US2163464A - Centrifugal pump - Google Patents

Description

June 20, 1939. D. LLEWELLYN 2,163,464

CENTRIFUGAL PUMP Filed April 15, 1937 34 I an" 4/ ATTORNEYS.

Patented June 20, 1939 UNITED STATES PATENT OFFICE GENTBJFUGAL PUMP Don Llewellyn, Huntington Park, Calif.

Application April 15, 1937, Serial No. 137,063

3 Claims.

This invention relates to rotor pumps and particularly pertains to centrifugal pumps.

In the operation of large centrifugal pumps, such as those used in irrigation and reclamation 5 projects, and in connection with certain engineering construction where it is the present practice to move sand, gravel, and dirt while associated with water, and for rapid transportation of these products, centrifugal types of pumps are used through which the water and solids are pumped. In the operation of such pumps it is obvious that the rapid movement of the "solids, which solids are often gravel and pieces of rock of irregular shape, have an abrasive action and rapidly wear away the pump particularly at its throat portions. Various attempts to build pumps which will resist this action have been made, such for example as. constructing the pumps in their entirety of special metals having 20 wear resisting qualities, and also by lining the pumps in their entirety with rubber and the like. These attempts have been unsatisfactory, however, since in the first instance the cost of lining the pumps was prohibitive and in the use 25 of an entire rubber lining, it was found that the abrasive action rapidly impaired the operation of the pump in that it was necessary to remove the entire lining if any part thereof was worn out. The present invention is concerned with 30 a pump structure of the centrifugal type in which special wear resisting elements have been applied at the throat portions of the pump and along the path of travel of the material moving therethrough, said elements acting to resist abrasion and to alleviate wear throughout the pump throat whereby the life of the pump at this point will be materially prolonged and its efilciency increased.

The present invention contemplates the provision of a pump structure including an annular pump housing within which a centrifugal rotor is mounted, said housing being equipped at its throat portions with wear surfaces.

45 in the accompanying drawing in which:

Figure l is'a view in longitudinal central section through the pump showing its details of con- The invention is illustrated by way of example struction and the points of application of the struction of the impeller mouth ring-liner and manhole section liner.

Referring more particularly to the drawing, I indicates the pump shaft provided at its outer end with a coupling flange H and at its inner end with a reduced threaded portion l2. Mounted upon the shaft III at a point intermediate its ends is an anti-friction bearing structure l3 suitably supported in a journal box l4 mounted upon a base IS. A pump of the centrifugal rotor type is associated with the shaft ill in a manml which will be hereinafter described. It is to be understood that the exact design of this pump is immaterial to thepresent invention and that the invention is more particularly concerned with the structural parts of the pump which embody the application of specially constructed wear elements at the throat of the pump, as will be hereinafter disclosed. The pump generally speaking comprises a bearing element "5 mounted upon the shaft III at a point intermediate the bearing structure l3 and a pump rotor I! which is secured on to the threaded end of the shaft I0. The rotor I1 is of the centrifugal impeller type having a back wall l8 and front wall I9 spaced with relation thereto and forming an intermediate arcuate passageway 20 leading from the circumference of the rotor to a central open- -'ing 2| of the pump casing 22 at the opposite side of the rotor from the end of the shaft I0. The rotor l'l carries a plurality of impeller blades, not illustrated, which operate in space 20 occurring between the walls l8 and I9 and act to draw fluid in through the throat 2| and discharge it through a tangential outlet in the pump casing in the usual manner. A suction or inlet conduit 23 is disposed in longitudinal alignment with the entire throat 2| of the rotor and is secured to front plate 24 of the pump casing. A

back plate 25 is provided on the casing being dis- 4o posed upon the opposite side of the rotor and in a position to circumscribe the shaft in. The front and back plates 24 and 25 are provided with circumferentially arranged sets of lugs 26 along their peripheries having openings to restricted throat 30 which occurs at the juncture of the chamber 28 with the circumference of the rotor 29. At this particular point in the travel of the liquids and solids through the rotor and into the discharge member 28 there is considerable wear due to the abrasive action of the solids carried with the liquid passing through the pump. It is also desirable at the juncture of the circumference of the rotor and the circumscribing face of the discharge chamber to create an effective fluid seal between these parts so that the tendency of the material passing through the pump would be to continue its course rather than to leak around the edges of the rotor and into the pump casing. In order to protect and effectively seal this area rubber shoulder liners have been provided. The form of shoulder liner is indicated in Fig. 2 of the drawing and is designated by the reference numeral 3|. The shoulder liner 3| comprises a steel backing ring 33 here shown as angular in cross-section, it being understood that this ring is in the form of an annulus which seats against a circumferential face 34 and an end face 35 of the wall of the discharge member 28. These faces are set in from said wall so that a circumferential shoulder 36 will occur at the end of the face 35 and a face 31 will occur at the end of the shoulder 34. The steel backing ring 33 does not completely extend to the shoulder 36 and the face 31 and the edges of its sectional elements are feathered outwardly. Vulcanized to the outer surface of the backing ring 33 is a rubber facing 38. This facing has a curved face 39 which conforms to and merges into the contour of the inher face of the discharge member 28. The member 38 is in the shape of an annulus and has an inner circumferential face formed with a fiat circumferential portion 40 and a tapered circumferential portion 4| which circumscribe the edge of the front wall H) of the rotor 29. The shoulder structure 3| is held in position by a series of set screws 42 which. extend through openings 43 in the wall of the discharge member 28 and are threaded into the ring 33 which is formed with bosses 44 to receive them. It will be evident that due to the fact that the heads of the screws 42 are accessible exteriorly of the discharge member 28 the entire structure 3| may be secured in place and compensate for wear of the facing. It is understood that one of the shoulder liners 3| is applied to each side of the throat 30 of the discharge member.

It will thus be seen that in the structures designated as shoulder liners 3| a wear resisting surface will be presented to the abrasive action of the material being forced through the pump and that due to the structure shown it will be possible to readily remove and renew such faces as required.

It will be understood that in the construction of centrifugal pumps of the type here disclosed it is not practicable to have the relatively moving faces of the rotor and the case in intimate contact with each other, since the abrasive action of the sand and water would rapidly wear away these faces and cause leakage. It is therefore usual to provide a limited amount of tolerance between these faces and to provide means also tending to move the liquid from between the outer faces of the rotor walls l8 and I9 and the front and back head liners 5| and 52 respectively. These head liners are interposed between the front plate 24 of the pump casing and the rear plate 25 of the pump casing respectively and are constructed and held in a manner to be hereinafter described. The head liners are designed to be made 'of wear resisting steel alloy. Attention is directed to the fact that the front head line 5| conforms to the contour of the front rotor wall |9 while the back head liner 52 extends in a plane at right angles to the longitudinal axis of the pump. The front head liner 5| as indicated in Fig. 1 of the drawing is shown as formed with a rubber facing 54. In each case, the liners 5| and 52 will be held in position by screws 58 which pass through the heads 24 and 25 of the motor case and secure the liners in position. Attention is directed to the fact that the rubber faces of the head liners extend upwardly and abut against the outer end faces of the shoulder liners 3| to form a tight seal therewith. As before stated, due to the tolerance between moving parts and the case, there is a tendency for water and suspended solids to pass between the surfaces of the case and the moving parts. abrasive action. In order to move the liquid which leaks in between the rotor and the head liners the outer faces of the walls l8 and 9 of the rotor are formed with ribs extending radially. The wall l8 carries a plurality of ribs I8 and the wall I9 carries a plurality of ribs I9. The ribs l8 conform along their edges to the contour of the back head liner 52 and a bearing member but are spaced therefrom as previously described. The long ribs may be cast integral with the wall of the rotor. The short ribs may be made of special wear resisting material, such as rubber, or of wear resisting steel alloy. In the latter instance the alloy is preferably Welded in place.

-When the structure is made of rubber a suitable metal backing is provided and may be secured to the wall of the rotor by fastening screws.

In the present construction the suction end of the rotor hub is designed to assume an abutting relation to the end face of the inlet conduit 23 while being slightly spaced therefrom. The contiguous faces of the rotor and the conduit are fitted with ring liners l4 and I5. These ring liners as shown in the enlarged view Fig. 3, comprise a rubber facing 16 vulcanized to a steel back plate H by which they are secured in position. Thus it will be seen that at the points or surfaces between which abrasion would occur due to the movement of relatively fine suspended solids in the liquid being pumped there are interposed elements having special wear resisting properties and that at the throat of the discharge member where the violent action would take place a throat is fitted with a shoulder .tending to resist this action.

In operation of the present invention the pump is assembled as shown with the various liners in position as indicated in Fig. 1. Attention is directed to the fact that at all of the vulnerable points where excessive wear between moving parts occurs the opposing surfaces are fitted with special wear resisting elements. In a pump of this general type the shaft Ill is driven at a relatively high rate of speed and a large amount of liquid and materials are moved through the pump. For example, the inlet conduit 23 may have a diameter of more than two feet. It will therefor be appreciated that a large volume of material will be drawn through the pump and that in this material may be associated sand, gravel, and boulders which are being moved. As these suspended and moved articles are drawn toward the periphery of the rotor 29 they will be thrown across the chamber of the discharge member 28 and their force will be to a great extent spent These solids thus produce an H which it passes into a space 8| occurring between the back wall I8 of the rotor and the head 25 of the pump casing. The force of this supplyof water tends to move the accumulated liquid and solids outwardly through this space, the said materials having seeped in .between the moving.

the liquid and material tend to form eddies which rapidly abraid pits in the surfaces so that after such abrasion has been started the efliciency of the pump is readilydecreased. Attention is directed to the fact that the rotor and its casing must fit together with a certain amount of tolerance in order to efflciently operate, and if this tolerance greatly increases due to excessive wear of the parts the efllciency of the pump rapidly drops. For example, in. a pump of the general dimensions shown in the present case having a rotor substantially six and one-half feet in diameter the tolerance between parts is approximately one-eighth of an inch, but if this space widens to as much as one-quarter of an inch the maximum efllciency of the pump is reduced. By providing the wear resisting surfaces at pointswhere adjustment of clearance is required the adjustment is more readily obtained and the efficiency of the pump is greatly prolonged without requiring the replacement of worn parts. In operation of a pump of this type as ordinarily constructed the velocity of the moving material as it passes outwardly from the space 8| between the back wall l8 of the rotor and the head 25 of the casing acts to directly cut away a large crevice inthe circumscribing face of the wall of the discharge member 28. With the special wear shoulders 3| as herein provided this wearing action is materially diminished,

It will thus be seen that the pump structure here disclosed is designed to provide a pump of I eflicient operation while at the same time fitting it .with special wear resisting elements disposed at vulnerable points between the moving parts of the apparatus, at which points the necessary adjustment of parts will be maintained while resisting the usual wear occurring, thus insuring that the pump will be maintained with its parts in adjustment for a longer period of time and that the efficient operation of the pump will thus be sustained.

While' I have shown the preferred form of my invention, as now known to me, it will be understood that various changes might be made in the combination, construction, and arrangement of parts, by those skilled in the art, without departing from the spirit of the invention as claimed.

Having thus described my invention, what I claim and desire to secure by Letters Patent is;

1. In a centrifugal pump a circular casing having an axial inlet and a circumferential outlet chamber substantially circular in cross-section and being formed with an inner circumferential opening, a rotor within said casing having spaced side walls forming a passageway communicating axially with the axial inlet and radially with the circumferential opening, the side walls of the outlet chamber overhanging the circumferences of said rotor walls and annular shoulder liners carried by the casing and interposed between the overhanging shoulder of the walls of the outlet chamber and the circumferential faces'of the rotor walls, said shoulder liners being made of rubber to resist abrasion.

2. In a centrifugal pump a circular casing having an axial inlet and a circumferential outlet chamber substantially circular in cross-section and being formed with an inner circumferential opening therearound, a rotor within said casing having spaced side walls forming a passageway communicating axially with the axial inlet and radially with the circumferential opening, the side walls of the outlet chamber overhanging the circumferences of said rotor walls, annular shoulder liners carried by the casing and inter,- posed between the overhanging shoulder of the walls of the outlet chamber and the circumferential faces of the rotor walls, said shoulder liners being made of rubber to resist abrasion and having metal backing plates therein, and' means carried by the casing to engage the backing plates and to hold the liners in position.

3. In a centrifugal pump a circular casing having an axial inlet and a circumferential outlet chamber substantially circular in cross-section and being formed with an inner circumferential opening therearound, a rotor within said casing having spaced side walls forming a passageway communicating axially with the axial inlet and radially with the circumferential opening, the side walls of the outlet chamber overhanging the circumferences of said rotor walls, annual rubber shoulder liners carried by the casing and interr posed between the overhanging shoulder of the walls of the outlet chamber and the circumferential faces of the rotor walls, said shoulder liners having a'portion interposed between the circumference of a rotor wall and the wall of the casing and a flange portion substantially at right angle thereto and being set in to the face of the wall of the chamber whereby a peripheral throat portion is provided along and through the inner circumferential opening of the'casing, a metal backing plate forming a part of said shoulder liner, said plate being angle-shaped, the separate legs of the plate extending along the two portions of the liner and fasteningmeans carried by the easing and engaging the backing plate to hold the liner in position.

DON LLEWELLYN.

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