US2029766A - Screw feed centrifugal pump - Google Patents

Description

Feb. v4, 1936.

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Feb. 4, 1936. A. c. DUR-DIN, JR

SCREW FEED CENTRIFUGAL PUMP Filed Augf 18, 1934 2 sheets-sweet 2 INVENTOR. 7gg/fw C. wdh, J/f

BY fw K ATTORNEY.

v Patented Feb. 44, 19236 Augustus C. Durdin, Ir.: Niles Center, lll., assigner to Chicago Pump Company, Chicago. Ill., a corporation of Illinois Application'August 18, 1934, Serial No. 740,381

'I'his invention relates to screw feed centrifugal pumps and its principal object is to provide means for eliminating binding and clogging of the ump. The pump forming the ubject matter of his specification is intended priiarily for pumping liquids containing solid or semi-solid matter,

as for instance sewage, paper pulp and so forth. Ordinarily a screw conveyor and co-operating comminuting means are provided for reducing the lo solid and semi-solid matter into smaller frag4 ments before they enter the pump impeller, and

no claim is made herein to l suchl comminuting means but from experiments made in actual prac-l tice, it has been found that the solid and semila solid matter collected at various parts of the pump and formed obstructionsfor the screw conveyor and the impeller, the result being that the accumulated solid matter stopped the pump, and

it had to be taken apart frequently and cleaned.

l In accordance with the present invention, stationary cutting means are provided at the several places where .the solid4 or semi-solid`matter is likely to enter clearance spaces between the pump v casing and the rotating parts therein, which sta- 29 tionary cutting means' co-operate with cutting edges of the rotatingparts to sever or cutaway from the mass any piece that-would otherwise enter the clearance spaces and cause a binding" action between the pump casing and the rotating 30 parts'therein. By the application of the present improvements to screw feed centrlfugalvpumps, clogging and binding have been 'elminated and the pumps runfindenitely even when subjected to the most rigid tests.

tures hereinafter fully set forth and claimed.

An exempliflcatlon of the invention is illustrated in the drawings accompanying this speclflcation in which:

40 Fig. 1 is a central, vertical-longitudinal section 'through a screw feed centrifugal pump embodying the invention;

Fig. is a vertical cross section taken on `the line Fig.,3 is a detail, fragmental cross section taken on the line 3-3 of Fig. 1;

Fig. 4, isa detail, fragmental horizontalsection taken on the line 4-4 of Fig. 3; 1

50 Fig.` 5 is'a detail, fragmental, vertical section taken on the line 5-5 of Fig. 3;

Fig.' 6sis a vertical lcross section taken on the line 6.-6 of Fig.' 1;l A Fig. 7 is avertical cross Section taken on the 55 niici-icfmarana The invention consists in the several-novel fea Fig. 8 is a detail cross section taken on the line 8.- 8 of Fig'. 7. Y Referring to said drawings, the reference character I0 designates a base upon which are mounted two end brackets II, I2, containing bearing 5 `-boxes I3 in which is journaled the pump shaft I4.

Between the end brackets is the pump casing I5, which is composed of a cylindrical part I6 and a volute part I1 communicating therewith through Ianrpening in the'discharge end of the cylindrical 10 part. A suction inlet is enters through the side of the cylindrical part of the. pump casing and a dischargeoutlet I9 leads from the volute part thereof. Desirably the end brackets are formed with upright circular parts 20, 2|, that comprise l5 heads for the pump casing and are bolted thereto. and the cylindrical part of the casing is formed with a circular flange 22 which is bolted to the volute part andforms one head thereof. IIhe 'exact form of casing construction is, however, not 20 `materlal to the invention, broadly considered. On the heads 20, 2l are stuiilng boxes and the usualwaterseals 23 for preventing leakage around the pump shaft. 'I'he end brackets II, I 2 and pump casing I5, composed of the cylindrical part 25 I6 and volute part Il, being made of separate parts bolted together, the pump casing may be adjusted clrcumferentially around the axis thereof to locate the suction inlet or the discharge outlet or both, invertical or inclinedpositions instead of the horizontal positio'n illustrated.' This arrangement is of a special importance in con- -necting the pump to the pipelines since either the incoming or outgoing line orboth lines to and from the pump may be horizontal, vertical or.

' inclined. The entire casing I5,.,or either the cylindrical part IB thereof or the volute part I1. may be rotated relative to the endbrackets to locate the discharge outlet at various desired positions around the axis of the casing. 40

vMounted, on the pump shaft are a screw conveyor 24 and an impeller 25 formed separately or4 integrally as desired, the screw conveyor rotating ,i`n` the cylindrical part of the pump casing and` the impellerrotating in the volute part.

The screw conveyor has one or more helical blades 2S which join with the impeller blades 2l of the iin-v peller and serve to convey solid and semi-solid matter-to the impeller. Cooperating with the blades ofthe screw conveyor are comminutin means for cutting, breaking, tearing, shearing or otherwise eomminuting solid and semi-solidmatter that enters the'v pump, lhere shown inthe form of bars 28, that extexidlongitudinally along the internal face o f the cylindrical part of the /casf 55 ing and are seated m grooves formed 1n the mternal face and secured therein by bolts 29. The

the solids and`semi-solids and feeds the coml minuted mass t9 the impeller and the latter discharges the liquids and comminuted mass from the pump. No claim is made to the pump construction thus? far described, and I shall now proceed to describe the novel features whic comlprise the present invention. Y' One of the places where the solids or semi- /slids cause a binding effect is at the clearance conveyor and the head 20 of the cylindrical part ofthe casing. -Stringy material ordinarily becomes caught on the ends of the blades and to prevent thel accumulation of such matter with the attendant binding at this place, cutting bars 30 are let into grooves in the head 20 and secured therein by bolts 3|. A slight clearance is left between the terminal ends of the screw conveyor blades 26 and the head 20, and the cutting bars 30 project from the internal face on the head into this clearance space and co-operate with the end edges of the blades 26 to cut or shear off any stringy material or other pieces of material that lap over the end edges of the blades. The material being severed at the overlapping part, itis #readily fed forward by the screw conveyor and the Abinding action is entirely eliminated at this place.

Another place where the material is likely to X wrap around the blades lis at the place where th e of the discharge en'd of the cylindrical partici the casing (see' Fig.,5) and a cutting ring 32 is` let into the' cylinder, which ring ts tightly therein and co-operates with^therhelical blades of vthe l screw conveyor to cut or sheavol any material that may lap over said blades at the place where the blades travel along`the edge of the ring. It

is to 'be observed that a considerable portion of the mass is'carried along the internal cylindrical face of the easingby the helical blades and some moves along the side of the'comminuting bars 28. As the'ma'ss reaches the cutting ring 32' any r.material that overlaps the helical blades is cut or sheared off at the ring,pass ing on to the impeller without 'being caught around its edgeI and as`a consequence binding or clogging at this point has been eiiminatedg Another place where binding. is lightly to occur is at the clearance space between-the'impellei` blades 21 and the head 22 .of the volute i1. Stringy material and other 'material is 4likely to o nd its way -into this clearance space and cause u fsutlicilent binding to stop the pump. To prevent space between the helical blades 26 of the screw:

. impeller or both. i

material from entering this clearance space, I provide cutting bars 33 (see Figs. 3 to 5) that are let into grooves in the internal face of the head 22 and are secured therein by bolts 34. The cutting bars 33 project into the clearance space between the head and sideedges of the impeller blades and co-operate with the blades to cut or shear oi material that overlaps the blades, thereby enabling `the blades to discharge thesevered pieces along with the flowing liquids. Desirably the face of the head 22 is relieved along the cutting side of the bars 33 as at 35 to facilitate the cutting action and to provide space for the cut away pieces. The cutting bars 33 project in front of the cutting ring 32.

In the form of impellershown the blades project from a disclike wall 36, located adjacent the head 2| and narrow impeller blades 3`| similar to 'the blades 21 are provided on the side of the wall 36 opposite the blades 2l. To prevent binding in the clearance space betweenl the blades 31 and.'

`the head 2|, cutting bars 38 (see Fig. 7) similar to the cutting bars 33 are provided on the head 2|. If desired the faces of the head 2| and the head 20.may be relieved adjacent the cutting bars in the same manner as the face of the head 22 is relieved at the cutting bars 33 (see'Fig. 4). It has been found that with the ordinary throat leading-from the volute to the discharge inlet, the comminuted matter would clog the throat of small pumps. To overcome this, instead of forming a throat of circular cross section, as usual, in small pumps I have widened the throat considerably as at 40 (see Figs. 'I and 8) making a verticallyelongated opening or passage from 35 which leads an outwardly flaring throat, and iind that this change d oes not impair the efficiency of the pump in any manner, but does effectively prevent clogging in`the throat.

. By providing cutting means at the several places 4()v where solid or semi-solid material is likely to cause binding between the casing and rotating parts.

. I have provided a pump for handling liquidscontaining solid or semi-solid matter wherein thev possibility ofbinding or clogging is entirely elim- 45 inated. More specifically by providing cutting means o n all sides of the screw propeller and impeller blades that rotate in close proximity to stationary walls, I eliminate the possibility ot clogging due to the accumulation of solids between the closely spaced relatively rotatable parts. The pump is particularly adapted for pumping sewage, although its use is not limited thereto as ity is highly eillcient, for pumping liquids contain- It is also to be observed that both the screw pro- 00 peller andthe impeller propel comminuted solids.

It is to be understood therefore that the'term propelling element -as used-in theffollowing claims includes either a. screw conveyor oran [More or less variation of the exact details of construction is possibleflwithout departing from the spirit of this invention; I desire, therefore' not to limit myself to the exact form of the construction shown and described, but intend, in

. the following claims to point outfallof the inventiondisclosed herein.

' I claim as new` and desire to secure'y by Lettera Patent:

l. A pump for pumping liquids containing solids or semi-solidscomprising 'a casing having a cylindrical part and a volute -pa'rt opening thereto, some of the faces of the cylindrical and volute parts being flat, a screw conveyor rotating in the cylindrical part and an impeller rotating in the volute part, there being an inlet'in the cylindrical part of the casing adjacent the flat wall thereof, said screw conveyor and impeller thereto, some of the facesof the cylindrical and volute partsbeing flat, and there being an inlet 5 (in the cylindrical part, a screw conveyorjrotating in the cylindrical part of the casing, and an imseated in grooves in said flat faces at the inlet .and co-operating with said edge portions of the ends of the screw and impeller, and projecting into said clearance spaces and co-operating with said edge portions of the screw conveyor and impeller to shear off material that is carried to said clearance spaces.

3. Al pump for pumping liquids containing solids or semi-solids, comprising a casing having a cylindrical part and a volute part opening thereto, some of the faces of the cylindrical and volute parts being flat, and there being an inlet in the cylindrical part, a screw conveyor rotating in the cylindrical part of the casing, and an impeller rotating in the volute part, said screw conveyor and impeller having edges traveling throughout their entire extent in close proximity to the flat faces of the casing, and means for maintaining free clearance spaces between said flat faces of the casing and edges of the screw conveyor and impeller comprising cutting bars seated in grooves in said faces at the inlet end of the screw vandimpeller and projectinginto said clearance spaces screw conveyor and impeller to shear oi material that is carried to said clearance spaces, the faces of the casing being relieved in front of the cutting edges of the cutting bars.

4. A pump for pumping liquids containing -solids or semi-solids, comprising a cylindrical casing having a head and a suction inlet adjacent thereto, a screw conveyor rotating in said .casing with the end edge of its conveyor. blade traveling in close proximity to said head. and a cuttingbar on said head projecting into the clearance space between the head and the end of the conveyor blade and co-operating with said end of the blade to shear oif material that is carried to said clearance space.

5. A pump for pumping liquids containing solids or semi-solids, comprising a casing having a cylindrical part and a volute part opening thereto, the casing having a flat face joining the cylindrical part with the volute parta screw conveyor rotating in the cylindrical part of the casing and an impellerrotating in the volute part, and a cutting ring extending circumferentially about the screw conveyor and secured in the cylindrical part of the casingadjacent the flat wall of the volute part and co-operating with shearoff material carried to the cutting ring.

6. A pump for pumping liquids containing solids or semi-solids, comprising a casing having a cylindrical partl anda volute part opening theretosome of the faces of which are dat, a screw conveyor rotating in4 the cylindrical part of the casing and an impeller rotating in the volute part, a comminuting bar extending longitudinally in the cylindrical part ofthe casing and a cutting ring extending circumferentially vabout the screw conveyor and secured in said cylindrical part vof the casing adjacent a flat facebetween thecylindrical and volute parts, said cutting ring co-operating with the screw conveyor to shear off material that is'carried to the cutting ring.

7. A pump for pumping liquids containing solids or semi-solids, comprising in combination,

20 the peripheral edge of the screw conveyor to a pump casing composed of a cylindrical part and `suction inlet on the cylindrical part intermediatez its ends and a discharge outlet in the volute part. o

a screw conveyor rotating in the cylindrical part and an impeller rotating in the.volute part, the screw conveyor having blades traveling in close proximity tothe end and side wall of the cylindrical part of the casing, and the impeller having blades traveling in close proximity to the side walls of the volute part of the casing, and cutting bars on all of said casing walls, outlining the screw conveyor and impellerexcept around the periphery of the impeller, said cutting bars entering the clearance spaces between the blades and casing walls, and co-operating with said blades to prevent, solid or semi-solid matterl from collecting and binding between any of the lcasing walls and co

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