US1065732A - Centrifugal pump. - Google Patents

Description

J. SGHNBIBLE.

GENTRIFUGAL PUMP.

APPLICATION FILED JUNE 18, 1912. 1,065,732. Patented June 24,1913.

Z SHEETS-SHEET 1.

J. SCHNEIBLE.

GENTRIFUGAL PUMP.

APPLICATION FILED JUNE 1s, 1912.

1,065,732, l y Patented June 24,1913` 2 SHEETS-*SHEET 2` UNITED STATES PATENT OFFICE.

JOSEPH SCHNEIBLE, OF CHICAGO, ILLINOIS.

CENTRIFUGAL PUMP.

To all coll-0mi 15 may concern Be it known that I, JOSEPH SCHNEIBLE, a citizen of the United States, residing at 122 South Michigan avenue, Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Centrifugal Pumps, of which the following is a specification.

My invention relates to an improvement in the class of centrifugal pumps employing closed or shrouded impellers for prevent-ing leakage through the clearance-space betweei'i 'the impeller and side-walls o-f the pumpcasing from the outer circumference of the impeller inwardly toward the intake or suction-pipe of the pump.

The closed impeller, as hitherto constructcd, is not adequately effective for the aforesaid anti-leakage purpose excepting in pumps of large capacity. 'Ihe attempt heretofore made, in centrifugal pumps of smaller capacity, to accomplish the aforesaid purpose of reducing to the minimum the quantity of such leakage, has been by providing between the impeller-shrouding and sides of the pump-casing a very close clearancespace leading to the suction-pipe connection and requiring t-he fluid, after passing through that space, to iow through a labyrinth of rims or rings 4provided to reduce it. I-Iowever, even with that construction the clearance-space loss is so great, that in determining' the dimensions of the impeller for any given pump, the quantity of such loss has to be taken into account, because that quantity passes through the impeller in addition to the fluid being discharged by the pump. Moreover, that construction renders multi-staging necessary, even though the pressure sought might readily be attained by the action of a single impeller, were it not for the fact that the greater' the difference between the pressure at the impeller-rim and the suction-pressure the greater will be the quantity of leakage.

The object of my invent-ion is to provide a simple construction of impeller-shrouding which shall effectively overcome the difficulty in preventing the leakage referred to; and this I accomplish by providing the sidewalls on the impeller-blades, forming the impeller-shroud, with spiral passages about their outer faces, with the effect hereinafter explained.

In the accompanying drawings, Figure 1 Specification of Letters Patent. Patgnted June 24, 1913 Application led June 18, 1912.

Serial No. 704,381.

shows a centrifugal pump embodying my improvement by a section on line 1 F ig. 2, with t-he impeller in elevation, and F ig. 2 is a diametrical sect-ion through the pump on line 2, Fig. l.

The pump-casing 3, which may be of the construction illust-rated or of any other desired construct-ion, need involve no features of novelty. It has the intake Ll at the apex of the conical section 5 of one of its heads, and the peripheral outlet 6, as usual in such pumps; and between the annular outlet chamber 7 and impeller the inner surfaces of the casing-heads are formed with corresponding annular shoulders 71. The impeller 8, formed with a series of curved blades 9, is secured at its hub 10 to the drive-shaft 11 journaled in a head of the casing pro-vided with a stufling-box 12 and a. standard or leg 13 to be bolted to a suitable bed for stably supporting the pump in its operative position.

On opposite sides of the impeller-blades are pro-vided, or cast integral therewith, annular walls 14, 14, to form the impellershroud; and they extend inwardly from the blade-tip extremities a comparatively-short distance toward the hub, or to any distance most suitable for their purpose. Similar spiral channels or passages 15, 15 extend about the walls 14 on their outer surfaces, describing courses running from the inner edges of the walls outwardly and in the direction opposite to the direction of rotation of the impeller, to form fluid-ways between the smooth sides of the casing-heads.

Relatively short vanes 16 are shown by dotted lines in Fig. 1 to be provided between the impeller-blades on the inner faces of the walls 14, but they are not novel and are not necessary for use with my improvement.

In operating the pump, the impeller, which revolves freely in the casing, in producing outward motion of the fluid, generates by the action of the entire cross-section of both outer surfaces of the shrouding suflicient force thereon between the pump-casing and impeller-shroud to counteract and thus prevent back-flow, (due to difference in pressure within the clearancespace between the shrouding` and pump-casing) of the fluid through the clearance-space 16 from the periphery of the impeller toward the center of the pump, while at the same time maintaining a counter-pressure throughout the clearance-space corresponding to the pressure set up b y the impeller-action.

As will be understood, in the operation ot a centritugal pump a constai'it increase ot pressure is produced on the tluid as it moves radially troni the z Xis toward the iinpellerrim, where the pressure reaches its highest point. This is due to the constantly increasing rotating` velocity of the outwardly, and, con'iparatively, slowly moving tluid; and in consetpience of this di'l'lerence in pressure, the iluid tends to How through the clearance-space lauzkwardly toward the suctionpipe, causing the loss referred to, which inipaii's the etlicii-incy ot the pump and constii tutes the so-called clearance-space loss. This my iiiiprcveinent prevents, as aforesaid, because it` renders unnecessary close clearance between the rotating impeller and the suction-pipe; and since the outwaiL'dly-impelling force set up 'in the clearance-space at both sides of the impeller necessarily takes place near the impeller-riin, the walls 'ist need not. extend inwardly farther than is required to properly shroud the blade-tips, and a wholly unoliistructed entrance to the iinpeller is aliorded, which leaves the iimei' portion of the pun'iijiing chamber tree from any inipeller-casing and thereby almost totally avoids axial thrust, because et' the equal pressure within the part of the pumpcasing in which the impeller rotates.

lt should be emphasized that the shrouded impeller, in the present case, is not, in etl'ect, a siippleinentary pumping medium operating to torce the fluid in the clearancespace into the discharging tluid by overcomingl the back-pressure resistance ot' the latter; but that it operates to create and maintain in the clearance-space a iliractically constantI pressure, as an equilibrium to the back-pressure ot thedischarging Huid, presentingI a stat-ical pressure-torce between the clearance-space and discharge of the pump to shut ott the clearance-space against being overcome bv back-pressure from the discharge. In the particular means l have provided for my purpose, the pitch-angle ot' the spiral-shaped vanes is sutliciently tlat. to set. up this statical pressure lwithin the clearance-space without causing radial outward flow therein. That pitch, ot course, as will be understood, rshould be changed to adapt it to the physical condition ot the fluid to be pumped, meaning that 'for viscous liquids the pitch-angle should be flatter than for mobile liquids.

I realize that considerable variation is possible in the details of construction thus specifically shown and described, and i do not intend by illustrating a single, specilic or preferred torni to limit my invention thereto, my intention being in the following claims to claim protection upon all the novelty there may be in my improvement as broadly as the state of the art will permit. Thus, while the spiral torni of the counterpressure-producing means herein described is believed to best, serve my purpose, the purpose being to provide such couiiter-pressure, any other means on the outer 'faces of the annular shroud-walls that will etfectthe same result are within my invention.

1What l claim as ne i and desire to secure by Letters Patent, is

' l. ln a centi'itugal pump, an impeller adapted to prevent back-leakage of tluid through the clearance-space in the pump, comprising annular shroud-forming walls on opposite sides of the iiupeller-blades, provided on their outei' 'faces with means producing and maintaining, by the rotation of the impeller, statical. counter-pressure et [luid in the clearance-simce 'for resisting back-flow without producing aradial outward ttow through said space oit the tluid discharging t'i'ointhe pump.

2.1'11 a` centrifugal pump, an iinpeller provided with ineaA s tor preventing backlealiage oit Afluid through the clearance-space in the piunp, said'nieans con'iprising annular sliroud-torming walls on opposite sides ot the iinpeller-blades, having on their outer lfaces spiral runways constructed and `arranged to produce and ii'iaintain, by `the i'otation oit the in'ipeller, statical counter-pressure of tluid in the clearance-space toi' resistingback-How without` producing a radial outward flow through said space ot the l'luid discharging from the pump.

3. ln a centrifugal pump, the combination with the casing, ot. an iinpeller journaled therein, provided with means 'for preventing back-lealuige ol tluid through the clearance-space in the pump, said means comii'ising annular shroud-torniing walls on opposite sides ot' the iinpeller-blades ei:-

tendingl inwardly from the outer blade-extremities and having on their outer faces spiral run-ways extending from the inner edges ot said walls outwardly and in the direction opposite the direction ot rotation ot' the iinpeller to produce and maintain, by the rotation of the impeller, statical counterpressure o'l [luid in the clearance-space toi' resisting back-flow wit-hout producing a radial outward tlow through said space ot the fluid discharging troni the pump.

JOSEPH, SCHNEBLE.

ln presence oli# .loi-1N W son, Raisin-i' A. Sci-muren.

Copies of this patent may 'ne obtained forifive cents each, by addressing Ythe Commissioner of Batents,

Washington, D. C.

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