US1967182A - Centrifugal pump - Google Patents

Description

July 17, 1934;

F. B. ALLEN CENTRIFUGAL PUMP Filed April 3, 1954 3 Sheets-Sheet l Snnentor PIP/wk BALZf/V (Ittornegs July 17, 1934. F. B. ALLEN CENTRIFUGAL PUMP Filed April 3, 1934 3 Sheets-Sheet 2 ZSnnentor grmxvkfi/aun/ Gttomegs July 17, 1934. F. B. ALLEN CENTRIFUGAL PUMP Filed April 3, 1934 5 Sheets-Sheet 3 Smoentor Z-TAA/A B- AME/V (Ittornegs Patented July 17, 1934 PATENT OFFICE CENTRIFUGAL PUMP Frank B. I

Pennsylvania Allen, Lower Merion Township, Montgomery County, Pa., assignor to The Allen- Sherman-Hoff Company,

a corporation of Application April 3, 1934, Serial No. 718,872

.12 Claims. (01. 03-414) This invention relates to pumps and more particularly to centrifugal pumps for handling abrasive carrying fluids such as mixtures of sand and gravel with water. 5 In pumping abrasive carrying fluid by means of centrifugal pumps a great deal of trouble has been experienced due to the rapid wearing'of the parts of the'pump structure under the abrasive action of the material being pumped. In order to overcome this trouble the pump casings and impellers have been made of the hardest alloy steels obtainable but even these structures wear out and become useless after being in use for a;

that the life of a pump may be very greatly increased by so sheathingthe inner surfaces of the pump structure with rubber. Apparently the particles of abrasive material in the fluid being pumped glance off from the resilient rubber without appreciable wearing away thereof. In constructing centrifugal pumps having rubber linings and rubber covered impellers considerable diiilculty has been experienced due to the entry of theliquid and abrasive material between the rubber lining or covering and the metalparts of the structure which support the rubber. As the fluid being pumped is under considerable pressure at certain parts of the pump there is a tendency for the fluid to work into the exposed cracks liquid and abrasive material work in between the rubber. covering of the impeller and .the rigid backing structure thereof because, when the material does so work in, the centrifugal force set up by the rapidly rotating impeller immediately is effective on the material to tend to force it toward the outer periphery of the impeller, thus separating the rubber and the rigid backing and or joints where the resilient covering joins the causing blisters at or near the periphery of the impeller. i

It isamong the objects of my present invention to provide a rubber covered impeller structure for centrifugal pumps in which the blistering of the rubber due to the entry of material between the covering and the backing is eliminated, thus greatl'y increasing the life of thepump, avoiding shut downs for repairs and increasing the efliciency of the pump by always maintaining the proper contour of the impeller blades. i v In-pumps of this type which have been made prior to my invention and with which I am familiar, it has been necessary, due to the structure of' these pumps and the fact that the linings must be vulcanized to the metal parts of the pump, to return' the metal frame work to the factory when it was desired to replace the rubber covering of either the casing or impeller. It is a-further ob ject of my invention to eliminate this undesirable feature and provide a rubber lined pump' having rubber coverings, both for the casing and impeller, which can readily be replaced on the job without return to the factory.

I have found that, rather than attempting to completely seal all joints between the rubber covering of the impeller and the rigid structure of the impeller and to vulcanize or otherwiselsecure the rubber to the frame of the impellerflmuch better results can be obtained by providing means whereby any material which may get in between the rubber covering and the frame may readily escape therefrom into the pump housing. .By thus preventing the building up of a pressure between the rubber covering and the impeller frame the formation of harmful blisters and deformations of the rubber covering is'eifectively prevented.

In the accompanying drawings I have illustrated a centrifugal pump embodying my invention, two arrangements for preventing the formation of blisters on the impeller being illustrated.

In the drawings-- Figure 1 is a side elevation, partly in section, of a centrifugal pump adapted to pump abrasive carrying fluids and incorporating the features of my invention.

Figure 2 is a fragmentary enlarged view of a portion of the pump shown in Figure 1 illustrating the impeller and casing on a larger scale, the impeller being shown in partial cross section taken on line 2-2 of Figure 3.

Figure 3 is an end elevation, partly in section, looking at the inlet end of my improved impeller and illustrating one arrangement of pressure relieving perforations.

Figure 4 is a cross sectional view taken on line 4--4 of Figure 3.

Figure 5 is a cross sectional view of another embodiment of my improved impeller construction taken on line 5--5 of Figure 6.

Figure 6 is a cross sectional view of the impeller shown in Figure 5 and taken on line 66 of Figure 5.

Figure '7 is a detached side elevation of my improved unitary rubber liner for the pump housing and discharge outlet.

Figure 8 is a cross sectional view taken on line 8-8 of Figure 7.

Figure 9- is an end view, partly insection, taken from the inlet end of the pump of Figure 1.

Referring to Figure 1 which illustrates the general layout of my improved pump, the pump casing 1 may be mounted on a suitable base 2 and driven by a suitable prime mover through the shaft 3. The pump inlet 4 enters the center of the pump casing 1 on the side opposite the driving shaft 3 and the outlet (not shown in Figure 1) may be of the usual tangential type. The pump impeller A is carried by and rotates with the shaft 3. Impeller shroud or side disc portions B and C divide the interior of the pump housing 1 into a centralmain pumping chamber and auxiliary flushing water chambers disposed on either side of the main chamber. Clear flushing water is supplied to the auxiliary side chambers through the supply pipes 5 and 6, the pressure of the supply being maintained high enough to create a flow from the auxiliary chambers into the main chamber at all times during operation of the pump, thus positively preventing the entry of abrasive carrying material into the clearance spaces between the impeller and the pump housing.

As will be more fully described later the easing 1 is lined by a relatively soft rubber liner generally indicated by reference character D and the surfaces of the impeller which contact with the fluid being pumped are all formed by the rubber impeller covering generally indicated at E.

Rubber sealing rings F and G are disposed in the auxiliary clear water chambers and have portions which engage the impeller to regulate the flow of clear flushing water and to assist in preventing the entry of abrasive carrying material into the clearance spaces of the pump. The sealing ring member F is disposed on the inlet side of the pump impeller and comprises an outer sealing portion 7 adapted to engage the surface of the impeller shroud adjacent its outer periphery and an inner sealing portion 8 which engages the shroud adjacent its inner periphery. A ring member 9 is preferably disposed between the sealing ring F and the pump housing to press the portion '7 of the sealing member into engagement with the impeller. The inner sealing member 8 is so formed that pressure of the clear flushing fluid which enters through the pipe 5 acts upon the portion 8 to exert a force tending to hold it in engagement with the impeller.

The sealing member G on the shaft side of the impeller is similar to the member F and includes an outer sealing portion 10 held in engagement with the impeller by the ring member 11 but does not include an inner sealing member because there is no joint to be sealed at the inner periphery of the shroud on the shaft side of the impeller.

A hole 40 (see Figure 2) extends through the side of the casing into the clear water chamber on the shaft side of the pump. A test pipe 41, provided with a shut 01f valve 42, leads from this hole to any convenient testing point. When it is desired to determine whether or not the sealing members are functioning properly the valve 42 will be opened. If the water which is then discharged through the pipe 41 is perfectly clear the seals are working properly. If, however, the solution is cloudy or muddy it indicates that the seals are worn or for some other reason are functioning improperly and the pump can then be shut down for repairs before serious damage is done. A similar test pipe (not shown) may extend from the clear water chamber on the inlet side of the pump. in similar manner.

As can be clearly seen in Figure 5 my impeller is provided with three blades, generally indicated by the reference character H. These blades extend across between the impeller shrouds B and C and, when the impeller is rotated, act to draw fluid in through the inlet 4 and discharge it through the tangential outlet in the usual manner.

Referring now particularly to Figures 3, 4, 5 and 6, two embodiments of my particular improved pump impeller structure will be described.

The metallic disc 12 is carried by the hub 13 which may be threaded as at 14 to engage corresponding threads on the end of the drive shaft 3. The annular inlet side shroud ring 15 is spaced from the disc 12 by the blade reinforcing members 16, 17 and 18. As illustrated each of these members 16, 17 and 18 is drilled to accommodate three rivets (or other suitable fastening means) which extend through counter sunk holes in the disc 12 and the shroud ring 15 and are riveted over as at' 20 (see Figure 2) to form a rigid impeller frame structure.

The rubber covering for the impeller is preferably molded in one piece, the shape of which can be seen from the drawings and which includes a disc portion 21, an annular ring shroud portion 22 and impeller blades 23, 24 and 25 extending across between the disc 21 and the shroud 22. In assembling my impeller unit the flange 23' of the rubber impeller covering, which is formed at the outer periphery of the disc portion 21, is stretched over the edge of-the metallic disc member 12. Next the spacer blocks 16, 17 and 18, preferably of fiber, bakelite or similar non-metallic substances, are inserted in the holes 26, 27 and 28 which extend through the rubber blade portions 23, 24 and 25 respectively and the rivets 19 are placed in position through the disc 12 and the spacing and reinforcing blocks 16, 1'7 and 18. The shroud ring member 15 may then be inserted into the grooves formed in the rubber shroud member 20 by the flange portions 29 and 30. Next the ends of the rivets 19 are riveted into place to form a rigid structure and the annular metallic outside shroud members 31 and 32 are secured in place by screws 33. It will, of course, be understood that the above describedassembly steps may be varied if desired, the steps being described in this specification merely to assist in a clear understanding of'my impeller structure.

As is clearly seen in Figures 2, 4 and 6 the member 31 bears against the outer surface of the portions 29 and 30 of the resilient impeller covering and serves to hold the covering firmly in position on the impeller. In like manner the shroud ring 32' engages. the portion 23' of the impeller covering and holds it firmly in position on the disc 12.

In Figures 3 and 4 I have illustrated a plurality of holes 34 which extend inwardly from the periphery of the impeller through the rubber covering to the rigid frame structure. As is seen in Figure 3 the holes 34 are preferably equally spaced around the periphery of the impeller. One group of holes 34 extend inwardly to the outer edge of the shroud ring 15 and another set of perforations or holes 34 extend inwardly to the outer edge of the disc 12. I have. found that these holes may be readily formed in the rubber covering of the impeller by burning them through the rubber with a hot wire or by merely puncturing Puncturing the rubberber covering and the frame structure at the joints between the rubber flanges 30 and 23 and the impeller shrouds such material will be acted on by centrifugal force when the pump is rotated and will be discharged through the perforations 34 and carried into the main pumping chamber thus preventing an accumulation of material and building up of pressure causing the formation of blisters on the rubber covering.

In Figures 5 and 6 I have illustrated another arrangement-of perforations for preventing blistering which has proved very satisfactory under actual workingconditions. In the impeller shown in Figures 5 and 6 a perforation 35 extends through the rubber covering of each of the impeller blades from the outer surface of the rubher to the fiber core portions 16, 17 and 18. The perforations 35 extend from the outer trailing edge of the impeller inwardly and are preferably disposed on a substantially tangential line. As seen in Figure 6 the holes 35 lie on a plane cutting through the centers of the impeller blades. In operation the impeller rotates in the direction of the arrow of Figure 5 and it is my opinion that a zone of relatively low pressure is created. behind the trailing edge portions 36 of the impeller blades. The perforations or holes 35 thus are exposed at their outer ends to the low pressure zone and any material which enters between the rubber covering and the impeller frame will be acted upon both by centrifugal force and the'pressure differential between the high pressure portions of the pump and the low pressure zone adjacent the outer ends of the holes or perforations. This action effectively prevents the accumulation of material between the rubber covering and the impeller frame.

Referring nowparticularly to Figures 2, '7, 8 and9 my pump. housing includes a central section 43 in which is formed the usual volute shaped chamber 44. This central section is also provided with a tubular tangential outlet portion 44' improved rubber casing liner.

provided with an outlet portion 47 which fits in the tangential discharge outlet 44 of the central section of the casing. The outlet portion 47 of the rubber liner is formed with an outwardly extending flange 48 adapted to engage the end of the outlet portion 44 of the central section of the casing. Side flange portions 49 and 50 are formed at the edges of the volute portion of the rubber liner and are adapted to extend around the sides of the central section, as is seen in Figure 2.

As the rubber liner is relatively flexible it may be collapsed or deformed, when the pump is disassembled, and properly positioned within the central section. When the side plates 45 and 46 are secured in position the flanges 49 and 50 will be firmly clamped between the side plates and the central section of the housing. In like manner a discharge pipe 51 may be secured to the end of the tangential outlet 44' of the central section thus clamping the flange 48 firmly against the pump casing. This arrangement greatly facilitates the replacement of the rubber casing lining and eliminates the necessity for vulcanizing or otherwise securing or cementing the rubber lining to the casing.

It will be understood that where the term rubber covering is used in this specification and the appended claims it is intended to include any composition of rubber or other materials having the desired resilient characteristics and that where reference is had to perforations extending through the rubber covering or lining it is intended to include actual holes made in the rubber and also fissures which remain in the material after forcing an instrument such as an awl through the material. Where the term peripheral portion is used in this specification and the appended claims it is intended to refer to all points at or adjacent the periphery of either side disc or shroud of the impeller or the outer end portion of an impeller blade.

Although I have illustrated only two-arrangements of perforations it will be seen by those skilled in the art that the rubber covering of the impeller might be perforated at points other than those herein illustrated and described without departing from the spirit of my invention. Moreover, other modifications and variations may be made in the various parts of my improved pumping apparatus without departing from the spirit of my invention and I do not, therefore, wish to be limited to the exact form of my improved apparatus herein shown and described, but claim as my invention all embodiments thereof coming within the scope of the appended claims.

I claim:

1. In a pump of the class described, an im-- peller having a rigid frame structure, the surfaces of the impeller which contact with the fluid being pumped being covered with rubber or the like, said covering having an. opening therethrough extending from the outside of the covering adjacent the periphery of the impeller in- 1 for said frame having flanges adapted to extend around the edges of said shroud portions, said sheath having apertures through which said blade reinforcing members extend and perforations extending from the surface of the sheath to the m frame, and means for clamping said flanges of said sheath to said shrouds.

3. In a centrifugal pump, a housing, a removable rubber lining for said housing, an impeller having a rigid frame structure, a rubber covering for said frame, said rubber covering having a perforation extending through the covering from the outer surface thereof to the inner surface thereof, said perforation being disposed with its outer end adjacent the periphery of the impeller whereby material entering between said frame and covering may escape through said perforation into the pump housing.

4. An impeller of the type described comprising a disc portion, a hub on said disc, an annular shroud ring, independent spacing and impeller blade reinforcing members disposed between said disc and ring, means for'securing said disc, blade reinforcing members and shroud ring together to form a rigid impeller frame structure and a rubber covering adapted to cover said blade reinforcing members and the inner surfaces of said disc and shroud ring, said rubber covering having a perforation extending from a point substantially at a peripheral portion of said covering to said frame structure for permitting the escape of material from between said frame and said covering.

5. In a centrifugal pump, an impeller comprising a disc portion, an annular shroud ring, independent spacing and impeller blade reinforcing members disposed between said disc and ring, means for securing said disc, blade reinforcing members and shroud ring together to form a rigid impeller frame structure, and a one-piece rubber covering extending over said blade reinforcing members and the inner surfaces of said disc and shroud ring, said covering having portions extending around the outer edge of said disc and the outer and inner edges of said ring,

and means for clamping said last named portions of the rubber covering against the outer surfaces of said disc and ring.

6. In a centrifugal pump, an impeller comprising a disc portion, an annular shroud ring, independent spacing and impeller blade reinforcing members disposed between said disc and ring, means for securing said disc, blade reinforcing members and shroud ring together to form a rigid impeller frame structure, a one-piece rubber covering extending over said blade reinforcing members and the inner surfaces of said disc and shroud ring, said covering having portions extending around the outer edge of said disc and the outer and inner edges of said ring, and means for clamping said last named portions of the rubber covering against the outer surfaces of said disc and ring, said rubber covering having circumferentially spaced perforations extending therethrough adjacent the periphery of said disc and ring.

7. In a centrifugal pump, an impeller comprising a disc portion, an annular shroud ring, independent spacing and impeller blade reinforcing members disposed between said disc and ring,

means for securing said disc, blade reinforcing members and shroud ring together to form a rigid impeller frame structure, a one-piece rubber covering extending over said blade reinforcing members and the inner surfaces of said disc and shroud ring, said covering having portions extending around the outer edge of said disc and the outer and inner edges of said ring, and means for clamping said last named portions of the rubber covering against the outer surfaces of said disc andring, said rubber covering having perforations extending therethrough from the outer surface of the portions of said covering which cover said blade reinforcing members to the outer ends of said blade reinforcing members.

8. In a centrifugal pump, a housing, a rubber lining for said housing, an impeller rotatably supported in said housing, said impeller including a rigid frame structure and a one-piece rubber covering member adapted to cover the surfaces of said frame structure which would otherwise contact with the material being pumped, and means, comprising a perforation extending through the rubber covering from a point substantially at a peripheral portion of said covering, for permitting the escape of material entering between said frame structure and said covering.

9. In a centrifugal pump or the like, an impeller comprising a frame structure, a resilient covering for said frame structure, said covering having a perforation extending from a point substantially at a peripheral portion of said covering to said frame structure.

10. In a centrifugal pump or the like, an impeller comprising a frame structure, a resilient covering for said frame structure, said covering having a perforation therethrough extending from said frame to the outer surface of said covering and so disposed as to permit the escape of material from between said frame and said covering under centrifugal force created by rotation of the impeller.'

11. In a centrifugal pump or the like, an impeller comprising a frame structure, a resilient covering for said frame structure, said covering having a perforation extended from a point substantially at, a peripheral portion of said covering to said frame structure for permitting the escape of fluids and solids from between said frame and said covering under the influence of force set up when the impeller is rotating.

12. In combination in a centrifugal pump, a housing, a rubber lining for said housing, a rubber covered impeller rotatably supported in said housing, said impeller including a frame structure and a rubber covering therefor, said rubber covering having a perforation extending therethrough from a point on its outer surface adjacent a peripheral portion of the impeller to the inner surface of said covering adjacent said frame.

FRANK B. ALLEN.

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