different downstream points in said housing passageway.

9. An aspirator as claimed in claim 8 wherein said nozzles are disposed in radially spaced relation, and the radially outermost nozzles terminate the furthest downstream and the radially innermost nozzles terminate the least downstream.

10. An aspirator as claimed in claim 7 further comprising means for locking said cylinder to said piston when said closure is in the closed position.

11. An aspirator as claimed in claim 10 wherein said locking means includes:

a. a cup-shaped extension on said piston having a hole formed therein;

b. a groove formed in the wall of said cylinder, said groove being in alignment with said hole when said closure is in the closed position;

c. a ball which nests in said hole and groove;

d/a spring-biased member slidably received within said cup-shaped member and having a surface formed thereon which maintains said ball in a nesting relationship within said hole and groove.

12. An aspirator as claimed in claim 1 1 further comprising:

a. a spider positioned in said housing passageway, said spider having an elongated tubular member centrally located thereon for receiving said piston and cylinder,

b. one end of said piston being secured to said tubular member.

13. An aspirator as claimed in claim 1 wherein said cylinder is stationary and said piston is slidable therein, said piston being operably connected to said closure to effect movement thereof.

14. An aspirator as claimed in claim. 13 further comprising a one-way seal mounted on said piston which permits the flow of gas to said reservoir in response to a pressure differential in a first direction but prevents the flow of gas from said reservoir in response to a differential in pressure in a reversed direction.

15. An aspirator as claimed in claim 14 wherein:

a. the upstream portion of said piston has an elongated passageway which opens at its upstream end into'a hollow enlarged portion of said piston;

b. the bottom of said passageway having at least one 5 opening through said piston, said opening being adjacent to said seal; and

c. said hollow enlarged portion and said elongated piston passageway defining said reservoir.

16. An aspirator as claimed in claim 14 wherein:

a. said receiving means includes a chamber for receiving gas under pressure;

b. said gas reservoir is in communication with said chamber; and

c. said piston and cylinder effect relative axial movement in response to pressure in said chamber, such that said piston moves slidably within said cylinder to extend said closure to an open position and thereby open said passageway to ambient air.

17. An aspirator as claimed in claim 16 further comprising:

a. a spider mounted in said housing passageway and including:

1. a hub,

2. a rim,

3. a plurality of radial spokes connecting said hub to said rim, and

4. said rim being supported by said housing thereby to mount said spider in said housing passageway;

b. said receiving means further including:

1. an elongated passageway formed through each of said spokes,

2. an annular manifold formed in said rim, and

3. said elongated spoke passageways terminating radially outwardly at said manifold;

c. each of said elongated spoke passageways having a plurality of apertures for directing said gas into said housing passageway as an aspirating gas flow.

18. An aspirator as claimed in claim 17 further com- 40 prising means for locking said piston to said cylinder when said closure is in the closed position.

19. An aspirator as claimed in claim 18 wherein said locking means includes:

a. a cup-shaped extension on hole'formed therein;

b. a groove formed in the wall of said cylinder, said groove. being in alignment with said hole when said closureis in the closed position;

c. a ball which nests in said hole and groove;

d. a spring-biased member slidably received within said cup-shaped member and having a surface formed thereon which maintains said ball in a nesting relationship within said hole and groove.

20. An aspirator as claimed in claim 18 further comprising: i

a. an elongated tubular member attached to said hub for receiving said piston and cylinder, said tubular member being closed at its downstream end;

b. said chamber being located within the downstream said piston having a end of said tubular member.

21. An aspirator comprising: a. a tubular housing having:

1. an inlet end, 2. an outlet end, and

3. a passageway between said inlet and outlet ends; b. a closure adjacent to the inlet end of said passageway;

c. said closure being extendable from a closed position, in which said passageway is sealed at its inlet end, axially outwardly to an open position in which said passageway is open at its inlet end;

d. inlet means on said closure for communicating with a primary gas supply;

e. a chamber formed within said closure in communication with said inlet means;

f. a plurality of elongated passageways formed in said closure in communication with said chamber;

g. each of said elongated passageways having-a plurality of apertures for directing primary gas into said passageway of said housing as an aspirating gas flow; 1

h. means for pneumatically opening and closing said closure, including:

1. a cylinder connected to said closure and in communication with said chamber,

2. a fixed piston,

3. said cylinder being designed for axial movement relative to said piston in response to the pressure of primary gas within said chamber, thereby to extend said closure to theopen position to permit entrainment of ambient air into said passageway of said housing,

4. a gas reservoir in communication with said chamber for storing a volume of said primary gas, said gas reservoir being operably associated with said piston and cylinder,

5. a one-way seal mounted on said piston permitting primary gas flow to fill said reservoir,

6. said one-way seal trapping the gas in said reservoir upon a decline in primary gas pressure, said trapped gas effecting relative axial movement upon said piston and cylinder to return said cylinder to its initial position and thereby retract said closure to the closed position to seal said housing passageway.

Claims

1. An aspirator comprising: a. a housing having a passageway therethrough; b. means for receiving a gas under pressure and directing said gas into said housing passageway as an aspirating gas flow; c. a closure for said housing passageway; d. means for pneumatically operating said closure, including: 1. a piston, 2. a cylinder, 3. said piston and cylinder being arranged for relative axial movement, 4. one of said piston and cylinder being operably connected to said closure, 5. a gas reservoir in communication with said receiving means for storing a volume of pressurized gas, 6. said gas reservoir further being in operative association with said piston and cylinder to effect by the pressure in said reservoir a relative axial movement therebetween such that upon decline in pressure of the gas admitted to said aspirator, the pressurized gas stored in the reservoir effects relative movement between said piston and cylinder to close said closure and thereby seal said housing passageway.

2. a cylinder,

2. An aspirator as claimed in claim 1 wherein said piston is stationary and said cylinder is slidable thereon, said cylinder being operably connected to said closure to effect movement thereof.

2. a fixed piston,

2. an outlet end, and

2. an annular manifold formed in said rim, and

2. a rim,

3. a plurality of radial spokes connecting said hub to said rim, and

3. said elongated spoke passageways terminating radially outwardly at said manifold; c. eacH of said elongated spoke passageways having a plurality of apertures for directing said gas into said housing passageway as an aspirating gas flow.

3. a passageway between said inlet and outlet ends; b. a closure adjacent to the inlet end of said passageway; c. said closure being extendable from a closed position, in which said passageway is sealed at its inlet end, axially outwardly to an open position in which said passageway is open at its inlet end; d. inlet means on said closure for communicating with a primary gas supply; e. a chamber formed within said closure in communication with said inlet means; f. a plurality of elongated passageways formed in said closure in communication with said chamber; g. each of said elongated passageways having a plurality of apertures for directing primary gas into said passageway of said housing as an aspirating gas flow; h. means for pneumatically opening and closing said closure, including:

3. said cylinder being designed for axial movement relative to said piston in response to the pressure of primary gas within said chamber, thereby to extend said closure to the open position to permit entrainment of ambient air into said passageway of said housing,

3. An aspirator as claimed in claim 2 further comprising a one-way seal mounted on said piston which permits the flow of gas to said reservoir in response to a pressure differential in a first direction but prevents the flow of gas from said reservoir in response to a differential in pressure in a reversed direction.

3. said piston and cylinder being arranged for relative axial movement,

4. one of said piston and cylinder being operably connected to said closure,

4. said rim being supported by said housing thereby to mount said spider in said housing passageway; b. said receiving means further including:

5. An aspirator as claimed in claim 3 wherein: a. said receiving means includes a chamber for receiving gas under pressure; b. said gas reservoir is in communication with said chamber; and c. said piston and cylinder effect relative axial movement in response to the pressure in said chamber, such that said cylinder moves Slidably along said piston to extend said closure to an open position and thereby open said passageway to ambient air.

11. An aspirator as claimed in claim 10 wherein said locking means includes: a. a cup-shaped extension on said piston having a hole formed therein; b. a groove formed in the wall of said cylinder, said groove being in alignment with said hole when said closure is in the closed position; c. a ball which nests in said hole and groove; d. a spring-biased member slidably received within said cup-shaped member and having a surface formed thereon which maintains said ball in a nesting relationship within said hole and groove.

12. An aspirator as claimed in claim 11 further comprising: a. a spider positioned in said housing passageway, said spider having an elongated tubular member centrally located thereon for receiving said piston and cylinder, b. one end of said piston being secured to said tubular member.

14. An aspirator as claimed in claim 13 further comprising a one-way seal mounted on said piston which permits the flow of gas to said reservoir in response to a pressure differential in a first direction but prevents the flow of gas from said reservoir in response to a differential in pressure in a reversed direction.

15. An aspirator as claimed in claim 14 wherein: a. the upstream portion of said piston has an elongated passageway which opens at its upstream end into a hollow enlarged portion of said piston; b. the bottom of said passageway having at least one opening through said piston, said opening being adjacent to said seal; and c. said hollow enlarged portion and said elongated piston passageway defining said reservoir.

16. An aspirator as claimed in claim 14 wherein: a. said receiving means includes a chamber for receiving gas under pressure; b. said gas reservoir is in communication with said chamber; and c. said piston and cylinder effect relative axial movement in response to pressure in said chamber, such that said piston moves slidably within said cylinder to extend said closure to an open position and thereby open said passageway to ambient air.

17. An aspirator as claimed in claim 16 further comprising: a. a spider mounted in said housing passageway and including:

18. An aspirator as claimed in claim 17 further comprising means for locking said piston to said cylinder when said closure is in the closed position.

19. An aspirator as claimed in claim 18 wherein said locking means includes: a. a cup-shaped extension on said piston having a hole formed therein; b. a groove formed in the wall of said cylinder, said groove being in alignment with said hole when said closure is in the closed position; c. a ball which nests in said hole and groove; d. a spring-biased member slidably received within said cup-shaped member and having a surface formed thereon which maintains said ball in a nesting relationship within said hole and groove.

20. An aspirator as claimed in claim 18 further comprising: a. an elongated tubular member attached to said hub for receiving said piston and cylinder, said tubular member being closed at its downstream end; b. said chamber being located within the downstream end of said tubular member.

21. An aspirator comprising: a. a tubular housing having: