US2331299A - Centrifugal pump - Google Patents

Description

Oct. 12, 1943.v y c. BLOM CENTMFUGAL PUMP Filed June 13, 1941 4 Sheets-Sheet 1 x E MR, M LO 0 5m n LE V mm mm, N .KN N fw in mm m 1 m.. wm NIHHHHMMWHMHMHHIHNIIHMH bv Muhlldllllllmnlwh mm@ Nw d@ .S R Q. a, wv QN H n@ m| Q s@ wz. v Nw w QN QN @an .mm m l- E S. mm mm E E Nm Q 7 a H .V A| N Oet. 12, 1943, c. BLOM I GENTRIFUGAL PUMP Fi1ed Ju'ne 15, 1941 4 Sheets-Sheet 2 n Mm M T m 5m r V @m M mm My nm.. im

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n M U 7 T A Patented'oa. 12, 1943 CENTRIFUGAL PUMP Carl Blom, San Marino, Calif., assignor to Byron Jackson Co., Huntington Parkgcalif., a corporation of Delaware Application June 13, 1941, Serial No. 397,836

2 Claims.

This invention relates generally to centrifugal pumps, and particularly to medium-pressure single case pumps of the type usually employed for pumping various classes of liquids in industrial processes'.

A principal object of the invention is to simplify the construction of a pump of the foregoing type in order to reduce the cost of manufacture and to facilitate dismantling and re-assembly of the pump at the installation point.

A further object is to provide a pump of the foregoing type which is particularly adapted to handle liquids atl high temperature. It is of ut'- most importance that adequate provision be made in pumps intended for this service to insure against differential expansion between parts at those critical points where surfaces contact to maintain centering or alignment between separable parts of the pump. Otherwise the centering o r aligning surfaces may separate as the result of differential expansion, and may result in objectionable vibration of the inadequately supported part. It is an objectfof this invention to prevent such differential expansion by subjecting all mating portions of the pump to corresponding heating or cooling inuences.

l A still further object of the invention isV` to provide an improved impeller shaft bearing assemblyl which, in conjunction with the novel estals I2 or other suitable supporting means. It will be observed that the opposite ends of the casing are provided with identical annular bolting flanges I3 and I4. A stufilngbox bracket I5 ls secured to the flange I3, and an end cover I6 is similarly secured to the opposite flange I4 to complete the enclosure of the impeller spaces in the casing. A bearing bracket I1 is bolted or otherwise secured to the outer face of the stuffingbox bracket I5, and, if desired, may be additionally supported on the pump base by an auxiliary pedestal II detachably secured to the bracket and to the base. The bracket I'I serves to rotatably support an impeller shaft I8 extending4 through thetwo brackets I1 and I5 and into the casing I0. A pair of impellers I9 and 20 are keyed to the inner end of the shaft, and are secured thereon by a nut 2I` threaded on the'end of the shaft.

Attention is directed particularly to the novel arrangement of fluid passages in the pump casing I 0, which greatly simplifies the assembly and dismantling of the pump. It will be observed that the suction eyes of the impellers I9 and 20 face each other, thus disposing the corresponding suction passages in the casing in the central portion thereof between the impellers. A suction inlet passage 23 extends from the suction nozzle 24 todischarging into a pair of diametrically opposed Fig. 1 is a longitudinal vertical sectional view l view having a pump casing I0. The casing III is preferably an integral casting having laterally extending bolting flanges I'I for attachment to pcdvolute passages in the pump casing. In this manner the radially acting hydraulic thrusts are balanced, and the impeller shaft is relieved of the bending stress which would otherwise be imposed thereon if a single volute were provided. Referring particularly to Fig. 4, diametrically opposed volute passages 30 and 3| are formed in the pump casing in the radial plane of the first-'stage im- 'peller I9. 'I'hese passages are connected to the' second-stage-inlet- 25 by individual cross-overy passages 32 and 33 (Fig. 2) extending from the respective volute passages 30 and 3| in a generally axial direction on opposite 'sides ofthe suction inlet passage 23. After passing the inlet^passage 23, the cross-overs 32 and 33 are curved yradially inwardly and merge into the second-stage inletv 25. It will be observed from Figs. 2 and 4 that the suction inlet passage 23 is necessarily of veryv Substantial Width ina radial direction, and the nozzle 38.

Referring once more to Figs. 1 and 2, the shaft opening through the stuflingbox bracket I is sealed by a packing gland 4I of usual construction. In order to prevent undue heating of the packing when the pump is used to pump hot liquids, the stufilngbox is surrounded by a cooling jacket l2 -to permit circulation of water or other cooling medium between an inlet (not shown) and an outlet I2. As is customary, provision is also made for circulation of water through the stuiilngbox from an inlet connection Il to alantern ring Il and thencebetween the packing Il ing follower.

It will be noted that the pump casing Il is provided with a cylindrical centering surface 50 adjacent the -bolting flange i3, and that the stuffingbox bracket Il is provided with a corresponding centeringsurface 5I adapted to have a close sliding n t in the centering surface 50 to .insure axial augment of the bracket with the pump casing. It is essential that these surfaces III and il be maintained in contact with each other in order to avoid vibration of the-bracket. It has been found, however, that these surfaces and 62 a completely closed bearing housing, and an outer wall 63 spaced from the wall 80 to form therewith a cooling jacket 84. Cooling liquid is circulated through the jacket between an inlet G5 and anoutlet 66. A deilector ring 6i* is secured to the shaft adjacent the end cover 6I to prevent cooling liquid issuing from the stuffingbox from entering the bearing housing.

,f 2 and a shaft sleeve 4l to an outlet 41 in the pack- 5 frequently become separated as the result of differential expansion between the casing and the bracket when pumping hot liquid. The pump casing, being exposed to the hot pump liquid, may be heated to a higher temperature than the stuifingbox bracket, inasmuch as the latter is subjected to the cooling influence of the cooling water in the jacket 42.

In order to avoidseparation of the centering surfaces il and 5I, I have provided an arrangement whereby the portion of the stuflingbox bracket II in the region of the centering surface Il is subjected to the heating influence of the pump liquid. to thereby cause it to expand or contract with the pump-casing. To this end, the inner radially extending wall of the bracket Il is recessed into the water Jacket l2, as indicated at 55, to provide an annular pocket ,or channel it which contains pump liquid when the pump is in operation. The annular flange I1 thus formed between the pocket 5I and the centering surface Il is thereby isolated from the cooling effect of the cooling liquid in the Jacket I2 and is exposed'directly to the pump liquid, and

will be heated to approximately the same tem- Derature as the portion of the casing I0 on which the centering surface 5I is formed. In this manner, differential expansion between the pump casing and the bracket in the region of the centering surfaces l0 and Il is avoided, and vibration of the bracket resultingfrom separation of the surfaces III and 5I is consequently eliminated. Referring now to the bearing bracket'll and the mounting of the impeller shaft I8 therein,

' it will be observed with reference to Figs. 1 to 3 that the bracket comprises an inner circumferential wall BI! forming with the end covers 6| The shaft I8 is journaled in the bracket l1 in spaced bearings 61 and 6B, preferably of the ball bearing type. The bearing V6l assumes only radial thrust, being mounted for limited sliding movement in the bearing seat 69 in the bracket. The bearing 68 assumes not only radial load but also any axial hydraulicV thrust imposed on the shaft by the impellers. To this end, the outer race of the bearing 68 is provided with a circumferential groove containing a split retaining ring 'ID adapted to be clamped between the end wall of the bracket and the end cover 62, The inner race of the bearingt is secured to the shaft between a shoulder on the shaft and a nut threaded thereon. This construction has the advantage of permitting the use of a standard bearing without requiring a counterbore in the bracket to form a seating shoulder for the outer race. The bore 1i in the bracket is only slightly larger than the inner bearing il, to permit the latter to be inserted freely therethrough during assembly.

I have provided a novel and improved system of lubrication of the bearings 61 and 68. The housing formed by the walls 60, 6| and 62 constitutes a lubricant reservoir having a filling opening 15 through the uppervwall and a drain port 16 in the sump formed in the lower portion. A supply, of lubricant is maintained at approximately the level indicated at 11. An oil iiinglng disk 18 is secured vto the shaft approximately midway between'the bearings. as by a set screw 19, and it will be noted that the flanges of the disk extend below` the level of the lubricant. During rotation of the shaft, the lubricant adhering to the submerged portion of the disk anges is carried upwardly and flung outwardly by centrifugal force against the wall of the housing.

In order to collect the lubricant flung from the disk and to direct it to each bearing, a channel (Fig. 3) is formed on the inner wall of the housing. As shown most clearly in Fig. 1, the channel slopes downwardly in opposite directions from the central radial plane Aof the disk 1l. Ports 8| and 82 extend through the end walls of f the bracket in registry with the respective ends 'of the channel 80, to direct the lubricant. from the channel to chambers I2 and 84 between the outer sides of the bearingsand the end covers 8| and B2. From these chambers the lubricant flows through the bearings and returns to the reservoir. A continuous circulation of oil through the bearings is thus provided. On the radially opposite side of the housing and approximately at the same elevation as the ports 8l and 82, a pair of overflow ports and 88 extend through the end walls of the housing to allow any excess lubricant to by-pass the bearings and thus control the levelof the lubricant in the chambers 83 and 84. v

The oil-ilinging disk 1I is superior in several respects to the conventional oil rings now in common use. A ring loosely mounted on the shaft is not positively rotated by the shaft, and fre-, quently such rings -become worn in one 'spot and fail to rotate. The disk 18, however, is rigidly secured to the shaft and hence affords a positive means for throwing oil onto the housing where it drains into the channel 80. It will be noted that the disk 18 is slightly smaller than the bore 1I in the outer end wall of the housing, to permit insertion of the ring when mounted on the shaft.

From the foregoing description, it will be apparent that I have provided a pump which is exceedingly simple to assemble and dismantle, and which will provide trouble-free operation over a long period of time irrespective `of the temperature of the liquid being pumped. The manner of assembly is believed to be obvious. It is desired to call attention, however, to the ease of dismantling to permit inspection of the rotating parts andthe interior of the pump casing. Upon removal of the end cover I6, the impeller nut 2| is removed from the shaft, permitting the removal of the second stage impeller 20. After the stuiiingbox bracket I5 has been unbolted from the flange I3 on the pump casing and the detachable pedestal I1a has been removed, the entire unit comprising the stufiingbox bracket I5, bearing bracket I1, and the shaft I8 with the impeller I9 thereon may be withdrawn .bodily to the right, thus affording access to the interior of the pump casing and permitting inspection of the impellers. It will be noted that inasmuch as the suction and discharge connections form a part of the pump casing, vit is not necessary to disturb those connections in order to dismantle the pump.

If it is desired to inspect the bearings 61 and 68, ths'may be accomplished with only slight additional dismantling. 'I'he impeller I9 is removed from the left end of the shaft, the end cover 62 is unbolted from the bearing bracket |1, and the deiiector ring 6 Il1 is loosened, and thereafter the shaft I8, bearings 61 and 68, and oil-fiinger ring 18 may be withdrawn to the right as a unit, leaving the brackets I5 and I1, packing gland 4I, and shaft sleeve 41 intact. Separation of the bearing bracket from the stuiiingbox bracket is, of course, necessary in order to4 renew the packing 4I. It

will be apparent from the foregoing that the however, to completely dismantle the pump in order to inspect and/or renew a single part.

Referring now to the form of the invention shown in Fig. 6, it will be observed that this form embodies many features and parts found in the pump'which has been previously described. The principal distinction between the two ernbodiments lies in the fact that the pump shown in Figs. 1 to 5 is of the overhang type wherein the shaft and impellers are supported only at one side of the pump casing, whereas in Fig. 6 the shaft is supported in bearings at opposite ends of the pump casing.

The pump casing I I of Fig. 6 is of identical construction with the casing I0 of Figs. 1 to 5, thus providing interchangeability of parts.` The 'stungbox brackets III and ||2, detachably secured to opposite ends of the pump casing, are also identical with each other and with the bracket I5 of Figs. 1 to 5. This is rendered possible by providing identical bolting flanges at opposite ends of the coupling, permitting the selective attachment of either two identical brackets as in Fig. 6 or of a bracket I5 and an end cover I6 as in Fig. 1.

Bearing 'brackets I|5 and IIB of identical construction are detachably secured vto the outer ends of the respective stufllngbox brackets |I| and H2, and each houses and supports a shaft bearing. The bearing II1 in the bracket |I5 is of the plain sleeve`type and assumes only radial load from the shaft IIB, whereas the bearing ||8 in the bracket |I6 assumes` radial load and also absorbs any axial hydraulic thrust imposed on the shaft by the impellers. 'The latter bearing is shown as a conventional stacked ball bearing.

It will be observed that the arrangement of the impellers with their suction eyes facing each other is the same in Fig. 6 as in Fig. 1, since the pump casings are identical. It will also be observed that the brackets III and II2 are provided with annular pockets or channels |20 and I2I to provide annular anges |22 and |23 which are isolated from the cooling effect of the stufngbox cooling water and are exposed to the pump. liquid lling the pockets I 20 and IZI, to assure uniform expansion of the flanges with the adjacent portions of the pump casing when pumping hot liquid. Separation of the cilin= drical centering surfaces |24 and |24' on the casing from the corresponding entering surfaces |25 and |25 on the brackets, and the consequent vibration of the brackets, are thereby avoided.

The assembly and dismantling of this pump is slightly more complicated than is the case with the pump of Figs. 1 to 5, but nevertheless involves a minimum of operations for this type of pump. In order to gain access to the impellers and to the interior of the pump casing, the bracket |II is disconnected from the iiange on the casing and is withdrawn bodily to the right with the bearing bracket |I5 4and its bearing H1. The shaft sleeve |30 and the rst stage impeller I3I are then removed to the right, leaving the`shaft free to be withdrawn to the left with the impeller |32 and the brackets |I2' and IIE.

It will beappreciated that certain aspects of the invention are equally applicable to other types of centrifugal pumps than the two which have been illustrated and described. For ex'- ample, the novel construction whereby separation of the mating centering surfaces on the casing and the bracket is avoided, is equally applicable to other than two-stage. pumps. The improved bearing construction and bearing lubrication system may also be used in conjunction with other types of pumps than those described. It will therefore be understood that the invention is not limited to the detailed construction shown in the accompanying drawings, but is of the full scope of the appended claims.

I claim:

1. In a multistage centrifugal pump, a unitary, circumferentially continuous pump casing having a removable closure at each end thereof and having a pair of axially spaced impeller cavities therein, an impeller shaft mounted in said casing, rst and second stage impellers o'n said shaft and rotatable in said cavities and disposed with their suction eyes facing each other, said casing having a pair of juxtaposed inlet chambers located between the impeller cavities and communicating respectively with the suction eyes of the impellers, said casing having a partition separating said inlet chambers, said partition being formed integral with the casing and extending inwardly into close proximity to said shaft, a suction inlet passage in said casing communicating with the inlet` chamber of the first stage impeller, a pair of discharge volutes in said casing arranged on 2. A multistage centrifugal pump as set forth in claim 1 in which a vcommon plane extending centrally through the axially extending portions o'f said cross-overs is substantially at right angles 5 to the axis of said suction inlet passage.

' CARL Brom.

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