US2340166A - Booster pump entry vane construction - Google Patents

Description

. Jan. 25, 1944. J. w. YOUNG ET L 2,340,166

BOOSTER PUMP ENTRY V ANE CONSTRUCTION Filed Jan. 21, 1942 1/06 A/ Xw/ve a 2 'f AUL J. ZANJ/n e Patented Jan. 25, 1944 noos'rna PUMP ENTRY VANE oonsrauorron John W. Young and Paul J. Lansing, Los Angeles,

Calif., assignors to Thompson Products, Incorporated, Cleveland,- Ohio, a corporation of Ohio Application January 21, 1942, Serial No. 427,556

' 8 Claims. (or. 103-113 The present invention relates to a booster pump construction adapted for use in a fuel system for pressuring liquid fuel therein while at the same time separating gases and vapors from the fuel as it is being pressured.

More specifically, this invention relates to an entry baiiie at the throat inlet of a centrifugal type of booster pump for breaking up a vortex of whirling liquid fuel caused by rotation of an agitating impeller as the fuel enters the pump inlet throat whereby a more efficient separation of gases and vapors from the fuel is effected.

While the invention will be specifically described in connection with aircraft fuel systems, it should be understood that the invention is not limited to such use but is broadly applicable to any system wherein it is desired to deliver only fully liquid material from a source containing the liquid admixed with gases and vapors or having highly volatile ingredients therein. The invention is particularly applicable for use in fuel systems for the prevention of vapor-lock therein.

It has been found possible to actually beat out air, gases and vapors from a pond of fuel by agi tating the fuel below the hydraulic gradient of the pond. By using a centrifugal-booster pump having a flared inlet throat, the fuel is subjected to a whirlpool action by the impeller thereof as the fuel flows from the pond into the pump inlet, whereby the lighter gaseousbubbles are thrown upwardly and outwardly, where they eventually rise through the pond, while fully "liquid fuel is delivered under pressure to a. delivery line of the fuel system.

In other words, gases and vapors dispersed throughout the liquid being subjected to agitation are beaten out of the liquid by forming the same into bubbles which rise through the liquid and eventually burst into the atmosphere at the top surface thereof. This beating of the liquid not only creates bubbles from the occluded gases and vapors therein but also induces the liberation of such gases and vapors still held in dissolved form in the liquid. The volatiles dissolved in the liquid, which are about to separate from the liquid as gases or vapors, arecaused to separate in the form of newly created bubbles produced by the beating action. As a result, the liquid is not only freed of the occluded gases and vapors but is stabilized against the generation of additional occluded gases or. vapors. 2

In the operation of aircraft with gasoline or other volatile-liquid as a fuel, it is well known that, as the atmospheric pressure drops with increase in altitude, a point is finally reached Where the air and fixed gases in solution start to evolve, and the lighter constituents in the fuel to vaporize, until the engine fuel pump is no longer capable of delivering fuel in a fully liquid form to the engine carburetor. This condition frequently gives rise to what is known in the art as vaporlock. The agitation of the fuel by the usual engine pump serves to aggravate the difllculties that may be experienced, by accelerating the separation of air or other fixed gases or vapors from the liquid fuel. In accordance with the operation of a booster pump construction of the type illustrated and to be described herein, these gases and vapors are liberated from the fuel before they reach the engine fuel pump and the gas and vapor-freed fuel is maintained under pressure as it is fed to the engine fuel pump, so that the vapor-lock condition cannot occur. The. engine fuel pump thus not only receives a more stable liquid fuel, but receives this fuel under pressure.

The centrifugal type of booster pump usually employed for such gas and vapor separation includes an impeller having curved vanes partially overlapped byan inlet throat defining member.

For the proper operation of such a booster pump construction, it is necessary that the pump be positioned below the hydraulic gradient of the pond containing the liquid admixed with the gases and vapors. The usual practice is to connect such a booster pump construction directly to a fuel tank, eitherat the bottom or at one of the sides thereof. adjacent the bottom so that the pump inlet throat opens directly into the liquid pond. In aircraft, this relative positioning of the elements of a fuel system is possible only when sufilcient room is available below or at the side of a fuel tank mounted either in the wings or the fuselage.

In some aircraft constructions, however, there is no space immediately adjacent the fuel supply tank whereby a booster pump may be mounted on a wall thereof. In such cases, it is necessary to connect the fuel tank and booster pump by a fuel delivery line whose inside diameterv should be at least as large as the largest diameter of the pump inlet throat. In those installations where the pump cannot be directly attached to the fuel tank, it has been found most expedient to connect a fuel line to the side of the fuel tank and often this requires that the fuel line be shaped as an enlarged elbow in order to maintain the booster pump below the hydraulic gradient of the fuel tank. The shape of the fuel line along its longitudinal axis and the length thereof will depend entirely upon the distance from th fuel tank and the position of available space for mounting the booster pump. In the present invention, the fuel line connecting the fuel tank and booster pump extends outwardly from a side wall thereof adjacent its bottom wall and then downwardly into (connection with the inlet of the pump.

In such an installation, the liquid fuel in the fuel line is subjected to agitation by the impeller of the fuel pump which sets up a vortex or whirling motion in the mass of 'fluid therein. As gases and vapors are liberated from the fuel at the inlet throat of the pump, they may be impeller and which throat construction directs flow of liquid to the impeller axially thereof in a path separate from a counter-path of released gas and vapor bubbles.

Another and still further object of this invention is the provision of an inlet throat construction, having a baflle therein, for a centrifugal type of pump which throat and baflle coacts with an agitating impeller to effect a separation of gases and vapors from a liquid fuel and to simultaneously pressure the gas and vapor-freed fuel without any pulsations in the discharge from the trapped by the downwardly flowing fuel and tend and the dispersement thereof permits the liquid fuel to again flow into the inlet pump throat into contact with the impeller vanes whereby the impeller speed is immediately reduced in overcoming the inertia of theheavier liquid. Thus slugs of llquidvand pockets of gas or vapor are alternately acted on by the impeller and pulsations occur in the speed of the pump with resulting pulsations of the liquid fuel into the delivery line of the fuel system. This alternate pumping of gases and vapors and liquid fuel causes an early failure in operation of the vehicle engine which is extremely dangerous when the vehicle is an aircraft as it usually results in complete operational failure of the motive power or may be undesirable by restricting the altitude at which the aircraft can be flown.

The present invention seeks to overcome this hazard by the insertion of a baiile at the inlet of the pump for the purpose of breaking up the vortex or whirlpool flow of the fluid as it enters the pump thereby directing the flow of fully liquid fuel in an axial direction into the pump while simultaneously directing the separated bubbles of gas and vapor outwardly and upwardly around the inner periphery of the fuel line. This assures a constant and even separation of gases and vapors from the liquid fuel and the pumping of a constant volume of fully liquid fuel into the delivery line of the fuel system.

It is then an object of the invention to break up the whirlpool flow of liquid to a centrifugal .pump.

An important object of this invention is to maintain a continuous separation of gases and vapors from a liquid fuel and the pumping of a continuous stream of fully liquid fuel by a booster pump receiving fuel flowing in a path whose direction of flow is changed between a source of fuel and the booster pump;

. Another object of this invention is the provision of a booster pump having an impeller for agitating liquid fuel flowing thereto with a baflle in the inlet throat thereof for directing the flow A 'still further object of this invention is the provision of an inlet throat construction for a centrifugal type of pump having an agitating A still further object of this invention is the provision of a baille that seats on the inlet throat of a centrifugal pump to extend thereabove into a path of liquid fuel and to coact with the throat for directing the fuel axially into the throat whereby a constant separation of gases and vapors from the liquid fuel is effected by an impeller which simultaneously pumps a constant volume of gas and vapor-freed'fuel to the dis- I charge outlet of the pump.

The novel features believed to be characteristic of the present invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and manner of construction, together withfurther objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in which:

Figure 1 is a broken and fragmental vertical cross-sectional view, with parts in elevation, of

a booster pump, a fuel tank and a flow connecseen in a plane taken along the line 11-11 thereof;

Figure 3 is a transverse cross-sectional view, with parts in elevation, as seen when taken in the plane indicated by the line III-III of Figure 2;

Figure 4 is a view similar to Figure 2 illustrating a modified form of construction of the booster pump and battle arrangement shown in Figure 2; and,

Figure 5 is a view similar to Figure 3 illustrating themodifled form of construction shown in Figure 4 as seen when taken in the plane substantially along the line V-V of Figure 4.

In Figure 1, the reference numeral Ill designates a gasoline tank having a bent I l and which holds a pond P of gasoline or other volatile engine fuel. A booster pump assembly I2 is connected in flow communication with the tank ill by means of a pipe member l3. This pipe memher or flow communication I3 is formed as an elbow with one end being connected to a side wall I! of the tank adjacent the bottom wall thereof and opening into the pond? of fuel. The other booster pump assembly I! in a manner to be more fully described hereinafter.

The elbow type flow connection between th tank I! and booster pump assembly I! gillustrated in Figure 1 is made necessary in the present instance by lack of mounting space immediately adjacent the tank for the booster pump.

In the usual assembly of elements, a booster pump, such as I2, is mounted directly on either the bottom wall or a side wall of the tank around an aperture therein whereby the pump inlet opens directly into the pond P of fuel. In such installations in which all of the available space is filled by the fuel tank l0, then a connection such as illustrated in Figure 1 may be provided. In this case, the flow communicating member between the fuel tank and booster pump extends outwardly from the tank and then downwardly into connection with the booster pump to position the latter below the hydraulic gradient of the pond P. Liquid fuel flowing from the fuel tank Ill to the inlet of the booster pump assembly l2 thereby changes direction by first flowing outwardly and then downwardly.

The lower end of the pipe elbow member 88 has. a radially extending flange l5 thereon to which the booster pump assembly l2is connected by means of studs IB. v

The pump assembly I2 is composed of 9. casing l1 shaped to define a pump volute chamber l8 and an out-turned annular flange is receiving the studs l5 therethrough, a throat ring 26, and an impelle 2i driven by a shaft 22froma source of motive power such as an electric motor (not shown). The impeller ,28 is composed ofa hub portion 23 keyed or otherwise secured on the shaft 22 and maintained thereon by a nut 2d. The impeller also has a disk portion 25 spanning an inlet opening 25 defined by the throat ring 26. The disk 25 communicates around the periphery thereof with the volute chamber 58 and has upstanding curved pumping vanes 2'8 underlying th throat ring, as best shown in Figures 1, 2 and 3.- It is preferred that the pumping vanes 27 have tapered inner end portions 23 disposed within the inlet opening 25, which, as will be explained hereinafter, serve as agitators or beaters for separating bubbles of gas and vapor flowing through the elbow member ill to the inlet throat ring 20.

The pump casing ll, between the volute chainber i8 and the out-turned flange i9, is so shaped as to provide an annular shoulder 29 and a substantially horizontal seat 3%. The throat rim it has its outer periphery shaped to complementally engage within and seat on the surfaces 2% and of pump casing. Connection therebetween is effected by flathead screws 3%.

The outer periphery of the impeller, defined by the ends of the vanes 21, is positioned between the throat ring 2E and an annular flange portion 32 (see Figure 2) on the inside of the pump casing 51 in order that the fuel be delivered under pressure through the volute chamber is into an outlet 33 which is connected through a pipe line or tube 35 to the inlet of anengine fuel pump (not shown). A pump casing portion 35 houses the driving shaft 22 which is connected to a source of motive power for driving the impeller, such as an electric motor (not shown).

If necessary or desirable, a gasket 3E may be interposed between the flange portion it of the pump casing and the radially extending flange lb of the lower end of the elbow member H to seal the connection therebetween.

The throat ring 20 preferably flares outwardly from the inlet opening 26 in'an axial direction-to provide the angular extending annular surface 31, The outward flaring surface of the throat ring provides an enlarged mouth in direct communication with liquid flowing from the pond P through the elbow member l3 and the tapered surface 31 terminates in laterally spaced relation from the inner periphery of the elbow member l3; It is to beunderstood, however, that although it is preferred to form the inner periphery of the throat ring as described above, the broad aspects of this invention include a throat ring whose inner periphery may be formed of any flat or curved surfaces at different angles or described by various radii.

When the booster pump I2 is at rest, liquid fuel from the pond P can freely flow through the elbow member l3 and the pump inlet 26 along the open'ended channels defined by the impeller disk 25 and the curved vanes 21 into the volute chamber l8 where it can bewithdrawn through the outlet 33 and pipe line 36 into the fuel line for discharging the liquid fuel to the inlet side ofa fuel pump. Thus, even though the booster pump 52 is at rest, the usual fuel pump in a fuel system can always receive fuel on. its suction side from the pond P.

In the event that the fuel pump becomes in operative, the booster pump l2 can pressure the fuel to the inlet of the pump where itcan be forced therethrough or by-passed therearound to feed fuel to an engin carburetor connected to the fuel line (not shown).

In accordance with the principles involved with the pump illustrated and described herein,

the booster pump' 12 is operated so as to beat out gases and vapors from the liquid fuel being sent to the fuel pump. The vane portions 28 of the impeller 2| agitate the fuel in-the inlet 26 of the pump and actually beat out bubbles G of gas and vapor from the liquid fuel. The impeller'vanes create a vortex or whirling mass of fluid in the elbow member-l3, the particles of which rotate in the same direction as the impeller and move in a corkscrew fashion toward it.

The bubbles G are thrown by the vanes outwardly along the flared surface 3! of thethroat ring and, being lighter than the liquid fuel, rise within the elbow member i3 adjacent the inner periphery thereof.

The light bubbles of gas and vapor, rising upwardly in the vertical leg of the elbow member l3, tend to flow into the path of liquid flowing through the horizontal leg of thernember l3 and are thereby drawn downwardly towards the impeller with the liquid fuel. A layer or mass of bubbles then forms across the inlet throat cutting off the flow of liquid fuel into the throat. The vane blades then'tend to race at full speed by reason of the low inertia of the-gas and vapor bubbles. Increased agitation of the mass of bubbles or pockets of vapor tends to force bubbles outwardly along the tapered surface of the throat ring thereby breaking up the pocket. as the mass of bubbles is dispersed, a slug of liquid fuel flows into the inlet throat and the speed of the impeller is immediately reduced by the inertia of the liquid fuel against rotation.

This alternate formation of vapor pockets and feeding of slugs of liquid. together with the alternate variations in impeller speeds, causes pulsations in the delivery of the fuel to the fuel line.

The efiect of this pulsating delivery is to efiect early operational failure of the motiv power which depends upon the constant delivery of fully liquid fuel thereto. In order to overcome this pulsating delivery of fuel, abaflle member 38 is inserted in the inlet 26 of the booster pump in such a manner as to break the vortex of the whirling mass of liquid fuel in the elbow member l3 adjacent the pump inlet throat.

The baliie member 38 comprises a plate member having-tapered corners for seating on the tapered surface 31 of the throat ring 20. A recess 3! is provided along the bottom edge of the baflie As soon in order that there be sufficient clearance above the impeller nut 24 and the agitating portions 28 on the vanes. The length of the baflie 38 is substantially the same as the diametrical distance across the throat ring at its widest tapered portion. This provides spaces 40 and M between the ends of the baffle and the adjacent peripheral portion of the elbow member l3. The height of the bailie is such as to extend above the throat ring 20 and into the vertical leg of the elbow member l3.

The tapered corners of the baffle seated on the tapered surface, 21 of the throat ring are connected to the throat ring by means of a bond such as brazing, welding or the like.' It is to be understood, however, that the throat ring 20 and baiile 38 may be formed or cast as a single unitary member. Likewise, radial slots may be provided along the tapered surface 31 of the throat ring 20 within which the tapered corners of the baiile may be pressed or otherwise secured in place in a manner similar to that to be described more fully hereinafter.

As shown by the arrows in Figure 3, the whirl ing mass of liquid fuel in the vertical leg of the elbow member I3 strikes the sides of the baffle not restrict the separation of gas and vapor,

bubbles from the liquid fuel by agitation of the impeller vanes 21 and the bubbles are thrown outwardly along the tapered surface 31 of the throat ring where they rise upwardlyaround the inner periphery of the elbow member l3. The bubbles G continue to rise through the elbow member into the pond P and upwardly in the latter to the top thereof where they burst at the surface and liberate the entrapped gases and vapors to theatmosphere through the vent ll. Even though some of the bubbles G are again drawn downwardly towards the axis of rotation of the impeller, they are immediately thrown outwardly by the impeller vanes and the axially directed fully liquid fuel only flows into the open ended channels defined by the impeller, the pump casing and the throat ring for delivery through the volutechamber into the delivery line of the fuel system. By breaking the vortex or the whirling mass of liquid fuel adjacent the rotational axis of the impeller, the opportunity for the bubbles G forming in a mass or layer across the inlet throatis eliminated; Consequently, the separation of gas and vapor bubbles and the simultaneous pressuring of the liquid fuel continues at a. constant rate and thereby eliminates pulsations in the delivery of the fuel.

It will be observed from the foregoing that a counter-current circulation of, fuel and bubbles is thus created in the elbow member l3, with the bubbles rising through the fuel along the inner periphery of the elbow member and with the fully liquid fuel being fed axially towards the impeller through the inlet throat. The fully liquid fuel is then subjected to centrifugal action between the vanes 21 on the impeller and the throat member to effect a constant delivery of pressured fuel to the delivery line of the fuel system.

The spaces 48 and ll between the bafile 38 and the inner periphery of the elbow member l8 permit the bubbles to' flow upwardly along the tapered surface 31 of the throat ring and to then rise along the inner periphery of the elbow member without any interference by the baflle. Thus,

the fuel induces bubble formation and stabilizes the liquid through separation therefrom of volatiles about to become vapors or gases and the extending baflie breaks up the whirling motion of the mass of fluid whereby fully liquid fuel only flows into the volute chamber [8.

While the fuel system as described is used in aircraft which fly to high'altitudes, the booster pump I2 can be started before the fuel starts breaking up in the pond or the flow communication elbow so that the fuel will be maintained stabilized at practically any atmospheric pressures encountered. As a result, the aircraft can be flown to much higher altitudes, and even though the fuel breaks up at these high altitudes, the booster pump will insure'delivery of only fully liquid fuel from the pond to the fuel delivery line.

A modified form of construction is illustrated in Figures 4 and 5 of the drawing. Like numerals refer to like parts throughout all of the figures of the drawing.

The booster pump construction illustrated in Figures 4 and'5 is exactly the same as thatv shown in the previous figures of the drawing. The only change is in the construction of the baflle means.

In the modified form of baffle construction, a cross-shaped baiile member 50 is formed by right angularly extending plate members whose lower outer corners are beveled at the same angle as the tapered surface 31 on the throat ring 20. In this form of construction, it is preferred that diametrically opposed slots 5| be provided along the tapered surface 31 of the throat ring for receiving therein the beveled comers of the baffle 50. The bafile member is press-fitted within these slots 5| for ease in removal or may be positively connected by means of brazing, welding or the like. Likewise, it is within the purview of this invention to form .the throat ring 20 and the baffle 50 as an integral member.

.The lower edge of the baffle member 50 is spaced upwardly from the vanes 21 and the impeller nut to eliminate any interference in-the separation of gas and vapor bubbles within the inlet throat 26.

The length of the plates forming the baffle member 50 is such that they terminate in spaced relation from the inner periphery of the elbow member l3. to provide the spaces 40 and 4| for the same purpose as hereinbefore described. Also, the baffle member 50 extends above the throat ring 20 into the vertical leg of the elbow member l3 in order to break the vortex or the whirling mass of liquid fuel adjacentthe inlet The baffle member 68 c'oacts with the booster construction I! in exactly the same manner as the baille 38 which was described in detail above. The baffle member 38 diametrically extends across the inlet opening 26 0120. Provide adjacent inlet openings for directing the liquid fuel axially to the impeller. The provision of the baffle member 50 further divides the inlet Opening into four axial channels through which the liquid fuel is directed toward the impeller.

From the foregoing description, it will be ap parent that the booster pump described has three functions; the first, to separate out bubbles of gas or vapor which form at the inlet, due to the agitation of the liquid, and elsewhere in the.pond or flow connection between the pond and booster pump; the second, to break the vortex or whirling mass of liquid fuel to direct the liquid axially toward the impeller; and the third, to pressure the fully liquid fuel througha fuel line.

The booster pump construction of this invention havingv a baiile as described eifects a full separation of gases and vapors from the liquid fuel and maintains a constant flow of fuel imder presure to a fuel line thereby eliminating any pulsations in the fuel delivery.

While particular embodiments of this invention have been illustrated, it will, of course, be understood that the invention should not be limited thereto 'since many other modifications may be made, and, therefore, it is contemplated by the appended claims to cover all such modifications as fall within the true spirit and scope of the present invention.

We claimas our invention:

1. In a booster pump construction having a tapered inlet throat, a source of liquid fuel having gas and vapor dispersed therethro gh from which said liquid is supplied to said inlet throat. and an impeller underlying said throat for agitating the liquid in a whirling motion as it flows to said throat, the improvements comprising flow communicatingjmeans connecting said source of liquid and said throat, and a baille member extending across and axially outward from the mouth of said throat into said communicating means in spaced relation thereto for breaking the whirling motion of said agitated liquid whereby the liquid flows axially to the impeller inside of a path of gas and vapor bubbles separated from the fuel by agitation by said impeller. V

2. In a booster pump construction having a tapered inlet throat, a source of liquid fuel having gas and vapor dispersed therethrough from which said liquid is supplied .to said inlet throat, and an impeller underlying said throat for agitating the liquid in a whirling motion as it flows to said throat, the improvements comprising a hollow elbow member interposed between said source of liquid and said throat for positioning the throat below the hydraulic gradient of said source, and a banie member extending across the mouth of said throat into said elbow member and terminating in spaced relation from the inner periphery of said elbow member, said baifle member extending axially outward from the throat into the whirling path of movement of the liquid in said elbow member whereby the liquid is di-- rected axially to the impeller inside of apath of gas and vapor bubbles separated from the fuel by agitation of said impeller and flowing outwardly and upwardly along said throat between said baffle and the inner periphery of the elbow member baiile means within and spaced from said commimication member for directing the flow of fuel from said source to said impeller in a path countertoandwithinapa'thofgasandvapor bubbles separated from the fuel by agitation by said impeller.

4.Inaboosterpumpconstructionhavinga taperedthroat,anasitatingimpelleronone side of said throat,andasource of liquid fuel havinggasandyapordispersedtheretbrough,

the improvements which comprise a flow con necting member'between said source andsaid tapered throat on the other side thereof for.

changing the direction of flow of the'liquid therebetween, said impeller agitating said liquid fuel in a whirling motion as it flows through necting member for breaking the whirling motionoftheliquidadjacentthethroat attherotational axis thereof whereby gas and vaporfreed fuel flows through the throat;

5. In a centrifugal pump having an inlet and an agitating impeller, the improvements which comprise a removable throat ring in said inlet overlappin said impeller in closely spaced relation, said throat ring having a tapered mouth I on the side thereof opposite the side adjacent said impeller, and a bame member extending diametrically across said mouth with one edge overlying the portion of said impeller not overlapped by said throat ring and in spaced relation therefrom with its opposite edge being spaced outwardly from said mouth.

8. In a pump construction having an inlet throat, an impeller having pumping vanes underlapping said throat to centrlfugally whirl. and pump fluids received from the throat. and uncovered agitating vanes on said impeller exposed to the throat opening for acting on fluids flowing to the pumping vanes and effective for ejecting bubbles of gas and vapor from the fluids before the fluids reach the pumping vanes, the improvement of a baiiie extending completely across the throat opening and having side faces effective for breaking up the whirling of fluid flowing to the pumping vanes while directing the fluids substantially axially of the throat open- I. In a fuel system having a tank for a'pond of fuel, a pump having an inlet throat below the top of the tank for receiving fuel by gravity flow from the tank, a fuel conduit connecting the inletthroat and the tank, a centrifugal impeller in said pump adjacent said inlet throat for can trifugally whirling and pumping fuel received .from thethroat, and abaiiie extending completely across the throat projecting into the conduit in spaced relation therefrom eifective for breaking up whirling of fuel in the conduit to direct the fuel axially of the throat opening and toward the impeller.

8. In a fuel system, means for containing fuel, a pump having an inlet throat receiving fuel by gravity flow from said means, a centrifugal impeller in said pump adjacent said inlet throat,

agitating means on said impeller exposed to the throat opening and effective for circulating bubbles of gas and vapor in said means away from the pump, a bailie extending completely across the throat opening and projecting into said means in spaced relation from the means for impeding the whirling of fuel flowing to the pump while permitting free flow of elected bubbles of gas and vapor in the means.

JOHN w. YOUNG. PAUL J. panama.

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