US2316007A - Booster pump throat - Google Patents

Description

Paa'med Apr. 6, 1943 UNITED I STATES PATENT "OFFICE aoos'ran rum 'rnaon'r William J. Lockett, Los Angeles', can, assignor to Thompson Products, Incorporated, Cieve- 1 land, Ohio, a corporationof Ohio Application January '14, 1942, Serial- No." 426,691

9 Claims. (Ci.103--11 1) This invention relatesto a booster pump construction adapted for use in a fuel system to pressure liquid fuel while separating gases and vapors from the fuel as it is beingpressured.

More specifically, this invention relates to an inlet throat construction for a centrifugal type of booster pump which coacts with the pumpimpeller to efliciently effect a separation of .gases and vapors from liquid fuel flowing theretlirough without causing any dropin the simultaneous pressuring of the liquid fuel in the fuel system.

While the'invention will be specifically de'-' pump thusnot only receives a morestable liquidscribed in connection with aircraft fuel systems,

itshould be understoodthat the invention is notlimited to-suchusebut is-broadly applicable to anysystem wherein it is desiredto deliver only fullyliquid materialfrom 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 hasbeen found possible to actually beat out air, other gases, and vapors from a pondof fuel by agitating the fuel below the hydraulic gradient of the pond. By using a centrifugal booster pump havinga'ilarecl inlet throat, the fuel is subjected-t0. a whirlpool action by the impeller thereof as the fuel leaves the pond and flows into I the pump inlet, whereby the lighter gaseous bubbles are thrown upwardly and outwardly into the pond while fully liquid fuel is delivered under pressure to the deliveryline of the fuel systeml In other 'words, gases and vapors dispersed throughout liquid in a pond when the liquid is subjected to agitation are beaten out ofthe liquid by forming the same into;bubbles which-rise through the pond and burst into the atmosphere at the top of the pond. This beating of the liquid notonly'creates bubbles from-the occluded gases and vapors in the liquid 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'gas'e'sor vapors are caused to separate in the form of newly created-bubbles produced by the beating action. As a result, the

liquid is not only freed from occluded gases and vapors but is stabilized against the generation of additional occluded gases or vapors.

In the operation ofaircraft with gasoline or other volatile liquid as a fuel, it is'well known that, as the atmospheric pressure drops with in crease inaltitude, a point is finally reached where the'air and fixed gases .in solution start to evolve, and the lighter constituents in the fuels are varise to what is known in the art as fuel system having an inlet throat which effects a greater liberation of gases and vapors from .porized, until the engine fuel pump is no longer 1 capable of delivering fuel in a fully liquid form to'theengine carburetor.

duently'gives v vapor-lock. The agitation ofithe fuel by the This condition freengine pump serves'to aggravate the difllculties that may be experienced, by ,accelerating the e separation of air or air-fixed gases or vapors from the liquid fuel. In accordance with the present invention, howeven. thesegases and vapors are liberated from the fuel before they reach the engine fuel pump, and the gas and vaporfreed fuel is maintained'under pressure as it is fed to the engine fuel pump, so that the vaporlock conditioncan'not occur. The engine fuel fuel, but receives this fuel under pressure.

' The centrifugal type of booster usually 'emplayed for such gas and vapor separation includes an impeller'whosevanes are overlapped by an inlet throat with the amount of overlap and the speed of the impeller determining the ever,"when the inletthroat opening is enlarged, the vanes on the pump impellervmust be lengthened to maintain the pumping capacity and the "proper pressuring of the fuel delivered to'the fuel line by retaining. substantially the same overlapping of the vanes by the throat.. This enlargement of the parts requires additional power for-maintaining the agitating speed of the im- 4 peller and consequently increases the expense of operationvand the ultimatecost of manufacturing the pump device.- 1

The present invention seeks to eflicientiy increase the gas and vapor separation capacity of booster pumps while at the same time maintain ing the desired pumping capacity for the pump without any enlargement of the pump parts and without increasing the pump speed. This is effected not only by opening up the inlet to the pump but by'also shaping theinlet throat in a particular manner.

It is then an important object of the invention to increase the bubble separation and liberation efficiency of booster pumps by opening up the inlet throats of such pumps.

Another object of this invention is to provide a highly eflicient pump construction for a fuel system wherein gases or vapors are more fully liberated from a'liq'uid fuel flowing into the pump. 1 Another object of this invention is the provision of a centrifugal type of fuel pump for a liquid fuelfiowing to the pump without unduly sacrificing the pumping capacity of the pump.

A further object of this invention is the provision of an inlet threat for a centrifugaltype of fuel pump which is so shaped as to coact with the impeller of the pump to effect a highly effi- It has been found that by enlarging theshown).

tic of the present invention are set forth with.

particularity in the appended claims. The in-' vention itself, however, both as to its organization and manner of construction, together with further objects and advantages thereof, may best be understood by reference to the following detally engage within and seat on the surfaces 21 and 28 of the pump casing. Connection therebetween is effected by flat-head screws 29. The screws 29 are inserted through openings 29a each having a tapered end portion 29b for seating the headed ends of the screws. The threaded portions of the screws are threaded into openings provided in the pump casing as shown in scription taken in connection with the accompanying drawing, in which:

Figure 1 is a fragmentary vertical cross-sectional view, with parts in elevation, of a portion of a fuel system illustrating a booster pump having an inlet throat constructed in accordance with the principles of the present invention;

Figure 2 is a, plan view of the booster pump ,throat and the underlying impeller construction of this invention as seen when looking in the direction of the arrows taken substantially in the plane indicated by the line II-IIof Figure 1;

.Figure 3 is a bottom view of the inlet throat shown in Figure 2; and,

Figure 4 is an enlarged fragmental cross-sectional View showing the curvature of the inlet throat opening and its overlapping relation with respect to the pump impeller as seen. when taken substantially in the plane indicated by the line IV-IV of Figure 2.

In Figure 1, the reference numeral i designates the usual vented (not shown) gasoline tank for holding a pond P of gasoline or other volatile engine fuel. A booster pump assembly II is bolted to the bottom of the tank l0 around an aperture in said bottom by means of studs l2 threaded into an annular abutment ring l3 seated in the tank on the bottom wall thereof. If desired, a gasket I 4 may be interposed between the booster pump and the bottom of the fuel tank for tightly sealing the engagement therebetween.

The pump assembly II is composed of a casing 5 shaped to define a pump volute chamber l6 and an outturned annular flange l'l receiving the studs l2 therethrough,a throat ring 18, and an impeller l9 driven by a. shaft from a source of motive power such as an electric motor (not The impeller I9 is composed of a hub portion 2| keyed= or otherwise secured on the shaft 20 and maintained thereon by a nut 22. The impeller also has a disk portion 23 spanning the inlet opening 24 defined by the throat ring l8. The disk 23 communicates around the periphery thereof with the volute chamber I6 and has upstanding curved pumping vanes 25 underlying the throat ring, as'best shown in Figures 1 and 2. The pumping vanes 25 hav tapered inner end portions 26 disposed within the-inlet opening 24, which, as will be explained .hereinafter, serve as agitators or beaters for separating bubbles of gas and vapor from the fuel in .the pond P.

The pump casing l5 between the volute chamber I 6 and the outturned flange I1 is so shaped as to-provide an annular shoulder 21 and a substantially horizontal seat 28. The throat ring l8 has its outer periphery shaped to complemen- Figure 1..

The outer periphery of the impeller, defined by the ends of the vanes 25, is positioned between the throat ring l8 and an annular flange portion 30 on the inside of the pump casing 15 in order that the fuel be delivered under pressure through the volute chamber l6 into an outlet 3L which is connected through a pipe line or tube 32 to the inlet of an engine fuel pump (not shown). A pump casing portion 33 houses the, driving shaft 20, which is connected to a source of motive power for driving th impeller, such as an electric motor (not shown).

The throat ring l8 flares outwardly from the inlet opening 24 in axial directions toward the top surface 34 and bottom surface 35 thereof, as best shown in Figure 4. The'outward flare of the throat ring towards the top surface 34 provides an enlarged mouth 36 in direct communication with the bottom of the pond P. The bottom portion of the inlet throat is curved to provide a surface 31 lying directly above the fiat outer portion of the curved vanes 25 in such'a manner that th inlet throat overlaps approximately one-third of the length of each vane. It is to be noted in Figure 4 that the curved surface 36 is described by a radius A of much greater length than the small radius B which describes the curved surface 31. These radii are struck from centers spaced from each other but lying on a line C in closely spaced relation from the bottom surface 35 of the throatring IS.

The center of the radius A, describing the surface 36, is so spaced from the top surface 34 of the throat ring that the surfaces are tangentially connected. Likewise, the center of the radius B, describing the surface 31, is so spaced from the bottom surface-'35 of the throat ring that the surfaces are tangentially connected. Furthermore, the centers of radii A and B are so spaced on the line C that the curved surfaces 36 and 31, formed as circle arcs, tagentially connect with each other.

It is to be understood, 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 arcs described .by various radii.

When the booster pump II is at rest, liquid fuel from the pond P can freely flow through the pump inlet 24 along the open ended channels defined by the impeller disk 23 and the curved vanes 25 .into the volute chamber 16 where it can be withdrawn through the outlet 3! and pipe line 32 into the fuel line for discharging the liquid fuel to the inlet side of a fuel pump.

.Thus, even though the boosterpump II is at rest,.the usual fuel always receive fuel pump in a fuel system can on its suction side from the pond P.v

In the event that the fuel pump becomes inoperative, the booster pump II can pressure the fuel to the inletof the pump where it can be forced therethrough or by-passed therearound to feed fuel to an engine carburetor connected to solid or fully liquid .material to the impeller. counter current circulation of fuel and bubbles is thus created in the tank, with the bubbles risimpeller 19 agitate the'fuel in the inlet 2! of the pump and actually beat out .bubbles G of gas and vapor from the liquid fuel. The bubbles G are exposed.

are thrown by the vanes outwardly along the flared-mouth 36 of the throat ring and, being lighter than the liquid fuel, rise'through the pond P to the top thereof where .they burst at the surface and liberate the entrapped gases and vapors to the atmosphere through the vent proj vided in the tank [0. As shown in Figure 1, the bubble path widens out and the bubbles become larger as they approach the surface of the pond P.

The impeller vanes create a funnel-shaped whirlpool in the pond P, the particles of which rotate in the same direction as the impeller and move in a corkscrew fashion toward it. This whirlpool extends well upward into the tank and is present assoon as the booster pump commences to operate. As a result, the fuel freed from air and gases circulates, as indicated by the arrows, down through the whirlpool as a substantially A ing throughthe fuel outwardly from. the whirlpool and with the fully liquid fuel being fed down, through the funnel-shaped whirlpool to the impeller. Y i

The fully liquid fuel is then subjected to centrifugal action between the vanes on the impeller and the throat member, where the last remaining bubbles are forced from the fuel outcurved surface 3I,longer lengths of the blades the suction behind the revolving blades to more effectively generatebubbles of gases or vapors for liberation from the liquid fuel. Furthermore, any bubbles so generated tend to follow the curved surface 31 by rising to a position in which the curved surfaces of the throat ring are tangentially connected where they are then thrown outwardlyby the agitation of the vanes to follow along the curved'surface 36 whence they con-' tinue to riseoutwardly and upwardly'away from the downwardly flowing fuel feed to the pump.

Consequently, the inner. peripheral shape of the throat ring [8 of thepresent invention as sures a more eificient operation of the centrifugal impeller for liberating gases and vapors from a liquid fuel. Fully liquid fuel is thereby pressured into the volute chamber l6 and is maintained under pressure through the outlet 3| and the pipe line 32 to be supplied to a fuel line.

The agitating vaneportions 26 not only beat, the occluded gases and vapors in the fuel into bubble form but also generate additional bubbles from dissolved gases or vapors about to beliberated from the liquid. Furthermore, the outer from of volatiles about to become vapors or gases,

wardly along the bubble path shown in Figure 1.

It has been found in actual operation that by a providing a curved surface 36 at theinlet side of the' throat ring l8, the bubbles G tend to follow the curvature of the surface either entirely or for a portion of its length and then break away to rise upwardly in a curved path, as illustrated.

' By forming the surface 36 curved instead of flat, 7

the bubbles G tend to follow the curvature of the surface after they break away from actual contact therewith thereby effecting a' funnel-shaped path of greater width at the bottom of the tank ill than would. be effected if the surface were I made flat and extended diagonally upward and outward. It has also been found that some of the bubbles G tend to be trapped, between the overlapping portions of the bottom surface of the throat ring it and the flat edge of the ,As the impeller I9 is revolved at high speed, "a high suction is built up back of each of the revolving blades which causes the generation of additional bubbles of -gases or vapors to be liberated from the liquid fuel flowing through the pump .into the volute chamber thereof. high suction back of the revolving blades causes a cavitation oranopen yspacezwhich is free of liquid fuel.. By increasing the throat opening immediately above the impeller blades by the This whereby fully liquid fuel only flows into the volute chamber l6.

- When an aircraft isflown to an altitude wherethe fuel in the pond P starts breaking up because of the reduced pressure, scattered bubbles may appear throughout the tank,' but as explained above, such bubbles are separated from the liquid fuel, -sothat only fully liquid sured into the fuel line 32.

' In flying aircraft to high altitudes, the booster 'piunp H can be started before the fuel starts breaking, up in the pond, so .thatthe fuel will become stabilized even at the sub-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 fuelfrom the pond to the fuel line.

By immediately pressuring thebubble-free fuel in the volute chamber and by holding .this pressure above the vapor pressure of the fuel-throughout the entire path of flow of the liquid to the engine carburetor, .additional gases "or vapors cannot be liberated.

While, as illustrated in Figure 1; it is preferred to mount the booster pump II on the bottom of the tank ill, in some installations it may be necessary to mount the pump H on the side wall of the tank. It is only necessary that the impeller be so mounted as to lie below .the hydraulic gradient of the pond P. When so positioned,,the

fuel pressured by' the impeller into the volute chamber l6 will be free from entrainedgases or vapors.

From the'foregoing description, it will be apparent that the booster pump described has two functions: the first, to separate out bubbles of gas or vapor which form at the inlet, due to the This additional opening of the throat results in a greater cavitation and causes In other words, the

material. is presnecting an end surface of said ring.

' to said end surfaces.

agitation of the liquid, and elsewhere in the tank; and the second, to pressure the fully liquid fuel to a fuel line. The improved inlet throat construction of this invention for such a booster pump increases the gas and vapor separation efliciency of the pump while maintaining fuel pressuring efficiency for the pump. Furthe more, this greater efiiciency is effected without the need for providing additional power for maintaining the agitating speed "of the impeller.

While a particular embodiment only of this invention has been illustrated, it will, of course, be understood that the invention should not be limited thereto, since many 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.

I claim as my invention: I

1. In a pump having a driven impeller with vanes radiatingoutwardly toward the periphery thereof, the improvement of aninlet throat for said pump comprising a ring member having its whole inner periphery formed by curved surfaces extending outwardly in opposite axial directions toward the end surfaces thereof, one of said curved surfaces being described by a greater radius than the other of said curved surfaces, said ring member overlapping the periphery of said impeller in closely spaced relation therefrom with said other and shorter curved surface lying adjacent said vanes.

2. In a pump having a driven impeller with vanes radiating outwardly toward the periphery thereof, the improvement of an inlet throat for said pump comprising a ring member overlapping the periphery of said impeller in closely spaced relation therefrom, and means for removably securing saidring member to said pump, said 'ring member having its whole inner surface formed by tangentially connected circle arcs of different radii, one of said arcs tangentially con 3. An inlet throat for a pump comprising a ring member having a bore thcrethrough, said bore being formed of tangentially connected circle arcs of different radii extending in opposite axial directions toward the end surfaces of the ring member and being tangentially connected 4. An inlet throat for a pump comprising a ring member having a bore therethrough; said bore being formed of tangentially connected circle arcs of different radii having their centers lying in a single transverse plane, said circle arcs extending outwardly in opposite axial directions toward the end surfaces of the ring member and being tangentially connected thereto.

5. An inlet throat for a pump comprising an annular member having an axial bore there through and a radially extending flange on the outer periphery thereof, said flange having oir-' cumferentially spaced axially extending'screw receiving openings therethrough for removaably connecting the member of the pump, said throatmember having spaced end faces, and said axial bore being defined by tangentially connected circle arcs of :different radii extending in opposite axial directions toward said end faces and tangentially terminating in connection therewith.

6. In a centrifugal pump having a driven im-' peller with a radial disk and upstanding curved anes thereon radiating outwardly toward the periphery thereof, each of said vanes having an which comprises a ring member overlapping said impeller in closely spaced relation therefrom and having an internal bore lying between the outer ends of said vanes and their sloping edges, said internal bore being defined by circle a cs of different radii extending outwardly in opposite axial directions toward the end surfaces of said ring member, the circle arc of smallest radius extending toward said overlapped vane portions.

7. In a centrifugal pump having a driven impeller with a radial disk and upstanding vanes thereon radiating outwardly toward the periphery thereof, each of said vanes having its upper edgesloping inwardly from substantially its midportion toward the axis of the impeller disk and having its upper edge at the outer portion thereof substantially parallel with said disk, the improvement of an inlet throat for said pump comprising a ring member having an internal bore and an end surface in closely spaced parallel relation with the upper edges at the outer portions of said vanes, said internal bore lying between said inner and outer portions of the upper edges of said vanes whereby the throat ring overlaps said vanes for substantially one third of their lengths, said bore being defined by connected curved surfaces of different radii extending outwardly and in opposite axial directions, the curved surface of smallest'radius extending toward said overlapped vanes.v

8. In a centrifugal pump having a driven impeller for agitating a gasifying source of liquid at its inlet to beat bubbles of gas from the liquid and deliver fully liquidfuel to its outlet, said impeller including a radial disk and curved vanes thereon radiating outwardly toward the periphery thereof, the improvement of a removable inlet throat' for said pump comprising a ring member having an internal bore of less diameter than said impeller for partially overlapping the vanes thereon,v said internal bore being defined by connected curved surfaces extending outwardly in opposite axial directions toward the end surfaces of the ring member, said curved surfaces being described by different radii with the curve of greatest radius opening into said gasifying source of liquid and thecurve of smallest radius extending toward said overlapped vanes whereby rota-' vanes thereon defining pumping channels communicating with the volute chamber, the improvementof an inlet throat for said pump overlapping the outer portions of said vanes in closely spaced relation therewith to define a Wall for said pump channels, said throat defining an inlet opening to the pumping channels and said opening initially converging along a curved path and then diverging radiall along a curved path to the inner ends of the pumping channels to facilitate release of bubbles from the channels,

WILLIAM J. LOCKET'II.

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