US2494086A - Pump entry vane construction - Google Patents

Description

Jan. 10, 1950 R. R. CURTIS PUMP ENTRY VANE CONSTRUCTION Filed Nov. 29, 1943 1/9 7271 Russell R. Curtis.

Patentecl Jan. 10, 1950 PUMP ENTRY VANE CONSTRUCTION Russell R. Curtis, Dayton, Ohio, assignor, by mesno assignments, to Thompson Products, Inc., a corporation of Ohio Application November 29, 1943, Serial No. 512,263

4 Claims.

1 This invention relates to a device for breaking up a vortex of whirling liquid at the inlet of a centrifugal type pump.

Specifically the invention relates to an entry vane and filter screen assembly for centrifugal type booster pumps adapted for use in an airplane fuel system.

The invention will hereinafter be specifically described in connection with airplane fuel systems, but it should be understood that the invention is not limited to such use, being broadly applicable to any system embodying the use of centrifugal type pumps or other devices which tend to whirl liquid.

In airplane fuel systems having centrifugal type booster pumps equipped with agitators or beaters for liberating bubbles of gas and vapor from fuel entering the pump, there is a tendency for the fuel flowing to the pump to form a whirling vortex especially if the fuel is directed to the pump through a conduit that is not much larger in diameter than the diameter of the pump inlet. In such systems the liberated bubbles of gas and vapor should rise around the liquid flowing to the pump and eventually reach the surface of the pond of fuel where they can burst to discharge the gases and vapors. A whirling vortex of fuel fiowing downwardly to the pump, however, may trap the rising stream of bubbles, thereby building up a layer of bubbles or a slug of vapor which might eventually find its way into the pump. Since such a slug of vapor offers very little resistance to the pump, the impeller speed of the pump increases over its normal speed and results in increased agitation tending to disperse the gases or vapors back through the inlet of the pump. Such dispersement, of course, permits the liquid fuel to again flow into the pump whereupon the impeller speed will be reduced. Thus slugs of liquid and pockets of gas or vapor are alternately acted upon by the impeller and pulsations occur in the pump speed with resulting pulsations of the liquid fuel pressured by the pump. Such alternate pumping of gases and vapors is, of course, highly undesirable in fuel systems where a supply of fully liquid fuel under constant pressure must be maintained for efficient operation.

According to this invention, a baille is mounted in the inlet of the pump and extends for a considerable distance into the liquid about to enter the pump. This bafiie has broad opposed side faces effective for breaking up the whirling of the fuel so that the liquid will be directed axially into the pump. Since it is also desirable to screen or filter the liquid being fed to the pump, this baflie is conveniently carried by a cup-shaped screen mounted over the pump inlet. The balile projects from the mouth of the cup-shaped screen into the throat opening or inlet opening of the pump where it terminates in closely spaced relation to the pump impeller. Thus the projecting portion of the baflle will prevent the formation of a secondary whirlpool within the pump inlet.

It is, then, an object of this invention to provide an entry vane construction for centrifugal type pumps which is carried by a screen or filter adapted to be mounted on the pump.

A still further object of the invention is to provide a combined filter and bailie construction for centrifugal type pumps.

Another object of the invention is to provide an attachment for centrifugal type pumps which will effectively prevent whirling of fuel about to enter the pump.

Still another object of the invention is to provide an entry vane construction for booster pumps which is readily mounted on said pumps without change in pump construction.

Other and further objects of the invention will be apparent to those skilled in the art from the following detailed description of the annexed sheet of drawings which, by way of preferred example,-illustrates one embodiment of the invention.

0n the drawings:

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

a booster pump, a fuel tank, and a fiow connec-' tion therebetween, illustrating the entry vane and filter construction of this invention mounted on the booster pump.

Figure 2 is a fragmental vertical cross-sectional view, with parts in elevation, taken along the line IIII of Figure 1.

Figure 3 is a bottom plan view of the filter and entry vane construction according to this invention.

As shown on the drawings:

In Figure 1 the reference numeral Ill designates a tank having a vent II and holding a pond P of gasoline or other volatile engine fuel. A booster pump assembly I2 is connected in fiow communication with the tank ill by means of a pipe member l3. This pipe member I3 is formed as an elbow with one end being connected to a side wall ll of the tank adjacent the bottom wall l5 of the tank. The elbow type flow connection between the tank In and booster pump assembly I2 is used in installations which do not have sufflcient pump mounting space immediately adjacent the tank. It is preferable to mount the pump i2 directly on the bottom wall ii of the tank but in some installations the bottom wall of the tank is not spaced sufficiently from an airplane wing skin, or the like to provide room for the pump.

The elbow pipe l3 has a radially outturned flange ii at the lower end thereof. The pump l2 includes a casing i1 defining a pump volute chamber IS, a discharge outlet l9 communicating with the volute chamber I8, and a shaft well 20 receiving therethrough a drive shaft 2i. An electric motor or other prime mover (not shown) drives the shaft 2|. The casing 11 has an outturned flange 22 therearound receiving bolts 23 therethrough having heads seated on the flange ii of the elbow pipe l3 and nuts 23a thereon underlying the flange 22 to mount the pump assembly I2 on the pipe l3. A gasket 24 is preferably interposed between the flange l3 of the pipe l3 and the flange 22 of the pump casing.

The casing l1 has an annular open end communicating with the volute chamber I8 through a cylindrical bore 25 and terminating in a flat end face 25.

A throat ring 21 is mounted in the bore 25 and has a radial flange 28 snugly fitting into the pipe l3 and seated on the end face 26 of the casing l1.

The throat ring 21 has an outwardly flaring conical mouth 29 cgnverging to a circular opening 30 of smaller diameter than the bore 25 so that the bottom of the ring forms a top wall for the volute chamber it. The opening 30 forms the inlet to the pump.

An impeller 3| is mounted on the shaft 2!. This impeller is preferably in the form of a hubbed disk with a hub 3la secured on the shaft 2| and a flat disk portion 3") spanning the opening 30 and overlyingthe shaft well 20. Upstanding vanes 32 are formed on the disk portion 3"). These vanes 32 have outer end portions 32a underlying the throat ring 21 to cooperate therewith for forming pumping channels between the opening 30 and the volute chamber l8. The vanes will centrifugally pump fuel to the volute chamber l8 and through the volute chamber to the discharge line It.

The vanes 32 also have inner end portions 32b under the opening 30 of the throat ring 21 where they are fully exposed and are uncovered. The inner ends 32b of the vanes 32 serve as agitators or heaters for liberating bubbles B of gas and vapor from the fuel before the fuel enters the pumping channels. flow outwardly along the diverging mouth 29 of the throat ring 21. The pump is arranged so that onlyfully liquid fuel is pressured and so that vapors and gases are rejected from the pump to flow away from the pump in bubble form.

In accordance with this invention a cup-shaped metal screen 35 is provided to filter fluid flowing into the pump. This screen 35 has a cylindrical side wall 36 of large enough diameter to surround the divergent end of the mouth 29 of the throat ring 21. The side wall 38 projects for a considerable distance in advance of the pump into the pipe l3 and a wire screen 31 bridges the end of the cylinder at a point remote from the pump.

The open end of the cylinder receives therearound a metal ring 33 having an upstanding flange 38a soldered or otherwise secured to the screen. This ring 38 is apertured at intervals therearound to receive the cap screws 39 therethrough. Thus cap screws 39 extend through the These bubbles of gas and vapor 4 flange 23 of the throat ring 21 and are threaded into the casing "to hold the screen assembly and the throat ring on the casing [1.

The screen assembly 35 is readily made by soldering the mounting ring 38 around one end of a screen cylinder and by pressing a screen disk 31 into the other end of the cylinder to leave a. flange 31a on the disk abutting the inner face of the cylinder. This flange is then conveniently soldered or otherwise secured to the cylinder.

A baffle or vane 40 preferably composed of a metal sheet or plate is disposed in the cylinder 36 to lie axially along the length of the cylinder for dividing the chamber provided by the cylinder into two adjacent compartments each of which communicates at its lower end with the opening 30 of the throat ring. This vane 10 is conveniently soldered to the cylindrical wall 36 and extends from closely spaced relation from the end wall 31 out of the open end or mouth of the screen. The projecting portion of the plate has tapered edges 40a in spaced parallel relation with the outwardly flaring wall 29 of the throat ring so that the end of the plate can lie immediately adjacent the opening 30 of the throat ring.

A screen cup assembly carrying a dividing plate or baffle is thus provided for mounting on the inlet throat of a booster pump so that the plate will project into the inlet throat and terminate in closely spaced relation to the impeller of the p mp.

Fuel can flow freely from the tank Ill through the pipe [3 and through the pump I2 to the discharge outlet l9 thereof even when the pump is at rest since the inlet 30 and the outlet IQ of the pump are in constant communication. When the pump is operated the outer portions 320: of the vanes 32 on the impeller 3i will centrifugally discharge fuel through the volute l8 into the discharge line I9 while the inner pumping vane portions 32b exposed to the inlet opening 30 will beat out bubbles B of gas and vapor from the liquid fuel.

Rotation of the impeller 3|, however, may create a vortex or whirling mass of fuel in the pipe l3, the particles of which rotate in the same direction as' the impeller and move in a corkscrew fashion toward it. The bubbles B are thrown out by the vanes along the outwardly flared surface 29 of the throat 21 and, being lighter than the liquid fuel, rise within the vertical leg of the elbow member l3 adjacent the walls of this leg. The light bubbles of gas and vapor rising in the vertical leg of the elbow member tend to flow into the path of liquid flowing through the horizontal leg of the elbow member and tend to be drawn toward the impeller with the liquid fuel. A layer or mass of bubbles may thus form across the in- -let throat of the pump, cutting off flow of liquid into the throat and. permitting the impeller vanes to operate in a gas. This, of course, will speed up the pump by reason of the low inertia of the gas and vapor bubbles as compared with the inertia of the liquid fuel. Speeding up of the impeller creates additional agitation which forces the bubbles outwardly along the tapered surface of the throat ring, thereby breaking up the pocket of the vapor and gas. As soon as this pocket is broken up a slug of liquid fuel will then flow into the inlet throat and the speed of the im peller will be reduced by the inertia of the liquid. As a result, alternate formation of vapor pockets and beating of slugs of liquid, together with alternate variations in impeller speed, causes pulsations in the delivery of fuel to the outlet I9 of the pump.

This pulsating delivery is prevented by the baiiie 40 which extends into the pipe IS in advance of the inlet 30 of the pump and provides wide faces for breaking up the whirling mass of fuel adjacent the pump inlet and for directing the fuel axially into the pump inlet. The baflie 40 does not restrict the separation of gas and vapor bubbles from the liquid fuel caused by the agitating impeller vanes and the bubbles are thrown outwardly along the outwardly flaring walls 29 of the throat ring where they will rise the screen and having the outwardly flaring mouth of the throat in upwardly as shown in Figure 1 around the de- I scending column of liquid fuel. A countercurrentcirculation of fuel and bubbles is thus created in the elbow member I3 with the bubbles rising through the fuel adjacent the walls of the elbow member and with the fully liquid fuel being fed axially toward the impeller to the inlet throat. The screen 35, of course, filters out any solid matter such as dirt, rust, and the like and prevents the same from reaching the The screen and vane construction is readily mounted on any type of pump and the pump construction need not be modified.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. A fllter and vane construction for a centrii'ugal type pump having a tapered inlet throat which comprises a cup-shaped metalscreen, a mounting ring secured around the mouth of the screen for attaching the screen to the throat of a pump, and a vane in said cup-shaped screen dividing the screen axially and having a portion projecting beyond the mouth of the cup, said portion having tapered edge walls for lying closely adjacent the tapered inlet throat of the pump to provide an escape path along said tapered inlet throat of gas bubbles formed in the pump inlet.

2. In a pump construction including an inlet throat with an outwardly flaring mouth, an impeller having pumping vanes underlapping said throat to centrifugally whirl and pump fluid received from the throat together with uncovered agitating vanes exposed to the throat opening for acting on fluid 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 improvements of an inverted cup-shaped screen overlying the throat and having a mounting ring around the mouth thereof seated on top of the throat outwardly from the throat mouth, means attaching the mounting ring to the throat, and a baflle bisecting the cup-shaped screen secured to the side wall or close proximity to said throat mouth and to said agitating vanes, said baflle having side faces effective for breaking up the whirling of fluid flowing to the pumping vanes while directing the fluid substantially axially of the throat opening and permitting the escape of said bubbles of gas and vapor along said outwardly flaring mouth of the throat and through the screen.

3. In an assembly having a tank with an apertured wall and a booster pump mounted on said apertured wall having an outwardly flaring inlet throat in the aperture of the wall for receiving liquids from the tank, the improvements of an inverted screen cup overlying said throat and extending into the tank for an appreciable distance, and an upstanding baiile plate in said cup secured to the side wall thereof and having a tapered end portion depending from the cup into the throat in close proximity with the outwardly flaring mouth of the throat to provide opposed broad faces for breaking up whirling of fluid about to enter the pump while directing fluid in the cup axially into the pump.

4. In an assembly having a tank with a pipe extending from the lower portion thereof and having a free end with an outturned flange therearound, and a booster pump having an open topped pump casing with an outturned flange therearound clamped to the outturned flange of the pipe,-theimprovements of a conical mouthed throat ringseated in the open top of the pump casing and having a radial flange snugly fitting into the pipe, an inverted screen cup having a mounting ring around the 'mouth thereof, means attaching the mounting ring to the throat ring to secure the cup to the throat ring, 'said cup projecting into the pipe for an appreciable distance to provide an inlet filter for the pump, and an upstanding baflle plate bisecting said cup and secured to the side wall thereof, said baflle plate having a tapered depending portion projecting beyond the mouth of the cup into close proximity with themouth of the throat ring.

RUSSELL R. CURTIS.

REFERENCES crrnn The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 546,219 Behr Sept. 10, 1895 820,439 Ray May 15, 1906 825,317 Haskell July 10, 1908 1,281,478 Antisell Oct. 15, 1918 1,714,784 Hollander May 28, 1929 2,225,111 Higgins Dec. 17, 1940 2,306,297 Curtis Dec. 22, 1942 2,340,166 Young et al. Jan. 25, 1944 2,361,747 Curtis et al. Oct. 31. 1944

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