US3295456A - Pump - Google Patents

Description

Jan. 3, 1967 c. c. WARREN 3,295,456

PUMP

Filed April 12, 1965 2 SheetsSheet 1 6 Clini'on Cwar're'n JNVENTOR A4404 ck @8544 Hffys.

Jan. 3, 1967 c. c. WARREN 3,295,456

I PUMP Filed April 12, 1965 2 Sheets-Sheet 2 EFFICIENCY CAPACITY GALLONS PER MINUTE Fi g 10 v Clinl'on CWarr-en JNVENTOR United States Patent 3,295,456 PUMP Clinton C. Warren, Milwaukie, Oreg., assignor to Cornell Manufacturing Co., Milwaukie, 0reg., a corporation of Oregon Filed Apr. 12, 1965, Ser. No. 447,141 4 Claims. (Cl. 103-115) This invention relates to pumps, and more particularly to a centrifugal pump including a novel type of impeller which particularly suits the pump for pumping fluids containing a certain amount of solid matter dispersed therein. To illustrate a particular use for the pump, it may be employed to pump sewage, which material ordinarily contains solids in the form of rags, etc. which tend to cause clogging with conventional structures.

The nonclogging characteristic of the pump is an important feature thereof. The pump has further advantages, however, in that its construction is such that relatively high efficiencies are maintained over a relatively Wide capacity range. Further, advantageous head characteristics are obtainable at different pump capacities.

. Thus, a pump is contemplated constituting a highly practical answer to the pumping requirements of conventional sewage-treatment apparatus.

A general object of the invention, therefore, is to provide an improved pump including an impeller with superior nonclogging characteristics.

Another object is to provide such a pump capable of handling relatively large size solid objects, with such objects passing through the pump and not impairing its operation.

A further object is to provide a pump as described, which operates efliciently at different capacities.

According to a specific embodiment of the invention, a pump housing and impeller are provided, which impeller includes a continuous vane extending across one side of a shroud forming one end of the impeller. The vane includes a distinctly defined intermediate portion extending across the eye of the impeller which, on operation of the impeller, performs initial work on fluid flowing into the impellers eye by forcing such fluid radially outwardly. To enable solid objects of large size to travel into the eye of the impeller and thence through the pump, the vane is recessed inwardly toward the shroud where it extends across the eye of the impeller. This recess afiords clearance for such solid objects, whereby such objects after traveling into the eye of the impeller may then escape from the pump by moving laterally of the vane where it is recessed and then traveling along a side of the vane to reach a region communicating with the outlet for the pump. The inlet to the pump housing is aligned with the axis of the impeller, and is defined by a surface of frustoconical shape in the pump housing which diverges outwardly progressing toward the impeller, so that the inlet enlarges progressing toward the impeller. This surface defining the inlet comes to closest adjacency with the vane of the impeller, at regions which are spaced inwardly somewhat from opposite ends of the vane. The construction has been noted to produce a self-cleaning action in the inlet, inhibiting clogging, without substantially impairing the efliciency of the pump.

In the handling of sewage, cloth material is a principal source of concern, as such tends to become wrapped around the working surfaces of any impeller causing reduction in efficiency or even stopping operation altogether. This invention particularly features a surface forming the back of end sections of the vane described shaped so as to eliminate regions of relatively low pressure on the back of the vane sections which in prior constructions are believed to have produced adherence of the rags or other Patented Jan. 3, 1967 cloth material to the impeller. With the construction, and with the impeller operating, a flow of fluid over the impeller results tending to wash away rags and the like whereby such clear the impeller immediately. Furthermore, sharp angles are eliminated, which further promotes the smooth passage of cloth material over the impeller and through the pump.

Various other novel objects and features of the invention will become more fully apparent from the following description, to be read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevation, partly in section, of a pump constructed according to an embodiment of this invention, and showing an impeller for the pump where the housing of the pump has been removed;

FIG. 2 shows the impeller illustrated in the pump in FIG. 1, viewing the impeller from a different side;

FIG. 3 is a plan view of the impeller;

FIGS. 4, 5, 6, and 7 are cross-sectional views of the impeller, taken through the axis of the impeller, generally along the lines 4-4, 5-5, 66, and 77 in FIG. 3;

FIG. 8 is a view taken generally along the line 83 in FIG. 3, or along a curving line generally corresponding to the outline of a vane in the impeller, which shows the profile of the vane as it would if straightened out, and how the same is recessed at an intermediate portion between the ends of the vane;

FIG. 9 is a view showing the curving profile of the back of a vane section in the impeller, as such would appear in a cross-sectional view taken along a curving plane which curves around the axis of the impeller in a region midway between the center and the periphery of the impeller, as shown by the line 99 in FIG. 3; and 7 FIG. 10 is a graph showing etficiency at different capacities in a typical pump constructed as contemplated.

Referring now to the drawings, and first of all more particularly to FIG. 1, the pump of the invention is shown generally at 10. The pump comprises a pump housing 12, with casing portion 14 defining a volute chamber 16 receiving an impeller shown at 18.

Closing off the top of pump housing 12 is a backside plate 20 secured to the housing by fasteners 22. Means such as a gasket (not shown) is interposed between the backside plate and the pump housing to seal the two together. Mounted on the backside plate and extending upwardly therefrom is a frame 24, which may be used to support the motor (not shown) that drives the pump, and suitable support structure (also not shown) for a shaft 26 connecting the motor and impeller 18.

Housing 12 includes adjacent the base thereof a skirt portion 28 bounded around the inside thereof by a frustoconical surface 30 defining an inlet to the pump housing. The inlet is aligned with the axis of the impeller. Fluid being handled is delivered to this inlet by a pipe such as the one partially illustrated at 32 which may be fastened to the base of skirt portion 28 as by fasteners 34. Fluid pumped is discharged from the pump housing through an outlet or discharge opening 36 communicating with the interior of the pump housing and the volute chamber 16 defined thereby.

As indicated above, distinguishing the pump of the invention is its ability to handle fluid containing large sized objects with such objects afforded a passage through the pump, and its ability to handle fluid containing cloth material such as rags and the like with such material passing freely through the pump without tending to wrap Impeller 18, in general terms, comprises a shroud portion or shroud 38 of substantially circular outline, and projecting out from the backside of the shroud a hub portion or hub 40. The shroud and hub form one end of the impeller. Extending across the front side of shroud 38, and forming the other end of the impeller, is a continuous vane 42, having a generally S-shaped outline, as can be seen from viewing the front end of the impeller as shown in FIG. 3. Ends of the vane are adjacent diametrically opposite margins of the shroud in the embodiment illustrated, as seen in FIG. 3, and because of the S-shaped outline, the vane curves arcuately in one direction, extending from a marginal portion of the shroud inwardly toward the axis of the impeller, and thence arcuately in the opposite direction, progressing from the axis of the impeller to an opposite marginal portion of the shroud. The impeller may be prepared as a casting, with the shroud, hub and vane all an integral part of the casting.

Portion 42a of the vane, located intermediate the ends of the vane at the eye of the impeller, i.e., at the front end of the impeller where the axis of the impeller is located, which is the part of the impeller first receiving fluid on operation of the pump, is clearly defined by opposed walls 44, 45 extending in an axial direction outwardly from the shroud. Withthis construction,

fluid flowing into the eye of the impeller is worked upon immediately by the vane, and caused to be urged radially outwardly toward the margins of the impeller.

Vane 42 has an edge-48 forming an outer margin of the vane along its length. As best shown in FIGS. 1 and 8, this edge is recessed, at 48a axially inwardly and toward the shroud along the intermediate portion of the vane which is located at the eye of the impeller. The length of this recessed portion is indicated by the dimension A in FIG. 3. Outwardly of this recessed portion edge 48 defines shoulders 50, 52 formed in the vane. Opposite ends of edge 48 incline at a slight angle toward the shroud (typically an angle ranging from 5 to 20 degrees isinvolved).

Surface defining the inlet for the pump diverges outwardly progressing toward the impeller, as illustrated in FIG. 1. In a typical pump, the angle of divergence may be in the range of 25-35 degrees. The surface comes to closest adjacency with vane 42 of the impeller, at regions on the vane indicated at x and y in FIG. 1. These regions it will be noted are inwardly somewhat from the ends of the vane. The clearance at these regions of closest adjacency preferably is no more than about /8 inch, such clearance assuring that maximum efliciency is obtained in the pump.

Progressing from one marginal portion of the shroud to the axis of the impeller, the vane may be thought of as comprising a vane section 42A, and progressing from the axis of the impeller to an opposite marginal portion of the shroud, the vane may be thought of as comprising another vane section 42B. The impeller inoperation is rotated in the direction of the arrow in FIG. 3 and thus it is the convex sides of the vane sections, when viewing an end view of the impeller as in FIG. 3, that are the lead sides of the vane sections and that move against fluid to work on the fluid by forcing the fluid radially outwardly on the impeller. As perhaps best illustrated by comparing FIGS. 2 and 7, the lead sides of the vanes while curving convexly when viewed from the end of the impeller, to produce arcuate outlines for the vane sections, are substantially straight and lie at a steep angle relative to the shroud viewing cross sections of the impeller taken through the axis of the impeller. In the specific embodiment of the invention illustrated, the lead sides extend at approximately 90 degrees relative to the plane of the shroud in such a cross-sectional view.

The trailing sides of the vane sections, i.e., the sides defining a concave curvature on viewing the end of the impeller, are defined by walls having curved outlines viewing cross sections of the vane sections taken through the axis of the impeller, as seen in FIGS. 4 through 7.

The wall defining the trailing side of a vane section also has an outline which curves in a concave continuous.

sweep, when viewed in a cross-sectional view taken along a line such as that shown at 9-9 in FIG. 3 (FIG. 9 is such a cross-sectional view). Along the circumferential margin of the impeller, the trailing side of a vane section is bounded by a wall 60 (best seen in FIGS. 1 and 2) which. is a smoothcontinuation of the edge of shroud 38. The wall defining the trailing side of a vane extends over approximately one-quarter of the front side of the shroud, as is well illustrated in FIG. 3 where points P and P indicate the expanse of this wall along the circumferential margin of the impeller.

Explaining now the operation of the pump, and how the impeller with its vane operates, the impeller as already indicated is rotated in the direction of the arrow, or in a counterclockwise direction, when the front of the impeller is viewed as shown in FIG. 3. The lead side of each vane section moves squarely into fluid drawn into the eye of the impeller, immediately forcing this fluid radially outwardly, whence it is further forced off the outer end of the vane section into the volute chamber in which the impeller is mounted. A swirl of fluid is produced in the volute chamber, such fluid moving when swirling at a somewhat slower speed than the speed at which the impeller is rotating.

Because of the recessed portion described at the intermediate portion of the vane, in the event a large solid object should be carried with entering fluid into the eye of the impeller, this object is enabled by the recess first to move axially inwardly on the impeller a predetermined distance, then laterally of the vane at the eye of the impeller, whence the object travels into the space existing between the trailing side of one vane section and the lead sideof the vane section directly behind. The object is then thrown by the impeller into the volute chamber which surrounds the impeller. axially inward movement, when the object moves radially outwardly on the impeller, it clears the pump housing.

In the event a cloth or like material flows into the pump, such cloth may also travel into the eye of the impeller, whence it may travel along the backside of a vane section to move against the lead side of a vane section behind, finally to be thrown off into the volute charnber of the pump housing. With the curved trailing sides of the vane sections, fluid flows as a stream over the trailing side of a vane section, and functions to wash continuously the trailing side thus to keep the cloth from sticking on the vane section. The curved shape of the trailing side of a vane section eliminates relatively low pressure regions directly behind the vane section, which in prior-known constructions have tended to cause cloth material to be pulled behind a vane and thence held there, with impairment of pump operation.

Referring to FIG. 1, because of the slope of the surface forming the inlet for the pump, on operating of the pump a circulation as indicated by the arrow 64 is promoted in side regions of the inlet adjacent the moving impeller. Fluid drawn into the eye of the impeller and not escaping into the volute chamber and the pump discharge opening tends to return along a side of the inlet and promote such circulation. This has been found to be helpful in inhibiting clogging, as the circulation results in a self-clearing action.

With the pump of the invention, good efliciencies resuit over a relatively wide range of pumping capacities (i.e., at diflerent pumping rates). In FIG. 10 the efliciency of a typical 4 inch pump constructed according to this invention is shown plotted against capacity, in gallons per minute, and it will be noted that an efficiency of 40% or better was demonstrated for capacities ranging from about gallons per minute to in excess of 750 gallons per minute.

Because of the initial.

The impeller is attached to shaft 26 by means of a fastener 66 extending through a bore 68 provided in the axis of the impeller. The usual key (not shown) keys the shaft and the impeller for movement together. Bore 68 communicates with a counterbore 72 which enables the head of the fastener to be set in somewhat from the front end of the impeller. Preferably the counterbore is filled in over the head of the fastener, as at 74, to make the edge of the vane completely smooth where it progresses across the eye of the impeller, a further feature serving to inhibit any clogging tendency in the pump.

While an embodiment of the invention has been described, it is appreciated that variations and modifications are possible without departing from the invention. It is desired to cover all such variations as would be apparent to one skilled in the art, and that come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent: 1. An impeller fora centrifugal pump comprising a substantially circular shroud adapted to be rotated about its axis and a continuous vane extending across one side of the shroud forming one end of the impeller which vane, when viewing said one end of the impeller, includes one section that starts at a marginal portion of the shroud and thence in outline arcuately curves in one direction progressing toward the axis of the impeller, and another section joined to said one section at the axis of the impeller which in outline arcuately curves in the opposite direction progressing from the axis of the impeller toward another marginal portion of the shroud which is spaced circumferentially on the throud from said first-mentioned marginal portion,

that side of each vane section which is the convex side, on viewing said one end of the impeller, forming the lead side of the vane section on operation of the impeller which moves into fluid to work thereon, and such convex side being defined by a wall that curves when viewing the impeller from its said one end to produce the arcuate outline for the vane section, but which is substantially straight and lies at a steep angle relative to the shroud viewing cross sections of the impeller taken through the axis of the impeller,

that side of each vane section which is the concave side, on viewing said one end of the impeller, forming the trailing side of the vane section on operation of the impeller, and such concave side being defined by a wall that curves when viewing the impeller from its said one end to produce the arcuate outline for the vane section, said wall also curving concavely in cross-sectional views of the impeller taken through the axis of the impeller, and further curving in a concave continuous sweep progressing rearwardly of the vane section from adjacent the lead side of the impeller in a cross-sectional view of the impeller taken along a line that curves around the axis of the impeller.

2. The impeller of claim 1, wherein an edge forms the outer margin of the vane along its length, and this edge is recessed toward the shroud where the vane extends across the axis of the impeller thus to allow clearance for an object moving against said vane at the eye of the impeller.

3. The impeller of claim 1, wherein the convex side of each vane section is defined by a wall which is substantially at right angles to the shroud, in cross-sectional views of the impeller taken through the axis of the impeller, and wherein the wall which defines the trailing side of each vane section extends over approximately a quarter of said side of the shroud.

4. An impeller for a centrifugal pump comprising a substantially circular shroud adapted to be rotated about its axis and vane structure extending across one side of the shroud forming one end of the impeller, said vane structure including one section that starts at a marginal portion of the shroud and thence progresses toward the axis of the impeller and another section substantially meeting with the one section at the axis of the impeller which progresses from said axis toward another marginal portion of the shroud spaced circumferentially on the shroud from the first-mentioned marginal portion,

each vane section having one side which forms the lead side of the vane section on operation of the impeller, which lead side moves into fluid to work thereon, such lead side being defined by a wall which, when viewing cross sections of the impeller taken through the axis of the impeller is substantially straight and lies at a steep angle relative to the shroud,

each vane section including a side opposite the lead side which is the trailing side of the vane section on operation of the impeller, and such trailing side being defined by a wall that curves concavely in cross-sectional views of the impeller taken through the axis of the impeller, such wall also extending in a sloping sweep progressing rearwardly of the vane section from adjacent the lead side of the impeller in a cross-sectional view of the impeller taken along a line that curves around the axis of the impeller, which sweep generally extends at a shallower angle relative to the shroud than the steep angle of the wall for the lead side of the vane section.

References Cited by the Examiner UNITED STATES PATENTS 1,849,127 3/1932 Wood 103115 2,438,442 3/ 1948 Holt 1031l5 3,130,679 4/ 1964 Sence 1031 15 DONLEY J. STOCKING, Primary Examiner.

HENRY F. RADUAZO, Examiner.

Claims (1)

1. AN IMPELLER FOR A CENTRIFUGAL PUMP COMPRISING A SUBSTANTIALLY CIRCULAR SHROUD ADAPTED TO BE ROTATED ABOUT ITS AXIS AND A CONTINUOUS VANE EXTENDING ACROSS ONE SIDE OF THE SHROUD FORMING ONE END OF THE IMPELLER WHICH VANE, WHEN VIEWING SAID ONE END OF THE IMPELLER, INCLUDES ONE SECTION THAT STARTS AT A MARGINAL PORTION OF THE SHROUD AND THENCE IN OUTLINE ARCUATELY CURVES IN ONE DIRECTION PROGRESSING TOWARD THE AXIS OF THE IMPELLER, AND ANOTHER SECTION JOINED TO SAID ONE SECTION AT THE AXIS OF THE IMPELLER WHICH IN OUTLINE ARCUATELY CURVES IN THE OPPOSITE DIRECTION PROGRESSING FROM THE AXIS OF THE IMPELLER TOWARD ANOTHER MARGINAL PORTION OF THE SHROUD WHICH IS SPACED CIRCUMFERENTIALLY ON THE THROUD FROM SAID FIRST-MENTIONED MARGINAL PORTION, THAT SIDE OF EACH VANE SECTION WHICH IS THE CONVEX SIDE, ON VIEWING SAID ONE END OF THE IMPELLER, FORMING THE LEAD SIDE OF THE VANE SECTION ON OPERATION OF THE IMPELLER WHICH MOVES INTO FLUID TO WORK THEREON, AND SUCH CONVEX SIDE BEING DEFINED BY A WALL THAT CURVES WHEN VIEWING THE IMPELLER FROM ITS SAID ONE END TO PRODUCE THE ARCUATE OUTLINE FOR THE VANE SECTION, BUT WHICH IS SUBSTANTIALLY STRAIGHT AND LIES AT A STEEP ANGLE RELATIVE TO THE SHROUD VIEWING CROSS SECTIONS OF THE IMPELLER TAKEN THROUGH THE AXIS OF THE IMPELLER, THAT SIDE OF EACH VANE SECTION WHICH IS THE CONCAVE SIDE, ON VIEWING SAID ONE END OF THE IMPELLER, FORMING THE TRAILING SIDE OF THE VANE SECTION ON OPERATION OF THE IMPELLER, AND SUCH CONCAVE SIDE BEING DEFINED BY A WALL THAT CURVES WHEN VIEWING THE IMPELLER FROM ITS SAID ONE END TO PRODUCE THE ARCUATE OUTLINE FOR THE VANE SECTION, SAID WALL ALSO CURVING CONCAVELY IN CROSS-SECTIONAL VIEWS OF THE IMPELLER TAKEN THROUGH THE AXIS OF THE IMPELLER, AND FURTHER CURVING IN A CONCAVE CONTINUOUS SWEEP PROGRESSING REARWARDLY OF THE VANE SECTION FROM ADJACENT THE LEAD SIDE OF THE IMPELLER IN A CROSS-SECTIONAL VIEW OF THE IMPELLER TAKEN ALONG A LINE THAT CURVES AROUND THE AXIS OF THE IMPELLER.

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