US2228207A - Centrifugal pump - Google Patents

Description

Jan. 7, 1941. A. G. FoRssl-:LL

CENTRIFUGAL PUMP Filed Dec. 2, 1939 s sheets-sheet 1 @D o Qlilllll BY @4; www

ATToRNEYa IHIIIIi Jan. 7, 1941. A G, FORSSELL 2,228,207

GEN TR I FUGAL PUMP Filed Dec. 2, 1959 3 Sheets-Sheet 2 ATTORN EY5 Jan 7, 1941 A. G. FoRssELL 2,228,207

CENTRIFUGAL PUMP Filed Dec. 2, 1939 3 Sheets-Sheet 3 INVENTOR ATTORNEYJ,

Patented Jan. 7, 1941 PATENT oFFICE CEN TBIFUGAL PUMP Alfred G. Forssell, Baldwinsville, N. Y., assignor to Morris Machine Works, Baldwinsville, N. Y., a corporation of New York Application December 2, 1939, Serial No. 307,297

2 Claims.

y This invention relates to a centrifugal pump of the type which includes a circular casing having an axial inlet for the material to be pumped and a peripheral outlet for the same, and a ro- .tary impeller or runner arranged in the casing and adapted to suck'the material through said inlet into the casing and discharge the saine through the outlet thereof.

In pumps of this type as heretofore constructl0 ed any air contained in the liquid, sludge or the like which was being pumped would remain associated with the liquid while passing through the pump, thereby producing an irregular action due to the liquid being practically non-compresl sible while the air is compressed by the pump and expands when discharged therefrom.

In prior pumps of this character liquid could freely enter the spaces between the outer sides of the shrouds and the inner sides of the front and rear walls of the casing and thereby not only produce an unequal pressure against these walls but also interfere with securing the most uniform and eilicient operation of the pump.

The object of this invention is to provide a .25 pump of this character whereby the above mentioned dimculties are overcome by means which are simple in construction, efcient in-operation and do not appreciably increase the cost of the pump. v

In the accompanying drawings:

Fig. 1 is a side elevation of a centrifugal pump embodying these improvements.

Fig. 2 is a vertical longitudinal section, on an enlarged scale, of the casing and intake part of the pump.

Figs. 3, 4, 5 and 6 are vertical transverse sections of the pump taken on the corrpondingly numbered lines in Fig. 2.

Fig. 7 is a fragmentary longitudinal section taken on line 1 1, Fig. 5.

In the following description similar reference characters indicate like parts in the several iigl ures of the drawings:

The numeral I0 represents the main frame of the pump which may be of any suitabletconstruction, II the tank containing the liquid, sludge or like material which is to be handled and I2 a motor for driving the pump and mounted on the rear part of the main frame. 'Ihis motor in the 5o present instance is of the electric type but any other kind of prime mover may be employed. 0n its front part the main frame is provided with a standard I 3 and on this is mounted the pump which contains the present invention and which 55 is constructed as follows:

(Cl. 10S- 103) I standard and provided centrally in its front wall with an inlet eye or opening I1 through which the material to be pumped is introduced into the casing and provided on its periphery with a tangential outlet or delivery pipe I8 through which 15 this material is discharged from the casing.

The material to be pumped is conducted from the lower end of the supply tank II to the pump casing by a tubular intake or suction pipe I9 which communicates at its front or inlet end 20 with an outlet opening 20 on.the lower part of one of the tank walls while its rear or outlet end communicates with the lnletgl'l of the casing, the connection between this suction pipe and the' tank and casing being effected by bolts 2|, 22, as 25 shown in Figs. 1 and 2.

It has been found in practice that any air which may be present in the 'material being pumped produces erratic or irregular action of the pump due to successively compressing'and 30 releasing the air during its passage through the pump and for this reason it is desirable to eliminate thev air from the material on its way from the tank to the pump case. This is eiected by tapering the intake or suction pipe I9 from its 35 inlet end to its outlet end, as shown in Figs. 1 and 2 and also making this pipe of eccentric form in cross section so that theupper par-t 23 of its wall is arranged at greater distance from the axis of the casing inlet or eye I1 than the 40 lower part 24 thereof, as shown in Figs. 2 and 6. By this means a pocket 25 is formed in the upper part of the suction pipe above the casing inlet I1 into which air contained in the material to be pumped can escape as it separates from this ma- 45 terial during its passage through the suction pipe g and thereby enabling the material to enter the pump casing with no appreciable amount of air,' if any, being mixed therewith and thus avoiding the objectionable effects above mentioned.

Any air which is separated from the material to be pumped and enters the receiving pocket 25 is discharged to the outer atmosphere through a vent opening 26 in the high part of the upper u wall of the suction or intake pipe which open-'55 ing'is preferably connected with the lower end of a vent pipe 21 which has its upper end leading to the atmophere and terminating on a line with or above the top of the material supply or storage tank Il so that no material from the tank can overow through the vent pipe in the event that the level of the material should rise in the latter.'

The vent opening 26 is arranged above the top of the inlet eye I1 of the pump casing and is constantly open to the atmosphere so that air and gas bled off from the material as it passes through the suction pipe-before this air or gas reaches the pump will be collected in this pocket and conducted to the atmosphere without requiring any valves for this purpose. For convenience in cleaning the inside of the intake or removing any rubbish therefrom the same is provided on one side with a hand hole 28 which is normally closed by a cover 29 removably at tached to the intake pipe by bolts 30, as shown, or by any other appropriate means.

The impeller whereby the material is. propelled through the pump casing from the inlet to the outlet thereof is constructed as follows: The numeral 3| represents the hub o! the propellewhich is arranged centrally in the pump casingv and axially in line withthe inlet 11 of the same. This hub is secured to the front end of the driving shaft 32 whereby the impeller is rotated, this shaft extending through a stufiing box 33 on the rear wall of the pump casing and connected at its rear-end with the shaft 34 of the motor I2 whereby the pump is driven. Intermediate of its ends the impeller driving shaft 32 is journaled by means of a suitable bearing 35 on the standard I3 of the frame, as shown in Fig. 2.

The numeral 36 represents a rear or hub shroud having the form of'l an imperforate disk which extends laterally from the rear part of 'the hub and along the inner side of the rear casing wall l5 and 31 represents a front or suction. shroud of 4disk form which is arranged along the inner side of the front casing wall I4 and is provided with an eye or suction opening 38 which is axially in line with the inlet l1 of the casing and extends laterally from the eye or opening 38.

Between the shrouds a plurality of main vanes 39 are arranged which vanes are preferably of spiral or snail shape and formed integrally with the front and rea-r shrouds by casting the same of metal.

During the rotation of the impeller in the direction of the arrows in Figs. 3, 4 and 5 'the material is drawn axially from the intake pipe through the inlet Il into the casing and carried circumferentially within the casing by a main vvane 39 and then discharged through the tangential outlet of the casing to the destinationof the material.

It has been found by experience that. in the absence of any means to prevent it, some of the material which is being pumped ows backwardly into the spaces between the outer sides of the front and rear shrouds and the inner sides of the front and rear casing walls and thereby in=` 1 terferes with the working of the pump and re= duces the emciency of the same. To avoid this back flow of material the outer side of the rear shroud is provided with one or more long auxa iliary rear vanes dil, preferably two which ex= tend radially outward from the hub of the im= peller to the periphery of the rear shroud 3d and along the inner side of the rear casing wall l5, and the outer side of the front shroud is provided with one or more, preferably two, short auxiliaryfront vanes 4l which extend radially outward from the eye or opening 38 in the front shroud to the periphery thereof. The auxiliary vanes are preferably of the same snail shape as the corresponding main vanes and are arranged in the same planes as the corresponding main vanes and are also formed integrally with the shrouds and main vanes, as shown in Figs. 3-7, thereby forming a structure which is strong and durable and not liable to get out of order and can also be manufactured at low cost.

As the impeller rotates any liquid material in the spaces between the shrouds and the front and rear casing walls is thrown radially out-` ward centrifugally by the front and rear auxiliary vanes and into the material winch is propelled by the main vanes thereby preventing any dragging action on the impeller which otherwise occurs and instead enabling the latter to work with maximum eiiiciency and yield the greatest output for the amount of power consumed.

if the peripheral diameters of the front and rear shrouds were the same, the outward pres- .sure against the rear shroud would be greater than the outward pressure against the front shroud owing to the greater area of the solid rear shroud and the greater length of the rear-gio auxiliary vanes as compared with the area of the *t centrally perforated front shroud and the relatively short front auxiliary vanes, which unbalanced pressures would produce an undesirable distorting strain. on the casing. To avoid this eiect the front shroud is made of larger diameter than the rear shroud and the auxiliary vanes of the front shroud are correspondingly extended radially outwardly beyond the outer ends of the rear vanes, thereby compensatingl for the difference in area of the front and rear shrouds and causing the pressures between the shrouds and the front and rear casing walls to be uniform, or substantially so, in order to avoid the objectionable distortion mentioned. Moreover by making the suction or front shroud of larger diameter than the rear or hub shroud it is possible to increase the length of the front auxiliary vanes equivalent to the length of the main vanes and the rear auxiliary vanes and thereby provide pressures in the chambers or spaces between the shrouds and the casing which are equal to the pressure produced by the main vanes.

I claim as my invention:

l. A centrifugal pump comprising a circular casing having a horizontal inlet on its front side and a tangential outlet on its periphery, and an impeller which rotates in said casing on a horizontal axis and which includes a central hub arranged opposite said inlet, a yrear annular shroud extending laterally from said hub and arranged along the rear wall of said casing, a front shroud arranged along the front wall of the casing and having a. central opening which registers with the inlet of the casing, main vanes arranged between said shrouds, rear auxiliary vanes arranged on the outer side of the rear shroud, said rear shroud being imperforate and its auxiliary vanes extending from said hub to the periphery of this shroud, and front auxiliary vanes arranged on thevouter side of and extending from the opening in the front shroud to the periphery of the same and said front shroud being of larger-diameter than said rear shroud;

2. A centrifugal pump comprising a circular with the inlet ol the casing, main vanes arranged between said shrouds, rear auxiliary vanes arranged on the outer side of the rear shroud, and front auxiliary vanes arranged on the outer side of the front shroud and said front shroud and 5 front vanes being of larger diameter than said rear shroud and rear vanes.'

man G. r'oRssELI.

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