US2366964A - Centrifugal pump - Google Patents

Description

Jan'. 9, 1945. G.' P. E. HOWARD 2,366,964

CENTRIFUGAL PUMP Filed May 5, 1942 3 Sheets-Sheet l Arme/wxs Y Jan. 9, 1945. c. P. E. HOWARD CNTRIFUGAL PUMP Filed Mays, 1942 3 sheets-sheet 2 Jn 9 1945- G, P. E. HOWARD 2,366,964

` CENTRIFUGAL PUMP v Filed May 5, 1942 5 Sheets-Sheet 3 01 [JLlll l l I l l I 14m GJ? How/ARD.

l Patented Jan. 9, 1.945

y 2,366,964 l CEN'rRIFUdArl PUMPl y Giles ,Philip Eliot Howard, Aniersliam',l lilngland Application Mayv 5, 1942, Serial No. 441,842 3 In Great` Britain Mayv"5,1941

izr'z'laims.v (arios-1.02)-

, y e I meansy may comprise'- juxtaposed sets `of, spiral This" invention vrelates centrifugalV pumps of the multi-stage" type.v

Pumps of this. kindjhave 'hitherto been built' upxofparts comprising, for each stage, asuc-y tion chamber defining member, an impeller membei'r andfguide meansioradirecting .the liquidv discharged rfron-ifthelirnpeller into the: suction. chamber of thenext-Ystage. "1n they case forr instance of ordinary-'- horizontal high lift` turbo pumps, eachvstager-comprlises a bowl having pas-1 j sages designed toconvert' thehigh' speed tan# gentialilow from, oneimpeller into .an axial flowat'y the;k entryv of` thei next impel1er,-the 'bowls' being"'connectedtogetherfin series; or alterna-- tively,` each stage.` comprises an impeller, afdiffuser member taking the radial and tangentiall ow- @and/converting it? into a tangential and axial iiow; and althirdguide member which convertsthis latteriflow 'into apurely axial; flowV at the eye ofthe next impelleri vThis arrangemenf--is e sometimes modiiiedso thatthe. diffuser -vanesl do not lchange the direction of@ i'lo'w'entirely to the axial but merely reduce the tangential .velocity and in this caseV anA outer chamber o fv semiy toroidal form is` provided; to redirect the. iiow intovthemeturn.guides which'4 convert the flowA .Lz-

into anv axial iowl at fthefi eye ofthe; next im peller. i

f Inl all such forms of construction yexternal meansv have tof bei provided; for; assembling; ,the stationaryr or,v guidev members-noi the successive i stages in:end-toendrelationship, and fory this purpose, there: are usuallyy employed yeither i an enveloping` :tubular member with compression means atl the ends or long bolts passing outside s or throughgholes in the-.guide members or studs and nuts-.laia-:each1 stage.to bolt it to the next.' In every-fv case, such securing meansentail a substantialfincrease in the outside diametervof the'` pump, and-anyoutside. casingv provided is extraneous. `Vto the essential componentl parts of thepump. f s

lIl'x-is general mode ofl constructionA is; dictated by the assillned: desirability of"v suppressing turbulence by"` curving.y the outer wall' o-f. tiles-guideA means; :by which the liquidflow is diverted between the point of, leaving an impeller .of one stage and enteringjthe, suction chamberl of the nextstage.v

.I- havey foundtliaffgl ,givenl suitable arrangef ment` and dimensioning ofthe. guide means, this assumed;` requirement may beA dispensed ,with, andl that the divertingi peripheraly .surface of thei guide. means, may benormal to tharadial planes. of..v .thek pump assembly,y wthoutjappiieficialrle loss .of-ediciency.. Consequently the guide or inclinedfvanesmounted in afperipherally open annular'supporting-structure and` adalfxtedv tofguide the discharging andente'ringl` nows tangentially, while thefdiversion therebetween is effected by' a cylindrical/wall suitably 'spaced from said sets of vanes.

From "this it follows lthatv theL provision ofl an independent" housing canr ber dispensedr with' and the required lcylindrical lWall may be formed" n theA housing itself which thus particilzaatesjinv the liquid guidingfunction. A y

The invention accordinglyjconsists in a multistage centrifugal pump fwherei'n the. external housing itself forms part-'ofl the meansfor guid ing the ilow -betweenfsuccessivestages.

In lfurther development ofthe invention, the stationaryparts of- 'they pumpvv areA formed with cylindrical peripheral surfaces of thersamediameter and theexternal housing consists of; -a single cylindrical member' kadapted 'tol be simply 'ttedslidinglyover the consecutively assembled partsloffthe'pump, to 'complete the assembly;

It will be appreciatedrthat in1thisway, a ver-y reat simplification.` of the work of assembly and dismantling is achieved, as compared with pumps havingi an'l extraneous sectional housing, quite apart fromv the fact'that'fthe construction orf the individual parts is greatly simplified and the Ytotal amount of machining required is very materially 1 reduced.V LOwing-,tothe use of acne-piece cylinto besubstantially, reduced without sacriceof strength. -Moreover, owing to the economy in diametrical dimensions-,achieved by the invention,A the .furtheradvantage is obtained, that impellers of larger y,diameter mayfbezL-used, re-

Esulting in a greater pressure gain per stage and enabling fewer stages to be used in a pump oi :given .over-all diameter, with fewer parts. and a-shorter shaft. g

InV order that the inventionmay be `moreyfully comprehended. andY readily carried into. pracftice, an embodimentfor its various featuresis illustrated, by` way of ,example only, inthe accompanying drawings, in which:`

Figure 1 shows, inlongitudinal section, a completepump` according Vto Vthe invention, with a combined iiuid admission and motor attachment piecev tted .to the4 inlet end thereof;

Figures l2, andy` 3show in axialsection yand in elevation respectively, one of the impellers of thelpump; l

Figures 4 andv 5 are viewsralso invaxial section and in elevation respectively of an interstage guide Vane member;

Figures 6 and '7 are respectively an axial sectional view and an elevation ofthe end bearing member or cap of the pump rotor;

Figures 8 and 9 are like views of the balance disc;

Figures 10 and 11 `are like views of the balance seat; and

Figures 12 and 13 are like views of a diffuser member operative on the fluid on discharge from an impeller,

As shown in'Figure 1 the pump is of multi stage type with three conventional stages, and the pump is terminated at one end by a fluid admission rpiece I through which the pumped liquid is admitted to the first stage of the pump proper. The said fluid admission piece l is constru-cted, in accordance with the invention forming the subject; matter or British application No. 5820/41 led May 5, 1941, with a cavity 2 which houses the couplings between the pump shaft 4 and the shaft of the driving motor,

which is not shown, but is bolted to the end flange of the admission piece.

'I'he cavity 2 is formed by a conical wall or socket 6, the forward end of which is bored to form a seating 1a to receive the bearing sleeve 1 for the shaft 4, the bearing being cooled by con duction to the wall ,E and seating 1a andA by the' pumped liquid which sweeps over the outsides of the seating 1a and wall 6. The heat of the `top motor bearing and the end turns of the motor winding is also transmitted to the wall 6 by the liquid contained in the cavity 2 and maintained in a state of turbulence and circulation by the rotating coupling 3. Liquid for lubrication of the pump bearing can pass along the bearing clearance from cavity 2, and the end of the bearing is protected` against the entrance of sand or the like into the bearing by the sand bell 8, which has a number of openings 9 to allow adjustment of the pump shaft by means of a tommy bar applied through one of the inlet orifices of the admission piece I. The admission piece I is surrounded by a gauze or perforated screen |0 to prevent the entry of solid matter into the pump through the inlet orifices and'passages of the admission piece.

On the pump shaft 4 are successively assembled the distance sleeve 4a, the sand bell 8, and the three impellers II each of which comprises an elongated or sleeve-like hub I2 carrying the impeller wheel proper formed by a solid wall or flange I3 and an annular Wall I4 which leaves an opening round the hub sleeve AI2 to form an annular inlet eye I5. Between the Walls I3 and I4 are disposed vanes I6 suitably designed to produce the desired flow of the liquid through the impeller.

Between the impellers are disposed stationary return guide vane members I1, carrying wearing rings I8 of the kind forming the subject matter of British Letters Patent No. 539,373. The return guide vane members I1, comprise a disc wall |1 of less diameter than the end ring of the admission piece I, having a short hub I9 fitting on the subsequent impeller hub sleeve I2, guide vanes 20, and an annular wall 2| of the same diameter as the end ring of the admission piece l, Whose internal periphery forms a throat 22 opening into the eye of the next impeller II.

The wearing ring I8 is carried by the annular wall 2| and makes running contact with a shoulder ring on the internal periphery of the annular wall I4 of the adjacent impeller II, and between the periphery of the disc Walls I1 of the return guide vane members I1, and the wearing rings I8 of the preceding guide vane member I1 are clamped diffuser members comprising suitably curved vanes 23, surrounding the impeller II, projecting laterally from annular plates or rings 24 (Figures 12 andlS) Packing rings 33 are disposed between the diffuser rings 24 and the peripheries of the'annular walls 2| of the return guide vane members I1. The vanes 23 do not extend as far as the periphery of the ring 24, which corresponds in diameter to the rings 2l and the end ring of the admission piece I, so that an annular space surrounds the vanes 23 which is bounded by the outer casing of the pump, the surface of which thus participates in the guidance of the water flow between stages..

Above the final stage `impeller I l and abutting against the vanes 23 of the last diffuser member, is disposed an annular balance seat 25 carrying a balance ring 23, which makes contact with a wearing ring 21 carried by a balance disc 23 mounted on the shaft 4. The balance disc 28 has an elongated sleeve 48 keyed on shaft 4. The parts keyed to shaft 4 viz: distance sleeve 4a., sand bell 8, impeller hub sleeves I2, and balance disc hub sleeve 43, are axially clamped on shaft 4 by the end nut 29, and finally the sleeve 43 on shaft 4 is fitted into the end cap 38, which contains the topV bearing sleeve 49, held in bearing shell 50, and in its cavity accommodates the balance disc 28. The end cap 30 is formed integral with the upper end member or delivery piece 3| of the pump, being connected thereto by webs 44 so as to form delivery channels sweeping overr the outer surface of the cap 39, and communicating on the one hand with the discharge opening 32 of the pump and with the annular peripheral space surrounding the diffuser 23, 24 encircling the last impeller I I on the other hand.

Surrounding the delivery piece 3| is a bolster ring 34 with an interposed packing ring 35, and the whole of the parts assembled on the shaft 4, including not only those keyed to the shaft, but also the interposed annular members, viz: balance seat l25, impellers II, diffuser members 23, 24, and return vane members I1 with their wearing rings I8, are inserted, as a cylindrical block, into a plain cylindrical casing 36, which tsv on, and is fastened to the periphery of the end ring of the admission piece I by grub screws 31. The annular interposed members of the pump as sembly are then tightened up by means of thrust bolts 38 threaded in a counter `supporting ring 39 inserted in the discharge end of casing 35 and secured by grub screws 42|.` Finally a flanged ring 4| carrying the delivery pipe 42 is secured over the delivery piece 3| of the pump by means of the nuts 43 on bolts 38. y

From the foregoing description'it will be appreciated that when the bolster ring 34 is tightened up by the thrust bolts 38, the delivery piece 3|, and end cap 38, together with the diffuser members 23, 24, wearing plates I8, return vane members I1, and admission piece I, form a solid cylindrical assembly presenting a smooth cylindrical outer wall fitting ywithin the cylindrical outer casing 35. Dismantling is effected simply by reversing the assembly operations.

It will be understood that the spaces formed between 4the inner Wall of the casing member 35 and the outer edges of the vanes 23 and the annular plates 24 of the diffuser members constitute of the, guide vanas `A23V `detriment-al' turbulence inthese chambers-is avoided:

The invention thus provides a centrifugal pump with a one-piece outer casing which serves the dual purposes of guiding the pumped liquid 4from a set of diffuser vanes to a set of return vanes and of acting as the main locating means for the pump assembly. It also provides a pump which is simple and robustr in construction, of light weight and requiring a minimum of machining, and which is capable of being assembled and dismantled with exceptional ease and rapidity.

What I claim and desire to secure by Letters Patent is: Y

1. A multi-stage, radial flow centrifugal pump comprising a plurality of bladed impellers arranged in coaxial stages and respectively cooperating with adjacent bladed guide members for controlling the ow between stages, in combination with a one-piece casing surrounding the impellers and guide members in radially spaced relation thereto and providing a cylindrical sur- -face defining within the same circumferential channels outwardly of the guide 'members for guiding the flow from an impeller into the adjacent guide member as thepumped uid passes from one impeller to the next.

2. A multi-stage, radial flow centrifugal pump comprising a plurality of impellers arranged in stages in coaxial relation, and associated guide members for controlling the flow of liquid beripheryA yofi-the final impellernchamber, .andfa bearing for onewendof thepum-p shaft ,supportedv by the-bearingfshell.

16. A- .pumpas'deiinedin claim 3.,'wl1ereinA the set' of diffuser vanes: has an` annular form, with? v.the variesv disposed about `the' periphery -of* the; impeller 15o-guide the liquidin a radially -outwardf direction, and the cylindrical wall of the outer external one-piece cylindrical casing circumfertween said stages, said impellers and guide memf bers being threaded in succession upon a central shaft and enclosed by a one-piece cylindrical casing, and the guide members including means for directing the flow in directions both radially and outwardly and radially inwardly in succes'- sionbetween the impellers of successive stages.

3. A centrifugal pump comprising a rotary bladed impeller to produce radially outwardl flow respecting the axis of rotation, a set of stationary diffuser vanes adjacent to the impeller and in the path of radial flow from the latter, a set of stationary radially inward flow return vanes also associated with said impeller and diffuser vanes in axially spaced yrelation thereto and coaxial therewith, and a one-piece cylindrical casing en nels leading to a central opening registering with the eye of the first impeller, a bearing shell disposed in said end member in such manner thatA the outside of the 'bearing shell is sweptby thev fluid passing along said channels, and a bearing for one end of the pump shaft, mounted in said bearing shell. y

5. A centrifugal pump as defined in claim 2,

' including an end member in one end of thecasing provided with an axial uid discharge open-y ing, a bearing shell disposed in said end member so that its outside wan is swept by the fluid passing to said discharge opening fromfthe peentially spaced from the impellers, and into which the vcylindrical shaft assembly is axially inserted and fastened at its ends, and means for axially clamping the intermediate annular fluid-guiding partsV to hold the same stationary while leaving the impellers free to rotate relative thereto.

8. A centrifugal pump as denedin claim 2, in

combination with an end member disposed at one endof the casing and provided with fluid inlet orifices and channels leading to a central opening registering with the eye of the rst impeller, said end member serving not only as an admission piece for the pumped fluid, but also as a connecting piece between the pump and motor casings.

9. A multi-stage, radial ow centrifugal pump including, in combination, a plurality of radially outwardly discharging impeller members arranged in consecutive stages on a common axis, radially outwardly directing and radially inwardly directing bladed guide members between consecutive stages, and an outer one-piece cylindrical casing radially outwardly spaced from the impellers and .providing an interior cylindrical surface for converting the radially outward flow of the fiuid from an impeller and its associated outwardly directing guide member into the adjacent inwardly directing guide member.

10. A multi-stage, radial flow centrifugal pump including, in combination,A a shaft, a plurality 5 of impeller members mounted in succession on said shaft, a plurality of stationary radially outwardly and inwardly directing guide vane 111cm-,

back-to-back abutting relation to eachother between each pair of impeller members, and a casing enclosing the impeller members and vane members and providing cylindrical fluid-guiding surfaces concentric with the pump shaft between said diiiuser and 'return vane members to direct the liquid flow from the diffuser vane members to the return vane members .consecutively be tween the impeller stages.

12. A multi-stage, radial oW centrifugal pump including, in combination, a shaft, a plurality of impeller members mounted in succession on said shaft, a plurality of annular return vane members respectively located between said impeller members, hubs on said impeller members located in and by said annular return vane members, an-

nular diffuser vane members also respectively located between said impeller members and displaced axially from said return vane members in abutting relation thereto, and a, one-piece cylindrical casing fitting the external peripheries of said diiuser and return vane members.

GILES P. E. HOWARD.

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