US3779668A

US3779668A - Stage for a centrifugal pump

Info

Publication number: US3779668A
Application number: US00252355A
Authority: US
Inventors: W Ekey
Original assignee: McNeil Corp
Current assignee: McNeil Corp; McNeil Ohio Corp
Priority date: 1972-05-11
Filing date: 1972-05-11
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18
Also published as: CA978421A

Abstract

Disclosed is an improved stage adaptable for use in multistage centrifugal pumps which find their primary use in moving liquids from deep wells and the like. The pump can include a motor, rotatable drive shaft, external casing and at least one of the improved stages, each stage having an impeller to impart velocity to the liquid and a diffuser to reduce velocity and increase the pressure to force the liquid to the successive stages and to the pump outlet. The impeller is rotated within a stage housing, nonrotatably mounted within the pump casing, and includes a front and rear plate having vanes therebetween which spiral outwardly from the center to the outer edge of the front plate. The front plate extends radially outwardly of the rear plate and terminates in an axially directed flange having a diameter approximating that of the stage housing but clearanced to rotate therein. Liquid thus exits the impeller axially and is received by the overlying diffuser with a minimum of turbulence.

Description

United States Patent 1191 Ekey Dec. 18, 1973 STAGE FOR A CENTRIFUGAL PUMP 1.281.625 I2/196l France 415/199 A [75] Inventor. William J. Ekey, Jeromesvrlle, OhIO Primary Examiner c' J- Husar [73] Assignee: McNeil Corporation, Akron, Ohio Alt0rneyHamilton, Renner & Kenner [22] Filed. May 11, I972 S CT [21] P 252,355 Disclosed is an improved stage adaptable for use in multistage centrifugal pumps which find their primary [52] US. Cl 415/199, 415/141, 415/213, use in ng liquids from deep wells and the like. 415/501, 416/189 The pump can include a motor, rotatable drive shaft, 51 Int. Cl. F03b 1/04 external casing and at least one of the improved [58] Field of Search 415/199 A, 141, 213, g each Stage having an impeller to impart veloc- 415/501; 416/189 ity to the liquid and a diffuser to reduce velocity and increase the pressure to force the liquid to the succes- [56] References Cit d sive stages and to the pump outlet. The impeller is ro- UNITED STATES PATENTS tated within a stage housing, nonrotatably mounted 3 I 16 696 M964 Deters HS/Ml within the pump casing, and includes a front and rear ]584O [M963 i: 5/199 A plate having vanes therebetween which spiral out- 2 927:536 3/1960 Rhoades HS/l4] wardly from the center to the outer edge of the front 2978339 4/ [9m Lung n 415,199 A plate. The front plate extends radially outwardly of the 3,265,001 8/1966 Deters i 415/501 rear Plate and terminates in an axially directed flange 3,477,384 11/1969 Hlinka 4l5/I99A having a diameter approximating that of the stage 3,487,784 1/1970 Rafferty et al.... 415/199 A housing but clearanced to rotate therein. Liquid thus 3,6|2,7l6 l0/l97l DIYS 4l5/l99 A exits the impeller axially and is received the verly- FOREIGN PATENTS OR APPLICATIONS 9/1928 Great Britain 415/199 A ing diffuser with a minimum of turbulence.

10 Claims, 4 Drawing Figures PATEN'IEHBH: 18 am SHEET 1 u; 2

SHEET 20F 2 PMENVEH nu: 1 am The present invention relates to an improved impeller and diffuser design for a multistage centrifugal pump suitable for moving liquids from wells of various depths. Since the wells encountered may be quite deep, it is necessary to employ a pump capable of developing great pressure in order to force the liquid to the surface. Of the several factors which control the amount of liquid output, one which is necessarily limiting is the relatively small diameter of the bore through which must pass the entire pump including external casing, motor, and the many stages which actually contact and move the liquid. What the pump lacks in diameter is compensated by its great length and hence it is not uncommon to stack numerous stages within a casing to attain a lift of several thousand feet.

A single stage commonly includes an impeller, which is driven by the motor, to impart velocity to the liquid and an overlying stationary diffuser which decreases the velocity whereby pressure is increased causing the liquid to flow to the impeller of the subsequent stage. While the prior art is replete with multistage centrifugal pumps, the improvements have generally been directed toward increasing the life of the moving parts such as by dissipating hydraulic thrust or by providing engaging surfaces with abrasive resistant or retardant materials. While not without merit, inventors have concentrated more on these improvements and have not as frequently improved upon the design of the impeller and diffuser.

Heretofore, impellers have been constructed with a central hub adapted to be rotated by the drive shaft of a motor. The impellers have a front and rear plate centered around the hub with a series of spiral vanes therebetween to swirl the water generally radially from the impeller. An aperture in the front plate, concentric with the hub, provides the ingress for the liquid while the rear plate extends to the hub. The vanes drive the liquid radially outwardly where it is expelled from between the two plates with a high velocity.

The diffuser has also a front and a rear plate with a series of spiral vanes therebetween. A central bore therethrough receives the hub of the impeller which permits the latter to be rotatably driven by the drive shaft while the diffuser remains stationary. As the liquid exits from the impeller it contacts the stage housing and makes an approximate 90 turn therein into passages formed between the periphery of the front plate of the diffuser and the housing. The liquid is then guided by vanes within the diffuser to an aperture in the rear plate, which aperture is concentric with and of a diameter greater than the bore in the front plate and serves as the egress for the liquid to the impeller of another stage or out of the system.

The efficiency of such conventional items is somewhat undesirable in that the necessary 90 turn of the fluid radially out of the impeller and axially into the diffuser is accomplished in the diffuser or in an area between the impeller and diffuser because the conventional impeller of the prior art has been of a lesser diameter than the diffuser. This smaller diameter impeller, required because of the space limitations in the stage of the pump casing, provides a pump with less hydraulic performance per stage. For example, pump capacity is directly proportional to impeller diameter change; pump head is proportional to the square of diameter change; and power is proportional to the cube of the diameter change. In addition, the smaller diameter impeller of the prior art creates turbulence and extra circulation resulting in decreased efficiency since any abrupt turns or changes in velocity or direction of the fluid results in less efficiency.

SUMMARY OF THE INVENTION It is therefore a primary object of the invention to provide a pump stage with improved hydraulic output characteristics and one which will provide an efficient centrifugal pump by eliminating the area of turbulence and extra circulation between the impeller and the diffuser by making the necessary fluid turn in the impeller rather than the diffuser.

It is another object of the present invention to provide an impeller of a larger effective diameter without enlarging the outer pump casing.

It is still another object of the invention to provide a pump stage, as above, with an impeller which changes the direction of the high velocity fluid before it leaves the impeller and directs it axially into the diffuser.

It is an overall object of the present invention to decrease the number of stages within a pump over that required by a prior art without any loss of output.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial side elevation, partially in section, of a multistage centrifugal pump depicting one of the improved stages;

FIG. 2 is an enlarged cross section of the improved stage depicted in FIG. 1;

FIG. 3 is a partial sectional view taken substantially along line 33 of FIG. 2 and depicting the configuration of the diffuser and the passage of liquid therethrough; and,

FIG. 4 is a partial sectional view taken substantially along line 4-4 of FIG. 2 and depicting the configuration of the impeller and the passage of liquid therethrough.

DESCRIPTION OF THE PREFERRED EMBODIMENT A centrifugal pump embodying the concept of the present invention is designated generally by the numeral 10 in FIG. 1 and has an outer casing or shell 11 which can house a plurality of stages, generally indicated by the numeral 12, as well as other conventional pump components. The upper end of casing 11 communicates with a threaded coupling (not shown) for connection with the usual outlet pipe, and at the lower end, the casing 11 can be suitably attached to another casing which carries an intake end cap, pump motor, and the like, all conventional items which are not shown herein. Each stage 12 includes a housing 13, a diffuser 14 mounted within housing 13 in a nonrotatable manner, and an impeller 15 which is clearanced to rotate with housing 13.

The impeller 15 has a central hub portion 16 which is of a configuration such that it can readily be affixed to and therefore rotatably driven by pump shaft 17. A rear or vane plate 18 extends radially outwardly from hub 16 and can carry guide vanes indicated generally by the numeral 20 and hereinafter described in detail. The impeller 15 also has a front shroud 21 which terminates radially inwardly in an annular boss or neck 22 defining an aperture 23 concentric with hub 16 and forming therewith with an annular inlet for the liquid. As seen in FIGS. 1 and 2, the impeller shroud 21 extends radially beyond the diameter of vane plate 18 and thereafter terminates in an axially upwardly directed flange 24 having a diameter just less than that of the housing 13 so as to be freely rotatable therein.

The impeller guide vanes 20 are best shown in FIG. 4 as being crescent-shaped and extending from within the annular inlet to the outer edge of flange 24. Each vane 20 can be made in one piece and conveniently mounted between impeller vane plate 18 and shroud 21 or can be made in two segments 20A and 2013.

When manufactured in two segments the vane plate 18 integrally carries inner vane segments 20A and impeller shroud 21 carries outer vane segments 208 (FIG. 4). As shown in FIG. 2, the vane segment 20B extends axially upwardly above the end of shroud 21 to a point generally even with vane plate 18. Each outer vane segment includes a lug 25, each of which are received by complementary bores 26 in vane plate 18 wherein they are cemented or fastened by other suitable means. In such a manner, the vane plate 18 and shroud 21 are attached to form the impeller 15. In addition to this interconnection, as shown in FIG. 4, the radially outer end of vane segments 20A and radially inner end of vane segment 20B are beveled so that they will overlap, as at 28, at which point they may be cemented or otherwise fastened. Thus, the impeller is an integral unit including plate 18 and shroud 21 with vanes therebetween.

The diffuser 14 is mounted within the housing 13 and includes a front plate 30, a rear plate 31, a series of guide vanes 32 and a like number of helical fins 33. The front plate can be cast from a suitable plastic material and includes a central hub 34 which is provided with an annular metallic insert 35 to form a bearing surface for the impeller hub 16. The guide vanes 32 which are shown as being segmented similar to impeller vanes 20, can be formed integral with the plate 30 and provided with lugs 36 which are received in apertures 38 in rear plate 31 and cemented therein to form the integral diffuser 14. The rear plate may be cast from plastic or other suitable material and may be integral with the stage housing 13.

The front plate 38 extends radially outwardly from hub 34 to a diameter corresponding to that of the housing 13. The helical fins 33 are fixed to the periphery of plate 30, can be cemented to the housing 13, and extend to the rear plate 31.

As best shown in FIG. 3, each vane 32 has a convex surface 39 and a concave surface 40, with the concave surface extending, as by elements 41, to the housing 13 between the fins 33 and the rear plate 31. The fins 33, vanes 32, and vane extension elements 41 cooperate with the housing 13 to form spirally inclined entrance passages 42 for fluid being expelled from the impeller, to transfer the fluid toward the hub 34 and the rear plate 31. Thus, as shown by the arrow in FIG. 3, the fluid enters the diffuser and passes on fin 33 between convex surface 39 on one vane 32 and the housing 13. As the fluid continues, it contacts the vane extension element 41 and then the concave surface of the next vane 32 as it moves toward the hub 34.

In operation, the liquid initially flows into the pump 10 through an inlet at the bottom thereof (not shown) and fills a chamber 50 defined by the configuration of a bearing housing 51. The housing 51 gives stability to the shaft 18 and maintains the vertical position of the stage in that it engages the bottom of the stage housing 13 and in that it carries an annular metal insert 52 which engages the annular boss 22 of impeller shroud 21. In addition, housing 51 rides, in a manner not shown, on a bearing shaft sleeve 57 which is driven by the shaft 17.

The liquid then flows axially through the housing 51 and the impeller aperture 23 and is turned generally radially as it passes between vane plate 18 and impeller shroud 21. As the impeller rotates, the vanes 20 drive the liquid generally radially until it reaches the axial flange 24 where the liquid is guided and turned a second time exiting the impeller as it enters, axially. Because the liquid exists the impeller substantially axially, there is no wasted space radially beyond the diameter wherein the liquid would be diverted from radial movement. Also, the movement of the axial flange 24 with the impeller 15 minimizes any frictional drag on the liquid attendant those impellers which direct a stream of radially moving liquid against a stationary wall such as the stage housing or equivalent structure. Of course, the increased diameter of the impeller has several beneficial results such as: more velocity per equivalent amount of power, a greater output with the same number of stages as a conventional pump, or alternatively employment of less stages and/or amount of power to yield the desired output of a conventional pump.

Beyond the impeller 15, the axially moving liquid enters the spirally inclined passages 42 in the front wall 30 of the diffuser 14. As it moves radially inwardly and upwardly, in the manner previously described, the fluid approaches an aperture 53 in rear plate 31, with the velocity of the liquid having been reduced by the stationary vanes 32 within the diffuser 14 while pressure is proportionately increasing.

AS the fluid exits from aperture 53, it can be expelled from the pump, if the pump were one having a single stage, or if a multiple stage pump were involved, the fluid could go directly to another impeller with the hubs thereof butting together. The specific pump shown herein includes one stage, after which the fluid passes through a bearing housing 54 shown in FIG. 1 and similar to housing 51. Housing 54 is nonrotatably carried within casing 11 and includes a plurality of web members 55 which extend inwardly to an annular collar 56 which rides on a bearing shaft sleeve 58 driven by shaft 17. Thus, as liquid passes through aperture 53 of diffuser 14, it flows into achamber 61, through webs 55 and into a constricting chamber 62 leading either to the impeller of a subsequent stage or out of the pump.

From the foregoing description it should be apparent to one skilled in the art that the improved stage disclosed herein provides greater, more efficient output in a multistage centrifugal pump of the type contemplated.

What is claimed is:

1. A stage for a centrifugal pump having an axially extending driven shaft comprising a housing, impeller means within said housing for receiving and imparting velocity to a fluid material, and diffuser means fixed to said housing for decreasing the velocity and increasing the pressure of the fluid material, said impeller means including a hub rotatably driven by the driven shaft, a first plate, a substantially flat second plate extending radially from said hub, and vane members joining said first plate and said second plate, said first plate having a diameter greater than that of said second plate and peripherally terminating in an axially directed flange, said vane members extending outward from approximate said hub to the outer diameter of said first plate and beyond the outer diameter of said second plate and extending axially above said first plate and generally axially even wirh said second plate so that the fluid material received by said impeller means passes between adjacent of said vane members and said first and second plates and is guided around the outer end of said second plate to be turned by said axially directed flange of said second plate and axially expelled from said impeller means to said diffuser means.

2. A stage for a centrifugal pump as in claim 1, wherein said diffuser means includes a hub, a first plate extending radially from said hub, a second plate, a series of peripheral passages for the ingress of fluid material from said impeller means, said passages defined by crescent shaped vane members joining said first plate and said second plate and having concave and convex surfaces, by helical fin means for directing the fluid material between the concave surface of one said vane member and the convex surface of an adjacent said vane member, by said housing, and by said first and second plates of said diffuser means so that fluid material directed by said axially directed flange is guided by said passages from said first plate of said diffuser means to said second plate of said diffuser means.

3. A stage for a centrifugal pump as in claim 2, wherein said hub of said diffuser means receives said hub of said impeller means.

4. A stage for a centrifugal pump as in claim 2,

wherein said helical fin means are affixed to the periphery of said first plate of said diffuser means and to said housing, said series of peripheral passages for the ingress of the fluid material being further defined by vane extension members fixed to said housing, the fluid material entering said diffuser means on said helical fins and passes first between a convex surface of said vane member and said housing to further contact said vane extension member prior to contacting the concave surface of said adjacent vane member.

5. A stage for a centrifugal pump as in claim 2, wherein said second plate of said diffuser means extends to the periphery of said housing, said second plate of said diffuser means having an aperture therethrough concentric with and of a larger diameter than said hub of said diffuser means for the egress of the fluid material therefrom.

6. A stage for a centrifugal pump as in claim 5, wherein said vane members of said diffuser means are carried by said first plate of said diffuser means and extend radially outwardly from said aperture of said second plate of said diffuser means to the periphery of said housing.

7. A stage for a centrifugal pump as in claim 1, wherein said vane members include inner vane segments and outer vane segments.

8. A stage for a centrifugal pump as in claim 7, wherein said inner vane segments are carried by said second plate and said outer vane segments are carried by said first plate.

9. A stage for a centrifugal pump as in claim 7, wherein said outer vane segments extend radially to the periphery of and axially above said axially directed flange of said first plate.

10. A stage for a centrifugal pump as in claim 1, wherein said first plate has an aperture therethrough concentric with and of a larger diameter than said hub for the ingress of the fluid material into said impeller means.

Claims

4. A stage for a centrifugal pump as in claim 2, wherein said helical fin means are affixed to the periphery of said first plate of said diffuser means and to said housing, said series of peripheral passages for the ingress of the fluid material being further defined by vane extension members fixed to said housing, the fluid material entering said diffuser means on said helical fins and passes first between a convex surface of said vane member and said housing to further contact said vane extension member prior to contacting the concave surface of said adjacent vane member.