US3506374A

US3506374A - Self-priming pump

Info

Publication number: US3506374A
Application number: US734334A
Authority: US
Inventors: William K Kaebich
Original assignee: Decatur Pump Co
Current assignee: BURKS PUMPS INC A CORP OF DE
Priority date: 1968-06-04
Filing date: 1968-06-04
Publication date: 1970-04-14
Anticipated expiration: 1987-04-14

Description

April 14, 1970 w. K. KAEBICH SELF-PRIMING PUMP 2 Sheets-Sheet 1 Filed June 4, 1968 INVENTOR.

file Z2 z By Q @WATTORNEYS April 1970 w. K. KAEBICH 3 505 374 SELF-PRIMING PUMP Filed June 4, 1968 2 Sheets-Sheet 2 Z Z g.4

I N VENI'OR.

, g zz'am fiffaaz'ak V a @ATTORNEYS United States Patent 3,506,374 SELF-PRIMING PUMP William K. Kaebich, Decatur, Ill., assignor to Decatur Pump Company, Decatur, Ill., a corporation of Illinois Filed June 4, 1968, Ser. No. 734,334 Int. Cl. F04d 9/02 U.S. Cl. 415-210 13 Claims ABSTRACT OF THE DISCLOSURE A self-priming centrifugal pump which includes a diffuser disc and impeller rotatably positioned adjacent the diffuser disc. The diffuser disc includes a plurality of vanes spiraling radially outwardly and the impeller is rotatably positioned adjacent the diffuser disc radially inwardly of the vanes. The spacing between the vanes is greater than the spacing between the remaining vanes. A directional lip is formed on the diffuser disc and extends radially outwardly therefrom and positioned within the spacing of greater diameter.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to self-priming centrifugal pumps and more particularly to centrifugal pumps of the diffuser type which has a rotatable impeller positioned adjacent a diffuser disc.

Description of the prior art Centrifugal pumps of the prior art are commonly thought of as being efficient devices for moving fluids. However, such centrifugal pumps have a basic and inherent problem in possessing relatively poor self-priming characteristics. There are several methods of improving the priming ability of centrifugal pumps. One of the methods is the recirculation method which provides an effective prime cycle. However, this method lowers the efficiency during the pumping cycle because of the inherent recirculation. The recirculation can be eliminated by plugging or restricting recirculation ports either manually or automatically. However, this requires additional parts and makes the pump look more complicated and reduces the reliability and increases the possibility of frequent servicing. Such pumps of the prior art are shown in the Burks Patent 1,978,400.

SUMMARY OF THE INVENTION Accordingly, one of the primary objects of the present invention is to provide a self-priming centrifugal pump which has improved self-priming characteristics.

Another object of the present invention is to provide a self-priming centrifugal pump which is simple in construction and which is efficient and reliable in operation.

Briefly, the self-priming centrifugal pump of the present invention utilizes a priming principle known as diffuser priming. In diffuser priming, many prime-inducing meth ods may be used. In some methods, liquid is drawn through openings in the backside of the diffuser near the low cutwater. Other methods position the cutwaters of the diffuser with some cutwaters close to the periphery of the impeller and other cutwaters located varying distances away from the periphery of the impeller. The priming process requires that liquid surrounding the diffuser in the lower cavity of the pump casing be placed in contact with the tips of the vanes of the impeller during the prime cycle. This relatively air-free liquid is forced back into the impeller vane area because of the difference in pressure between the casing cavity and the vacuum condition at the eye or entrance of the impeller. The liquid which engages the tips of the impeller 3,506,374 Patented Apr. 14, 1970 vanes mixes turbulently with the air which is drawn up through the suction pipe. This mixture of air and liquid is discharged out of the impeller and separated from the impeller by the cutwaters of the diffuser. The air and liquid are separated as they are discharged into the upper cavity of the pump casing. The air is discharged out of the discharge pipe and the liquid falls back into the lower cavity of the casing to once again be used in the printing process.

In this invention, it is the purpose to use extremely simplified construction and machining of the impeller and diffuser, yet achieve rapid and positive priming with a minimum loss in pumping efficiency during the pumping cycle. This has been accomplished by the following meth 0d. The impeller is designed with accepted hydraulic practices using the latest principles giving high efficiency and pressure head for a given impeller diameter. This includes the determination of the optimum number of vanes required for a desired performance. However, the diffuser for this pump is designed to use a completely different diffuser principle from normal practice. The cutwaters used are the same number as the number of vanes used in the impeller. This is not normal hydraulic design practice. The cutwater spacing, or radial location of the cutwaters, is equal to one (1) plus the number of vanes for example, with 4 impeller vanes, there will be 4 diffuser vanes with the diffuser vanes spaced as though there were 5 vanes. In effect, this gives a double space at the lower part of the diffuser section.

Another feature of the diffuser design of this invention is a large directional lip located adjacent to the double space. The directional lip and double space channel direct the liquid to the impeller periphery thereby permitting large surface areas of the impeller 0D. to be in pressure contact with low velocity air-free liquid. This gives a large and very effective mixing surface for entraining and mixing liquid with air.

In this design, all of the cutwaters are located at the same clearance (radial distance) from the impeller 0D. This enhances the effectiveness and increases the efficiency of priming. This clearance is usually & but clearances ranging from & to A are common and acceptable. This uniform clearance also has the mechanical feature of, simplifying the casting and machining operations required. The multiple vane cutoff arrangement serves to rapidly and efficiently separate the air and liquid mixture as it is expelled from the impeller and gives multiple surface areas discharging into the upper area of the pump casing.

It is important that the directional lip of the diffuser be located in the area of the casing which is considered the fourth quadrant when looking at a cross-section with. the impeller rotating in a counterclockwise direction. Positioning of the directional lip in this quadrant takes maximum advantage of the pressure differential between the atmospheric pressure in the pump casing and the vacuum condition at the entrance to the eye of the impeller. The extra large surface area of the impeller periphery placed in pressure contact with the air-free liquid ensures a rapid and positive prime cycle. The directional lip encourages effective air separation, and serves as a guide to channel the liquid to the impeller periphery.

In keeping with the definition of a true centrifugal pump the impeller, diffuser and pump casing must be part of a unitized design to enable the pump to reprime, after the pumping cycle has been shut off, without addi tion of liquid to the system or pump casing. This requires that a sufficient quantity of liquid be trapped in the pump casing after the pump has been shut off and liquid has siphoned back through the pump to the source of liquid. The combination of parts illustrated according to this invention require a very minimum amount of liquid to be trapped in the pump, and yet ensures rapid, reliable and uniform priming to lift liquid much higher than is often obtainable with other diffuser priming methods.

This priming principle, when compared with other methods and other pumps offers reliable rapid priming rates. For example, a pump having similar head and capacity performance characteristics has been found to be capable of priming or evacuating a 9 ft. long vertical column of 1" pipe, when compared to a pump using my new priming principle that will uniformly prime as much as 15 ft. of vertical column of 1" pipe in one half the time. The priming takes place at a very uniform rate. The present invention would also permit continued priming on to as much as 20 ft. compared with the maximum 9 ft. lift with other designs of pumps having the same general size and service capabilities.

From the general objects and features set forth hereinabove, it will be apparent that other objects, features and advantages will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawings wherein like reference numerals throughout the various views of the drawings are intended to designate similar elements and components.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a sectional view of a self-priming centrifugal pump taken along the center line thereof;

FIGURE 2 is an end sectional view of the self-priming pump of FIGURE 1;

FIGURE 3 is a side sectional view of a diffuser disc used in the pump of FIGURE 1;

FIGURE 4 is an elevational plan view of the diffuser disc of FIGURE 3; and

FIGURE 5 is a prospective view of the impeller used in the pump of FIGURE 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Seen in FIGURE 1 is a self-priming centrifugal pump constructed in accordance with the principles of this invention and is designated generally by reference numeral 10. The pump includes a first casing 11 which is secured to one end of a motor 12. The motor 12 includes a shaft 13 which extends into the casing 11 through an aperture 14.

A shaft seal, consisting of two basic elements, a stationary member 1 and a rotating member 18, which are positioned about the shaft 13 in abutting relationship with the periphery of the aperture 14 to provide a fluid tight seal therebetween. Also secured about the shaft 13 is a shim washer 20. The motor 12 includes a flange 21 which receives a mating annular portion 22 of the casing 11.

Secured to the threaded end portion of shaft 13 is an impeller 24. The impeller 24 is positioned adjacent the diffuser disc 26 which is aligned and held in position on the casing 11 by a pin 27 which extends through an aperture 28. The diffuser disc 26 has a suction eye or aperture 29 formed therethrough.

A second casing 30 is secured to the first casing 11 by means of bolts or the like. A gasket 31 is provided be tween the two casings 11 and 30 to form a fluid tight seal therebetween. The casing '30 includes a wall portion 32 through which an aperture 33 is formed. The aperture 33 is in alignment with the suction eye 29 of the diffuser disc 26. A seal 34 is positioned about a flange formed on the diffuser disc 26 and forms a fluid seal between the wall portion 32 surrounding the aperture 33 and the rear portion of the diffuser disc. Therefore, it is seen that the wall portion 32 together with the diffuser disc' 26 divides the interior of the casing 30 to form a suction chamber 36 and a discharge chamber 37.

A threaded pipe fitting 38 is formed in the casing '30 to receive a suitable pipe or conduit which may extend .4 downwardly into a well or reservoir of fluid. Also formed in the casing 30 is a threaded fitting 39 which may be connected to an outlet pipe for discharge of the fluid. The discharge chamber 37 is annular about the spacer 34 and flanges adjacent thereto and also forms a reservoir or fluid retaining chamber 40.

One feature of the present invention is a directional lip 41 which is formed on the diffuser disc 26 and extends downwardly into the fluid retaining chamber 40. A plug 42 is provided in the casing 30 to close off an opening within the fluid retaining chamber 40. Therefore, if for any reason it is necessary to drain the fluid which remains in the chamber 40 the plug can be easily removed for such function. Also, a plug 43 is provided in the upper portion of the casing 30 for adding fluid to the centrifugal pump housing for initial starting of the pump. That is, when the pump is initially connected to a fluid supply line there is no liquid within the fluid retaining chamber 40. Therefore, fluid may be added to the casing by removing the plug 43 and adding fluid to the plug opening.

Seen in FIGURE 2 is an end sectional view of the casing 30 showing the relation between the diffuser disc 26 and the impeller 24. In FIGURE 2 the diffuser disc 26 is shown to have a second aperture 44 for receiving another pin 45 to align and secure the diffuser disc to the casing 11. In each of the four corners of the casing 30 holes 46 are provided for receiving bolts to secure the casing 30 to casing 11.

The diffuser disc 26 includes a plurality of

vanes

47, 48, 49 and 50 which extend radially outwardly in a spiraling fashion beginning at a first diameter and terminating at a second diameter which is greater than the first diameter. The radially inward portion of the vanes 47-50

form cutwaters

51, 52, 53 and 54 respectively. The cutwaters 51-54 are formed on the same diameter of the diffuser disc thereby simplifying the machine operation of forming the disc. Also, it will be noted that the spacing 56 indicated between the cutwater 51 and the impeller 24 is the same between each of the cutwaters and the impeller.

As best seen in FIGURE 3, the vanes 47 and 48, extend axially outwardly of the diffuser disc 24 a distance d from a surface 57. The distance d is selected to be substantially equal to the distance of the vanes formed on the impeller 24.

FIGURE 4 clearly illustrates the construction of the diffuser disc 26. The directional lip or web 41 is shown formed in the fourth quadrant of the disc between

vanes

47 and 50. The spacing between

vanes

47 and 50 is twice that of the spacing between vanes 47 and 48, or vanes 48 and 49, or

vanes

49 and 50. It will be noted that the spacing from our tradial location of the vanes 47-50 is equal to one (1) plus the number of vanes formed on the disc. Also the directional lip or web 41 is formed in this double spaced region to increase the efficiency and operation of the recirculating operation of the pump.

FIGURE 5 is a detail showing of the construction of the impeller 24. The impeller 24 also includes a plurality of vanes, 57, 58, 59 and 60. The vanes 57-60 on the impeller 24 extend axially from the face of the impeller a distance approximately equal to d which is also the distance of axial extent of the vanes formed on the diffuser disc 26. It will also be noted that the spacing 56 between the cutwaters 51-54 and the impeller 24 is preferably The primary features of the present invention are the I provision of the directional lip or web 41, and the double casing and the vacuum condition at the entrance or eye 29 is obtained. This provides extra large surface area of the impeller periphery and the air-free liquid within the fluid retaining chamber 40 to ensure rapid and positive priming. The unique design of this diffuser does not require any individual vane modifications or cutwater modifications to channel where prime-liquid is in pressure contact with approximately 2/5 of the impeller periphery. It has been found that the greater area in pressure contact with the impeller periphery, the greater the efliciency of mixing air and water. The directional lip or web 41 encourages effective air separation and serves as a guide to channel the liquid from the liquid retaining chamber 40 to the impeller 24.

Accordingly, the present invention provides a selfpriming centrifugal pump with a unique diffuser disc and impeller arrangement for effective priming of the pump. It will be understood that other combinations of impeller vanes and diffuser cutwaters can be used to obtain the advantages of this invention. The basic configuration required is that there must be a double spacing between two of the vanes of the diffuser disc. The enlarged opening may have a directional lip which is located in the fourth quadrant of the disc for channeling the air-free priming liquid into pressure contact with the large exposed impeller periphery. This ensures turbulent mixing of air and liquid at the impeller vane tips.

The location of the directional lip 41 within the fourth quadrant of the diffuser disc 26 provides optimum results for both self-priming and pumping operations. In the preferred arrangement of the present invention the impeller 24 has approximately 2/5 of the impeller periphery in pressure contact with the liquid within the pump. This provides maximum mixing efficiency of air and liquid since effective mixing is a function of the exposed area of the impeller. Therefore, the double space in the fourth quadrant between

vanes

47 and 50 provides maximum mixing of air and liquid since no full or partial vane is provided in this area to disturb the mixing-air entraining process. Also, the radial extent of the beginning of each of the cutwaters 51-54 is identical and, the radial clearance between the impeller 24 and the cutwaters is the same throughout the circumference of the diffuser disc and the impeller. Therefore, variations and modifications may be easily effected without departing from the spirit and scope of the novel concepts of this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A self-priming centrifugal pump comprising a housing having an inlet, an outlet and a fluid passage communicating said inlet with said outlet; a diffuser disc having a series of at least three equally spaced vanes formed thereon in consecutively in the upper first, second and third quadrants, each vane spiraling radially outwardly beginning at a first diameter spaced from the center of said disc and terminating at a second diameter which is greater than said first diameter, and trailing portions of said series of vanes overlapping vanes in the lowermost fourth quadrant being spaced from one another such that the spacing between two of the vanes is a greater distance than the spacing of the other vanes to the extent that the trailing portions of the vanes do not overlap, said diffuser disc further having an aperture substantially at the center thereof and radially inwardly of said first diameter, said diffuser disc positioned in said housing such that said aperture forms part of said fluid passage; and an impeller rotatably positioned within said housing adjacent said diffuser disc and radially inwardly of said vanes, wherein prime liquid is in pressure contact with approximately 2/5 of the impeller periphery.

2. A self-priming centrifugal pump according to claim 1 further including a directional web formed on said diffuser disc and extending radially outwardly therefrom and between the vanes having the greater spacing therebetween whereby a convergent channel is formed to introduce fluid to an impeller periphery thereby permitting large surface areas of the impeller to be in pressure contact with low velocity air-free liquid.

3. A self-priming centrifugal pump according to claim 2 wherein the spacing of greater distance is approximately twice the spacing of the other vanes.

4. A self-priming centrifugal pump according to claim 3 wherein the directional web of the diffuser is located in the fourth quadrant to thereby take the maximum advantage'of the pressure differential between the atmosphere pressure in the pump casing and the vacuum condition at the entrance to the eye of the impeller so that the extra large surface area of the impeller periphery is placed in pressure contact with the air-free liquid to insure a rapid and positive prime cycle.

5. A self-priming centrifugal pump comprising a housing having an inlet, an outlet and a fluid passage communicating said inlet with said outlet; a diffuser disc having on one side a plurality of vanes spiraling radially outwardly, each said vane having an inner end on a circle having a first radius spaced from the center of said disc and each said vane having an outer end on a circle having a second radius which is greater than said first radius, each of said vane inner ends forming a cutwater, said vanes and cutwaters being substantially equally spaced from each other in consecutively in the upper first, second and third quadrants of said disc and having trailing portions that overlap, each vane in the lower fourth quadrant being spaced from each a greater distance than the spacing between each vane in the upper first, second and third quadrants so that the vanes do not overlap, said diffuser disc being secured in said housing to divide said fluid passage into a suction chamber and a discharge chamber; and an impeller rotatably positioned within said housing adjacent said one side of said diffuser disc radially inwardly of said first diameter to cause fluid to flow from said suction chamber to said discharge chamber.

6. A self-priming centrifugal pump according to claim 5 wherein said greater distance is approximately twice the spacing of the other vanes.

7. A self-priming centrifugal pump according to claim 6 further including a directional web formed on said diffuser disc and extending radially outwardly therefrom and positioned in said fourth quadrant between said vanes having a distance of approximately twice the distance of the other vanes.

8. In a self-priming pump of the type having a rotary impeller, means for supporting said impeller for rotation about a substantially horizontal axis, wall structure defining a fluid retaining chamber for a reserve of liquid in which said impeller is rotatable and defining an inlet communicating centrally with said impeller and an outlet leading from said chamber, and a diffuser disc having consecutively upper first, second, third quadrants and a lower fourth quadrant, said disc having a plurality of vanes spaced about the periphery of said impeller beginning at a point in close proximity with said impeller periphery at a first fixed radius and spiraling forwardly and outwardly therefrom to a second fixed radius providing substantial peripheral overlap of the beginning point of the succeeding vane, said fourth quadrant being in said fluid retaining chamber, each said vane in said fourth quadrant having a larger pressure contact area than said vanes in said first, second and third quadrants the spacing between the vanes in the fourth quadrant being such that the trailing ends do not overlap.

9. A self-priming centrifugal pump according to claim 8 wherein said diffuser disc includes cutwaters, at the beginning of each vane, said cutwaters being uniformly spaced from theimpeller periphery.

10. A self-priming centrifugal pump according to claim 9 wherein said impeller has a plurality of equally spaced vanes thereon, the number of said cutwaters being the same as the number of vanes onsaid impeller, the cutwater spacing or radial location of the cutwaters being equal to one plus thenumber of impeller .vanes so. that the diffuser vanes and cutwaters'will be spacedas though there were one more than the number of impeller vanes, 21 double space occurring between the cutwaters and diffuser vanes in the fourth quadrant.

i 11. A self-priming centrifugal pump according to claim 10 wherein said cutwaters are of identical configuration. 12. A self-priming centrifugal pump according to claim 8 wherein said pressure contact area on each vane in said fourth quadrant is spaced at least twice the spacing distance between the vanes in the first, second and third quadrant.

13. A self-priming pump capable of producing a priming cycle and a pumping cycle, comprising a casing having a priming chamber area, said casing having an inlet outlet, a rotary impeller capable of producing an airliquid mixture at its periphery, a diffuser disc having upper first, second, third quadrants and a lower fourth quadrant, said diffuser having more than two vanes, liquid passages between said vanes, liquid passages between said vanes communicating to and from said impeller periphery and said primingchamber area in said casing, said vanes; being spaced about said impeller to an extent of less than 360 with the extent of the, disc having no vanes being located in said fourth quadrant at the bottom of said diffuser in said priming chamber area, each vane beginning at a first point in close proximity to said impeller periphery and on a fixed diameter and spiraling forwardly and outwardly therefrom to a point providing substantial peripheral overlap with the beginning point of the succeeding vanes, except for the large space with no overlap in the fourth quadrant, and a directional web extending from said diffuser and being located in the fourth quadrant at the bottom thereof in said priming chamber area.

References Cited UNITED STATES PATENTS HENRY F. RADUAZO, Primary Examiner 1 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,506,374 Dated April 14, 1970 Inv nt fl William K. Haebich It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

3 Sheet 15, change "Kaebich" to --Haebich--; Sheet 2, change "Kaebich" to --Haebich--; Column 1, after title change "Kaebich" to --Haebich--; Column 1, line 16, after the word "is" insert --such that the spacing between two of the vanesee Column 3, line 48 change "1" to --16--; Column 5, line 7 change "where" to --wherein.

SIGNED SEALED mum;

Mum," wmuu 1:. mm. .m. Atteating Offiocr Omission or Patents