US2661698A - Centrifugal pump - Google Patents

Description

Dec. 8, 1953 c. A. SCHELLENS 2,661,698

\ CENTRIFUGAL PUMP Filed March 21, 1951 2 Sheets-Sheet l Dec. 8, 1953 c. A. SCHELLENS 2,661,598

CENTRIFUGAL PUMP Filed March 21, 1951 2 Sheets-Sheet 2 Patented Dec. 8, 1953 UNITED STATES PATENT OFFICE 12 Claims.

This invention relates to centrifugal pumps and more particularly to single stage centrifugal pumps employing one double inlet runner, such a pump being shown in my Patent No. 2,101,653, granted December 7, 1937. In order to provide for assembling such apparatus it is customary to divide the pump housing into two parts on a horizontal plane which contains the axis of the driving shaft of the runner, the two parts being secured together by bolts. It has been found diflicult to make the joint between the parts tight against leakage, particularly when high pressures are developed and when diffuser vanes are employed.

In high pressure pumps it is necessary that the clearance between runner inlets and the stationary wearing rings be made as small as possible to minimize leakage of pressurized liquid from the chamber containing the discharge portion of the runner to the suction chamber at the inlets of the runner. To this end, the bearings of the shaft on which the runner is mounted must be accurately centered with respect to the wearing rings, and it is extremely difiicult to 'securethis centering'with the split casing construction. An object of this invention is to provide structure for assembling anddisassembling the separable parts of the pump without disturbing the pipe joints which are secured to the casing to supply liquid to the pump suction and to conduct away the liquid discharged by the pump. For this purpose, the pump casing is made with a circular opening at one side which is concentric with the drive shaft and is of sufficient size to admit the removable parts which must be assembled within the casing to complete the pump. In assembling the pump, these parts are moved into the casing along the axis of the drive shaft, as hereinafter described, and a plate or head is secured to the casing to close the opening.

Another object of the invention is to provide a novel means for securing in place two diaphragms which are mounted with a diffuser within the casing to enclose the discharge portion of the runner or impeller in such a manner asto avoid or minimize leakage of pressurized liquid from the discharge end of the diffuser through the joints between the diaphragms and the casing. V

.,For a more complete understanding of the "invention, reference may be had to the following description thereof and to the drawing, of whichv Figure 1 isa sectional view of a single stage "centrifugal pump embodying the invention;

Figure 2 is a section on the line 22 of Figure 1, on a larger scale;

Figure 3 is an enlarged sectional view of a part'of the structure shown in Figure 1;

Figure 4 is a sectional view of a modified form of the invention shown in Figure 3; and

Figure 5 is a section on the line 55 of Figure 4.

The pump illustrated in Figure 1 comprises a casing l0 which is detachably secured to a main casing [2 by suitable means such as bolts [4. The main casing l2 may contain a prime mover (not shown) 'for the driving shaft l6 which projects through the casing II]. The pump casing shown on the drawing consists of three parts, namely, an outer casing member 20, an outboard head 22 and an inboard head 24. 'These three parts enclose a suction chamber 26 which communicates with the inlets of the runner or impeller 30 hereinafter described. The heads 22 and 24 close the circular openings in the casing member 20 which are concentric with the axis of the shaft IS, the opening which is closed by the outboard head 22 being of larger size than the diameter of the inboard head 24 and also of all of the other parts, hereinafter described, which must be inserted to assemble the complete pump. The head 22 contains a suitable ball bearing assembly 32 for the end of the shaft l6, this bearing being mounted in a suitable retainer or holder 33 having a cover 34 which protects the end of the shaft. The bearing 32 may serve as a steady bearing and as a thrust bearing for axially positioning the shaft and the rotating members relatively to the casing. A roller bearing 35 is provided for the portion of the shaft between the head 24 and the main casing I2. This bearing is mounted in a retainer or holder 36 which is secured to the casing l2 and is supplied with a cover 31 which clamps the outer race of the roller bearing 35. The heads 22 and 24 are provided with suitable soft packing 38 and 40 to prevent leakage from the suction chamber 26 along the shaft. The shaft has a splined portion 42 on which is slidably fitted the hub 44 of the impeller 36, the impeller being held in proper axial position on the shaft [6 by spacing elements on the shaft, including sleeves 45-and 46, which are gripped longitudinally between a nut 41 onthe outboard end of the shaft and a shoulder 48 on the shaft abutted by the inner race of the roller bearing 35.

Integral with the casing member 20 is a shell 50 which encircles the shaft and impellerand contains a volute discharge duct 52 to receive pressurized liquid from the impellein This duct communicates with a discharge pipe (not shown 3 which may be secured to a flange 54 on the easing member 20. Similarly a supply pipe (not shown) may be secured to a flange 56 on the casing member 20 so as to communicate with the suction inlet 58 of the pump casing. The shell 50 of the casing member 20 has a stepped bore therethrough which is coaxial with the shaft IS, the steps. forming shoulders 60; and Slwhiclrface towardithe outboardside'of the casing. Mounted within this bore are two diaphragms B4 and 66,

the outboard diaphragm 64 having a marginal p' area on its outer face or on a radial flange, 6,8, l.

which bears on the shoulder 60, the inboard 'diaphragm 66 having a marginalraiea on a radial flange 70' which bears on the shoulder 6 2 Gripped between the periphralportions of-the diaphragms is a diffuser which encircles-the dis charge ports 14 of the impeller and is preferably composed 2 of two separable annular parts 'lz and T4: the latter having a series ofQVa'nes TBQeXt ding. therefrom. to abut: the, part 1;. Their difii s r rid Passes ro h w a s e 84 h eh enemas; arb'undlth'ej 'di-fiiiser and communicates with the voluteduct .52. The liquid pressurejn th'fpassage, 841s much higher than in the sue.- tiorI chamber. 26[ Hence it is necessary that the joints between theoasin'g' memberwill and the diaphragms 64 and Blifbe. tight. Whenthepurnp ,is lop fatin'g, the pressure of the liquid in the clfiamixerv l1 s and the clearance 833 between the diffused and they inboard diaph'ragm B5 coperates withsl ficient force to: maintain. ,a. tight seal at th point the fliduid pressure in} the dis;- ch Q passage 8 4 which, communicates with a clearance '88 between the difiuseii and the, outl e TdadiapH einM e s db h h fianee 6.8

way from, thejshoulder' Q and thus to promote lea ag at 'thatpointt In order to ov r omcih means offrafscrew thread or equivalent in the effectsfof such liquid'pressure l mount a ringfly outb a n portion bfythe b e. ofthe casin member- .59 QaSQiiidicated at 192. The clearance .diameterofthis portion of the .bQreis sufiiqiently large to admit the :diaphragms ,and. .thedifiuser sac that t ey c n be inserted and asse bi q m the bore whenintroducedthrough theside open: v. pe mg ing normally closed by 'the head 22.

01i mi e t a e s .e q twn i rm s aeed r und desi edwe th e 9 9 e n adapted .to receiveca series oi bolts 9.;whi ch e ce tendvthrough the ring in the direction parallel to, the shaft is} After the diaphragm; and, dif serv ndim el er hav e ng sseliip das in i cated in Figure l, the ring is screwed into -p oe until it abuts the outboarddiaphragn fit; It then be slightly zbacl zedj off, whereupon-the indii d1 a bol sflp rs t in tQPE S-S IQQWeg i the .ou bo d ianh a m wa t q lisi e ss :fifithe ceq ier-a ains heshoelde fl th urin atishtioiptifvt iezne ztshavebeeaei fitted.

dif -us r also. 7 as a, flan e. 1 l 2 .a ts. oute p 1 e1 .htl1a ne a si ular enin thstandi- In operating high speed pumps it is necessary to make frequent inspections of the bearings and to renew them when necessary. Such inspections are facilitated by the fact that the diameters of the removable parts shown in Figure l are less than those of the openings through which they must pass to be assembled or disassembled, -'I;-hus theroller bearing 48; and its retainer 3E. and eover-3e1 can pass through the opening normally closed by the inboard head 24. The inboard head likewise can pass through the bore irrthe shell 50 when the diaphragms and diffuser have been removed, and all these parts, aswell asthering 90, can pass through the outboard opening in the casing l0. Furthermore, since the reller bearing 48 is mounted in a retainer, any scoring of the mounting due to accidentalseizure will be confined to the retainer wh ch. an easil e e laced he. mai cas rsmaie s mta t i I s de i ble hat, h an Q i lie in: a d i m, e. firmly el nst. t e shoulder BZl seas to, avoid leakage whether or not t e pum s de l in r u l s u eo this e d he fi s r rt v r a e w th la es i h P 793 s n pposi i ec ons e 7 a t "has afiange 95 at its inner perimetehthis ange bearing a t. th adieeent id oi th ou board, d a hr m 9; T e difiuser. a saflan e 12 uter, 1 E 38?? earin against the. nb a d dia hra m 61 nce we? flanges are radially offset; the thrust of the out oard, aphra m inst heflsn eflfi; ,wh h ansm t d h ough, he nes 5 and the l e e 98 to the, diaphragm 66 tends to distort the ser b spr n in rt rna ts l ght a isd is- 9 7 9 03 P TQV G p i fifi hi ss e diaphragm fiange'lfl against the shoulder :62 the imensi O he d us rt and he r' an being such as to result in such distortion of the difiuser when the, outboard diaphragm is clamped strongly against the shoulder 50':

In the case of veryhigh delivery pressures, a difiuser structure suchasis shown in- Figures 4 and' 5 may, be preferred, In this caset'he fi ser, Par ".9 and are r v ded with fla ge 1 $4 a d. e j-res t v at that meet er met heo ens 16' sceur t csfiai d to have, a radial force fit against -the' shoulder 0 t diap r B6 q Pr e i area while h eetase etwsen the flan e 194 an e. a hra m 5. ,me nts by. th iehtez a abutment. t een themhe a t flz qithe imam: hea ngegai is .th 'r aee i th dia hra r. 5 is aneelisnrovidced th.a. er btlraldialysl ts. I HQ e qalize the liquid nressure i ths=. 1ee tae9e .r e ween the part 1 H12 and ine iaphragm 66 withthe pressure in the passage -1, in e heinressuse wi in e h rffusers at al mim lesst n n-- herna ea e athemv Qr -inthe ex e nal d l aran soo e e iftuse pa ts. it g iqlrt e p ssa e 7 8 twi e:unisa es thef c Parts of ho ifi se retie bl -slamped agate bx n at s l uid pr ssu and me de igfnia ea the ifiuser arts. du to axia a e aute afianeeslfl and l i iec rthet ees sary tight contact at 62.

I claim;

a r ent ii eai numbaareasi s includ n threaded outboard portion and an inboard por:

tign, i sma lsn vi ti lr ,t ts m n. the router ni mie he l,.de ,betwen-.s idm t a cular diaphragm" closing said opening," said diaphragm having a marginal area fitting against ;said shoulder to form a joint normally washed by liquid pressurized by said pump, and means a, for pressing said area strongly against said shoulder to make the joint tight, said means consisting of a ring screw threaded in the outboard portion of said opening to abut the outer side .of said diaphragm, the clear diameter of the .threaded portion of the opening being greater than the diameter of the diaphragm, and a series of bolts threaded through said ring parallel to the axis thereof to bear against the outer side of said diaphragm, said bolts being, uniformly spaced around the circumference of said ring.

2. In a centrifugal pump, a casing including .-,.a member having a circular opening with two annular shoulders therein, the inboard shoulder being of lesser diameter than the outboard shoulder, two circular diaphragms in said opening bearing against said shoulders respectively to formjoints washed by liquid pressurized by said pump, a stifily resilient deformable member betweensaid diaphragms engaging the opposing faces of the diaphragms near the perimeter thereof, and means for pressing said diaphragms strongly against the respective shoulders to make said joints tight, said means consisting of a ring 1 outboard diaphragm is pressed strongly against its shoulder by said bolts, the member is deformed to press the' inboard diaphragm against its shoulder.

Apparatus of the class described comprising amain casing, a pump casing secured thereto, said pump casing having an opening in the outboard side thereof remote from said main casing, a head secured to said pump casing to close said opening, a shaft projecting from said main casing through said pump casing, an end of said shaft being journalled in said head, a doubleinlet impeller keyed on said shaft, said pump casing and head enclosing a suction chamber communicating with both inlets of said impeller, said pump casing having an inner portion enclosing a volute discharge duct and having a stepped bore coaxial with said shaft, two diaphragms mounted within said bore and pressing against the steps therein, a diffuser gripped by the said diaphragms in said bore and encircling the discharge ports of the impeller, and means for pressing said diaphragms against said steps, the opening in the outboard side of the pump casing being of larger diameter than the impeller, diffuser, diaphragms, and pressing means whereby said impeller, diffuser, diaphragms and pressing means can be introduced through said opening along the shaft to assemble the pump structure.

4. Apparatus as in claim 3, said pressing means consisting of a ring removably mounted in said bore next to the outboard diaphragm, and a series of bolts threaded through said ring parallel to the axis thereof and bearing against said outboard diaphragm, the portion of said bore in which the ring is mounted having a clear diameter greater than that of the diaphragms, diffuser and impeller.

.. V 5. Apparatusas in claim 3, said pump casing having an opening on its inboard side concentric with the shaft, an inboard head closing said opening, said inboard head being of smaller diameter than the outboard opening, whereby it can be introduced. into said casing throughsaid outboard O ening.

said shaft, an impeller keyed to said shaft within said inner shell, two spaced diaphragms fitted within saidinner shell and enclosing a chamber within which said impeller is rotatable, said inner shell having a stepped borewithin which saiddiaphragms are mounted and annular shoulders within the bore against which the diaphragms are pressed, a diffuser gripped between the peripheral portions of the diaphragms, and

means holding the difiuser and diaphragms, in

assembled relation, said means consisting of a ring threaded into a portion of said bore to abut, one of said diaphragmsan-d .a plurality of bolts. threaded through said 'ring and parallel to the shaft, axis to pressathe. adjacent diaphragm.

against one of said shoulders and against, said.

I diffuser.

7. A centrifugal pumpcomprising a casing a.

shaft extendingtherethrough and an impeller:

keyed on the shaftysaid casing consisting of am outer shell member having two opposed openings concentric with the shaft, two suction heads secured to said member to close said openings andi enclose with said member a suction chamber, each said head having a bearing for said shaft, an inner shell within andintegral with the outer shell member, said inner shell enclosing a volute discharge duct and having a stepped bore concentric with said shaft, two diaphragms mounted in said bore and spaced to form a chamber in which said impeller is rotatable, a diffuser gripped between said diaphragms and encircling said impeller, said diaphragms having annular shoulders bearing against steps in said bore, and means for holding the diaphragms and diffuser in assembled relation, said means consisting of a ring screw-threaded into said bore to abut one of said diaphragms, and a plurality of bolts threaded through said ring parallel to the shaft axis to bear against the adjacent diaphragm at spaced points.

8. In a centrifugal pump having a casing, a shaft extending through the casing and an impeller keyed to the shaft, said casing having a stepped bore coaxial with the shaft and of larger diameter than the impeller, two diaphragms mounted in said bore and spaced to form a chamber in which said impeller is rotatable, said diaphragms having eripheral shoulders bearing against steps in said bore, a diffuser gripped between the peripheral portions of said diaphragms, said diffuser consisting of two separable annular parts with vanes between, said vanes being attached to one part and bearing against theother, a flange on the inner periphery of one said part bearing against the adjacent diaphragm, a flange on the outer periphery of the other said part

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