US2319229A - Fuel pump - Google Patents

Description

May 18, 1943 Filed Aug. 25, 1941 L. B. HARRINGTON FUEL PUMP 3 Sheets-Sheet l Zmnentor ,zcis'ar l i ar riryfon FUEL PUMP Filed Aug. 25, 1941 3 Sheets-Sheet 2 lmventor Zasr B. fiai'rizylzm Bu Q M May 18, 1943 a. HARRINGTON 2,

' FUEL PUMP Filed Aug. 25, 1941 3 Sheets-She et 3 m A v .m A, W, PM! 3% h $2 .7/ a A ,.Y mI I M W Z/////// WMWW W W -iflufl I k i M l k Patented May 18, 1943 UNITED,,STATES PATENT OFFICE FUEL PUMP Lester B. Harrington, Salem, reg., assignor of forty per cent to Reynolds Allen, Salem, and fifteen per cent to Clay A. Racely, Portland,

Oreg.

Application August 25, 1941, Serial No. 408,257

9 Claims.

The present invention relates to improvement in fuel pumps, and has for an object to adapt to the fuel systems of oil burning furnaces and casing or housing.

It is another object of the invention to so isolate the rotary impeller of the pump as to withdraw it to a maximum degree from friction losses which would otherwise be encountered where the impeller is left to rotate in the main body of the fuel liquid in the reservoir up into which the liquid fuel is pumped from a submerged supply tank and from which such liquid fuel flows by gravity to the oil burner. g

A further object of the invention is to so house in a secondary casing the rotary member of the pump as to avoid its rotation directly in contact with the main body of fuel in the reservoir to the end that turbulence in the main body of the fuel is avoided; and to the further v purpose that a quiescent condition in. the main body of fuel in the reservoir will contribute to greater fidelity and constancy of performance in the switch-float mechanism which controls the circuit to the pump driving motor.

A still further object of the invention resides in providing an improved fuel pump in which the wall of the secondary casing concentrically opposite the periphery of the impeller through i which the liquid is discharged is constructed on a volute curve progressing toward its widest radius out the outlet of the casing, namely from that part dfithe casing which leads directly into the reservoir and from which the liquid is evacuated from the pump into such reservoir; for the purpose and to the end that the volute wall will restrict to a minimum the quantity of ac- Astill further object of the invention is to secure and promote quietness in the operation of the pump by reducing the liquid turbulence and restricting the volume of liquid subject to such turbulence incidental to pump operation.

A still further object of the invention is to rovide a compact organization of pump reservoir, motor and its control mechanism designed for economical manufacture, easy installation and ready accessibility for making replacements or repairs.

With the foregoing and other object in view, the invention will be more fully described hereinafter, and will be more particularly pointed out in the claims appended hereto.

In the drawings, wherein like symbols refer to like or corresponding parts throughout the several views.

Figure 1 is a central vertical section taken through the reservoir casing with the pump, its driving motor and switch-float control shown in elevation.

Figure 2 is a horizontal section taken on the line 2-2 in Figure 1.

33 in Figure 1.

Figure 4 is a bottom plan view of the secondary or pump casing with the bottom cover removed and the rotor shown in section. Figure 5 is a transverse section taken on the line 55 in Figure 4.

Figure 6 is a vertical section taken on the line 6-4 in Figure 5. v

Figure 7 is a diagrammatic view showing the relation of the improved device to the burner and submerged fuel tank.

Figure 8 is .an enlarged, schematic view. showing the progress of the liquid through the impeller passages.

Referring more particularly to the drawings.-

lll designates the casing of the reservoir which cessible liquid driven around in the secondary casing by the rotary action of the impeller, and which in this way reduces the liquid drag on the impeller and thereby allowing it to rotate more rapidly on a given amount of power, and also permittingthe pump operation with a greater conservation of energy.

furnace to provide for gravity flow from the reservoir to the burner'through the conduit l2..

The reservoir is supplied from a submerged tank l3 through a pipe II; the lift being secured by the vacuum pump which is installed within the reservoir III in an independent secondary casing l5. This casing is or may be composed generally of a side wall IS an outer wall l1 and a cover plate l8 removably attached, as by suitable fastenings l9, to the outer wall I! or other part. The outer wall I! is constructed on a volute curve, the greatest radius of which coincides substantially with the outlet port 20 which Figure 3 is a similar view taken on the line opens directly and unimpededly into the surrounding body of fuel liquid contained in the reservoir ID.

The rotor or rotary member of the pump is indicated at 2| and is constructed with one or more liquid passages, two such passages arranged substantially diametrically opposite being illustrated as a preferred arrangement.

Each passage is composed of three components: an orifice 22 of a diameter smaller than that of the remainder of the passage and sufilciently small to produce a vena contracta 23 in the abruptly enlarged chamber 24 which forms the second component of the passage. The orifice 22 is of very small axial length as compared with the overall length of the passage and such orifice 22 is located very close to the center of rotation of the rotary member 2|. In fact the orifice 22 is located substantially at the center of the impeller save for a small central space concentrically in alinement with the passage into which the propelling liquid of the pump is drawn from the main body of liquid in the reservoir Ill through a small eye or opening 26 centrally of the cover plate l8. This eye or opening 26 has arestricted diameter or a restricted port area which confines the entrance of. propelling liquid to the rotor or impeller in a local manner to the eye of the impeller, the cover plate It acting to exclude from the impeller the liquid which forms the body in the reservoir Ill. In other words the secondary casing segregates and isolates the rotary element of the pump from any general and complete communication with the great body of the liquid fuel in the reservoir it, which lack of accessibility of the rotary member to such body of liquid has two advantages; first, it prevents agitation or turbulence in the main body of liquid in the reservoir Ill occasioned through mechanical churning by the rotary action.of the impeller, and leaves this body of liquid quiescent to respond more readily to liquid level changes as affecting the operation of the float switch hereinafter more fully described, and secondly, the secondary casing prevents those high friction losses which would accrue were the impeller submerged directly in the body of the reservoir liquid. By confining the entrance to the impeller of the propelling liquid from the supply of fuel liquid in the reservoir It in the manner secured by the eye or opening 26, the stream of incoming propelling liquid is localized to the small central space 25 by which it communicates with the inner ends of the orifices 22.

The third component of the liquid passage in the rotor is the distal portion 21. In comparison to this distal portion the orifice 22 may be described as the proximal part of the passage. The distal portion 21 extends from the periphery of the disc or rotor 2| continuously in to the enlarged chamber 24 with which it merges. The combined chamber 24 and distal portion 21 do not narrow at any'part from the orifice outwardly but preferably flare although within limits and to a slight extent, The cross-sectional area of the distal portion 21 must throughout its length be within the limits which will produce a pump action which requires that the liquid received from the vena contracta 23 shall expand in all directions radially of the wall of the distal portion 21 and in suflicient mass and volume to form an effective seal for two purposes; namely to present a body of liquid in the distal portion 21 outwardly of the enlarged chamber 24 which under the rotation of the impeller is being sub- 75 jected to acceleration due to centrifugal force, and which is thereby exerting a high suction upon the area in and about the vena contracta 23 thus creating a low pressure area by the pump action which is in addition to that produced by the vena contracta in the same area; and secondly the liquid in the distal portion 21 prevents atmospheric pressure from rushing into the low pressure area inchamber 24 to relieve and break the vacuum in a reverse stream from the outer peripheral end of the passage inwardly to such chamber 24. Therefore any flare given the distal portion 21 will not be in excess of the requirements of the pump and the vacuum seal. Such flare and the cross-sectional area of the distal portion 21 at any point will of course depend upon the cross-sectional area of the orifice 22 which primarily controls the amount of the propelling liquid fed to the vena contracts, the vena contracta in turn feeding the pump distal portion 21 of the passage. Of course rotor speed is another factor entering into such relative cross-sectional area sizes. The orifices 22 must at all times be sufficient in cross-sectional area to supply to the distal portion 21 propelling liquid in sufiicient volume to cause the seal and the pump operation.

The body of fuel in the submerged tank I3 is subject to low pressure. area in the enlarged chamber 24 through the pipe I4 being connected with the passage 28 in the pump support bracket 29, which passage communicates with an annular channel 30 formed about the impeller shaft 3| in its bearing 32. which bearing may be a part of the bracket 29. The impeller shaft 3i is provided with one or more radial ports 33 which communicate with the bore 34 of the shaft. Such bore leads to a recess 35 between the collar 38 and the impeller disc. This recess 35 communicates with ports 31 in the impeller disc which connect with the low pressure chambers 24 of all the passages.

It will also be noted that the passages, while generally radial are curved to radii of the impeller disc in a rather wide sweep in which the curvature is away from the direction of rotation of the impeller. This causes the liquid in the distal portion to leave the periphery of the impeller more toward a perpendicular to the passage which has a tendency to preserve, and not to reduce, the sealing engagement of such liquid with the walls of the distal portion.

The orifice 22 will be such a sharp edged orifice on its inner'end as to project a vena contracta radially outward of the outer part of the orifice and into the enlarged chamber 24. The enlargement of the passage at the chamber 24 concentrically surrounding the vena contracts provides sufiicient annular space in the passage which is mechanically free of the vena contracta. as compared for instance with the constricted part of the Venturi tube. Also unlike the Venturi tubev access to the low pressure area by the lifted liquid entering through ports 31 is to this circumambient space rather than directly and immediately to the actual fluid embodied in and forming the vena contracta by which I secure two results, namely first, the direct entrainment of the pumped liquid received through ports 31 into the high velocity stream in the vena contracta. and secondly the pull of the pump sealing liquidin the distal portion, which is moving out at accelerated. speed due to centrifugal force, which pump liquid has direct and immediate access to the said low pressure circumambient space independently of the vena contracta. Therefore the lift of the pump or the degree of vacuum formed thereby is rated as to two factors, namely the pump and the vena contracta and both of these factors are superimposed upon one another and act additively upon the same low pressure space which is that confined in the enlarged chamber 24.

The abrupt enlargement of this chamber in juxtaposition to the outer end of the orifice 22 allows of this vena contracta, unrestrained in its formation by any external constricting wall as in the venturi, to be formed in accordance with hydraulic principles as a hydraulically sustained projected rapidly moving liquid through such enlarged chamber independent of any support from the chamber and thereby providing the circumambient space referred to which communicates at once with the vena contracta and the pump volume of liquid in the distal passage.

The impeller shaft 3| at its-outer end is fixed to an end of a spring shaft 38 the opposite end convolution 39 of which is carried diametrically across the helix in position to be detachably re- .ceived by a fork 4|] in the lower end of a motor shaft 4| driven by the electric or other motor 42. This arrangement permits the motor and its shaft 4| to be lifted off and disconnected from the spring shaft 38.

The motor may bemounted upon a motor installation plate 43 carried removably in the reservoir, as for instance being supported removably upon angle iron or other brackets 44, being secured detachably thereto by screws or other fastenings 45.

Carried upon the installationplate is also a fuse block 46 to which the leads 41 are connected for bringing the current into the motor from the mains or other appropriate source. In the motor circuit is a mercury switch 48 carried by a float 49. The float 49 is pivoted at 50 to a support 5| depending from the fuse block 46 or from the plate 43. The float is intended to ride upon the surface of the liquid body of fuel in the reservoir l0 and to assume a predetermined angular position when the level of the fuel is at a selected height in the reservoir such as will maintain on hand the requisite fuel or fluid body in the reservoir for the needs of the burner.

In this normal upper position of the float 49 the mercury switch is arranged to be in open position. As soon as the liquid level in the reservoir I0 declines below this specified height the float 49. descending with such liquid, will tilt about the pivot 50 causing the mercury to close fhe contacts and the motor circuit, thus establishing pump operation. In this way the action is automatic, the .float and its mercury switch closing and alternately opening the circuit to the motor 42 and as a consequence maintaining a constant level of liquid fuel in the reservoir.

The reservoir and the unitary motor and float installation may be all protected by a removable cover 52 held in place removably by screws or other fastenings 53 having attachment also to the angle iron or other brackets 44. A check valve 54 is located somewhere in the pipe line H. which check valve functions to preventthe free running flow of the liquid from the reservoir back into the submerged tank It! when the pump operation is stopped. This check valve will preferably be in a vertical sectionof the pipe l4 and be without spring, closing under the influence of gravity alone.

In operation, viewing the device as a vacuum pump per se, it will be understood that the enlarged chamber 24 and the distal portion 21 enable the liquid which has undergone an increase in velocity due to its flow through the orifice to slow down and to convert that velocity into pressure which is manifested in the distal portion by the spread of this liquid in large volume radially outward in all directions against the walls of the distal portion, this' being one of the contributing factors toward an extremely high seal.

One object of the volute casing is to recirculate the liquid in the impeller in the most efilcient manner with the least losses 01' energy due to the restricted volume of liquid by the volute housing restricted at the center of the volute housing known as the inlet of the cover plate whereby a limited supply of liquid is allowed to enter and discharge through the impeller with a minimum of, loss of energy.

As the rotary member rotates within its secondary casing it draws in locally through the eye or opening 26 in the cover the liquid from the reservoir and projects such liquid into a vena contracta and discharges the liquid at the outer periphery of the impeller. Such liquid is then moved against the volute wall of the secondary casing, which changes its velocity to pressure and moves it in a quiet manner through'the outpelling liquid through the pump is a pull on the downstream side of the vena contracta.

Although I have shown in Figure 5 and 6 a construction in which the cover plate I8 is spaced below the rotary impeller 2|, it will be understood that the end wall I! of the secondary casing l5 may be of such depth that the cover plate I 8 will fit substantially up against the lower side of the rotary member 2|, in which event the restricted central port 26 of the cover I8 will form a substantial continuation of a like central restricted port 26a in the rotor 2|.

It is obvious that various changes and modifl flcations may be made in the details of construction and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims.

What is claimed is:

1. In a device as described, a reservoir for containing a body of liquid, a pump impeller located below the level line of liquid in said reservoir and having a passage therein composed of means for forming a vena contracta and means for accelerati-ng the liquid issuing from the vena contracta, a casing for said impeller having a volute internal wall opening at its large end into the liquid space of a reservoir and closed at its smaller end said casing having a restricted opening to the liquid space of the reservoir and to the inner end of said passage.

2. In a device of the kind described. a reservoir for holding a body of liquid, a pump for raisne liquid to said reservoir comprising a rotary impeller having a passage therein havingas com- Thus volute wall leading from its narrowest closed.

radius to said discharge'point, and an inlet in the casing for introducing liquid from the reservoir into the eye of the impeller at the central portion thereof.

3. In a device of the character described, a reservoir for liquid fuel oil and the like,- a thin, flat pump'casing immersed in the body of liquid oil in said reservoir and having an internal volute wall leading to an open discharge port substantially at its widest portion by which the contents of the casing is discharged into the reservoir below the upper surface thereof, said casing having at its central part an inlet port opening between the reservoir and casing, a rotary impeller in said casing having a passage therein communicating at its inner end with the body of liquid in the reservoir solely through said .restricted inlet port, said passage formed of a substantially central oriflce having a sharp inner wall and being of restricted cross-section inform a vena contracta. an abruptly enlarged chamber extended in spaced relation about said vena contracta, and a long distal portion extending from the chamber out to the periphery of the impeller concentrically opposite said volute wall, a bearing in the reservoir for supporting said casing and impeller and having a conduit therein communicating with said enlarged chamber and with a source of external liquid fuel supply from. which the reservoir is replenished by action of said pump, a shaft extending through said bearing, and a motor having a demountable connection with said shaft, a circuit to said motor, a movable float in said reservoir, and Ya normally open switch in the motor circuit closed automatically when the float lowers incident to declining liquid level in the reservoir.

4. In a device of the character described, a

reservoir for liquid, 9. supply source at a lower level than said reservoir, a pump impeller in said reservoir, a casing for said pump impeller segregating the internal-casing space subject to impeller action from the main liquid space of said reservoir, said casing having a restricted liquid inlet in communicating with the liquid space of the reservoir, to admit liquid from the reservoir only restrictly to said casing and locally to said impeller,- said casing having a discharge from the impeller to the liquid space of the reservoir, said discharge being of progressively greater diameter toward the liquid space of the reservoir to convert velocity of the impeller liquid into pressure in the discharge, liquid entraining means in said impeller communicating with-said supply source, electric motor means for driving said impeller, and switch float means in said reservoir for controlling the action of s'aidimpeller driving means.

5. In a device of the kind described, a reservoir for containing a body of liquid at constant level, an outflow from said reservoir for consumption demands, a source of liquid arranged below the level of the reservoir, a pump in the reservoir submerged below liquid level therein for raising the liquid from said source to said reservoir, said pump comprising a casing having an internal impeller space segregated from the main body of liquid in said reservoir, and a rotary impeller in said casing, electric motor means to drive said impeller, a float switch in the reservoir controlling the action of said drive means, said impeller having a passage therein communicating restrictedly at its central portion with the liquid space of said reservoir to provide propelling fluid to the propeller, means for connecting said source with the impeller passage ofl! center impeller axis of rotation, said casing having an outlet for conveying discharged propeller liquid into the surrounding liquid space of the reservoir, said discharge being of progressively increasing area to convert the velocity of the propeller liquid into pressure before discharge into the reservoir.

6. In a device of the kind described, a reservoir having a liquid body therein, an outflow ,from said reservoir to consumption uses, a source of liquid supply at a lower level than said reservoir, a pump in said reservoir for raising the liquid from said source of supply, an electric motor for driving said pump, a float switch in the reservoir for automatically controlling the starting and stopping "and the operation of said motor, saidpump comprising a casing and an impeller therein connected to be driven by said motor, said pump being submerged below constant liquid level insaid reservoir, said casing having a restricted liquid inlet at a central portion thereof communicating with the internal liquid space of the reservoir and having an enlarged liquid outlet discharging directly into the liquid space of the reservoir, said impeller having a passage therein comprising a central chamber in restricted communication with the liquid space of said reservoir, an orifice extending out from said central chamber, an abruptly enlarged chamber outwardly beyond said orifice and a distal portion of progressively increasing diameter from said enlarged chamber to the rim of the impeller, and means for connecting said source with said'enlarged chamber of the passage.

7. In a device of the kind described, a reservoir for a body of liquid, a liquid source at a lower level, a pump submerged in the liquid in said reservoir comprising a rotary pump element and a casing segregating the element from the liquid body in said reservoir and having a gradually enlarged outlet opening into the liquid space of the reservoir, said rotary element having a passage therein communicating restrictedly at its inner portion with the liquid in said reservoir and opening at its outer end to the internal casing space, said passage having means for forming a vena contracta, and means connecting said source with the space about said vena contracta.

8. In a device of the kind described, a reservoir for containing liquid, 9. source of liquid below the'level of said reservoir, and a pump in said reservoir for raising the liquid from'said source and comprising a rotary impeller and a casing extending about said impeller and segregating the impeller from the liquid in said reservoir, said impeller having a passage therein comprising a central space, an orifice outwardly of and communicating with said space, a chamber of enlarged diameter over the diameter of the orifice communicating with the orifice at the outer end of said orifice, and a distal portion leading from the chamber to and through the rim of the impeller and being of progressively increasing cross sectional area from the chamber'to said rim, ports of restricted area in the casing and impeller to place the central space of the passage in communication with the liquid space of the reservoir, and means connecting said liquid source with said enlarged chamber, said pump casing having an outlet communicating directly with the liquid space in the reservoir.

9. A device according to claim 8 characterized by the fact that the discharge of the casing is produced by a volute casing wall concentric with the impeller rim and being of largest radius at 5 the point where the discharge empties into the liquid space of the reservoir.

LESTER B. HARRINGTON.

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