CA1272414A - Vaneless centrifugal pump - Google Patents

Abstract

ABSTRACT OF DISCLOSURE

A centrifugal pump utilizing laminar action induced by a vaneless impeller and having a minimal drag front plate which cooperates with the circular rotor. The smooth surface of the concave face of the circular rotor has no protrusions or vanes and approximates an Archimedian curve. Material entering the intake port of the front plate is diverted about the rotating impeller and redirected in an outwardly direction along the minimal drag interior surface of the front plate to the discharge port of the output housing. The narrowing of the interior surface of the front plate in a radially outward direction with respect to the concave face of the impeller helps the pump to maintain a constant volumetric flow rate. Inasmuch as the "redirecting" of the incoming material stream follows an approximate Archimedian spiral, the pressures applied against the impeller and the forces acting centrifugally on the material stream join to produce the optimum imparting of kinetic energy to the material stream for the particular impeller speed.
As a slurries pump, the vaneless design permits any particulate size that can clear the discharge port of the pump to safely transit through the pump without maceration or undue agitation. As cavitation is totally absent, the pump can easily handle the movement of fragile, volatile or gaseous materials and can be operated over a wide range of speeds, matching desired feed without undue loss of efficiency. Lacking vanes, the impeller offers very low starting torque under a loaded condition.

Description

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BA~KGROUND OF TH~ INVENTION
l) Field of Invention:
This invention relates to centrifugal pumps for moving fluids or slurries of varying viscosities. In particular, i~ relates to such pumps having impellers which by laminar action or friction induced movement to the contained medium in the similar manner that movement of a fluid through a stationary pipe is restricted by the friction of the pipe.
~) Description of the Prior ~rt:
Most impellers for centrifugal pumps have some type of vane to impart movement to the contained fluid or slurry through the pump. These vane-type impellers have limited life because of the problem of cavitation which is the gradual deterioration or erosion of the surfaces of the vanes over time due to the movement of the materials in and around the vanes, creating poc~ets of vapor which explode causing damage. In addition, the typical vane-type impeller offers a very high starting torque under loaded conditions. Also, many pumps designed for the movement of high viscosity slurries are lîmited as to the particulate size that can be safely transited through the pump without unduly eroding the pump parts. Because of these problems, most pump parts must be manufactured of highly durable, and therefore expensive, materials. ~lso such pumps have relatively high operating costs. The impeller of the instant invention has no such material restriction (it could be made oE plastic), has lower operating costs and can move any slurry that will clear the discharge port.
One oE the earlier "Rotary Pumps" is typified by the patent of Trouve and Bellot (1900) in which the impeller was two conoidal shells rectilinear generatrixes which may be convergent, divergent or curvilinear and connected by rectlinear or helical ribs. There were a number of ~'~ 7~ 4~

1 attempts in later years to improve the efficiency of impellers. Denys, in L946, designed a disc of concave-convex profile, a disc of uniform streng~h, in which the stress at any point between the center and the rim was constant. His operating principle was that lighter molecular weight gases impinge more frequently on the rotating disk from left to right. The tangential component of rotation propels heavier molecules ~owards the outer periphery from where they are scavenged;
lighter gas molecules are scavenged from the central outlet. Later Grantham (1951) developed a centrifugal pump in which the impeller (frusto-conical) had a conical liquid-engaging surface with spiral grooves cut therein.
Pumping space was adjustable to vary the volume of liquid pumped. A modification of the invention had a multi-cone impeller.
Perhaps the closest prior art to the present invention is found in the pumps of Kletschka et al (1975) which were capable of use as heart pumps and blood pumps.
Circular fluid rotators (accelerators) were outwardly convergent and rotated to impel the fluid circularly at substantially the speed of the rotators. Angular velocity of the rotator increased as the radial distance from the axis increased. The pumping action was radially increasing pressure gradient pumping or more specifically, it was constrained force-vorte~ radially increasing pressure gradient pumping. The rotators were of hollow frusto-conical form, convergent at the peripherals. These same inventors designed similar devices, apparently with the primary objective of developing apparatus for use with delicate fluids.
Less specific prior art is found in the "turbine" of Glass (1977) which is a multi-disk plate turbine reminiscent of Tesla. The turbine had tangential nozzle delivery to peripheral portions of the plates to impart motion. Discharge was through the center. Spiral like fencing was ~ound between adjacent plates.

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Re~ent tanqential a~t kno~n to these lnventors is the patent of Her~t et al (1980) which pump was designed for reduclng cavitation-induc~d erosion of centrifugal pumps. A coni~al or stepped intake diffuser directs flow of part load edd~ from impeller back into intake fluld pulse flow~ Downstream portion of the diffuser constitutes an integr~l part of the impeller. The present invention is designed to overcome the dra~1backs of prior art impellers that are subject to cavitation and to solve oth~r problems associated ~7ith centrifugal pumps designed primarily for pumping slurries.
Prior art known to these inventors includes the follo~ing United States Patent Numbers:
651,400 6/1900 Trouve & Bellot

2,392,124 1/1946 Denys 2,569,563 10/1951 Grantham 2,977,042 3/1961 Jassniker

3,864,055 2/1975 Kletschka et al.
3,957,389 5/1976 Rafferty et al.
3,970,408 7/1976 Raf~erty et al.
204,036,584 7/1977 Glass

4,037,984 7/1977 Rafferty et a:L.
4,239,453 12/1980 Herclt et al.

The present invention is a vaneless centrifugal pump designed to overcome cavitation and the maceration found ln conventional centrifugal pumps by utllizing design principles derived from aerodynam.ics. The present invention provides a ~'~7~4~

vaneless centrifugal pump comurisincJ a :Eront plate havincl a central inlet port, a back plate, ancl a peripheral output housing and discharge port; a circular rotor to impart laminar movement to fluid material being pumped thereby, the rotor having a concave pumping face opposed to an interior surface of the front plate about the inlet port to form a pumping chamber therebetween. the width of which decreases with increasing radius such that the effective cross-section of the ~low channel is substantially constant, and the concave face of the rotor being shaped such that fluid material passing thereagainst is deviated by an angle of more than 90 degrees from its axial direction through ~he inlet port; the surfaces forming the flow channel from the inlet port throuqh the pumping chamber to the outlet housing being smooth and uninterrupted, so as to maintain laminar flow through the pump.
In a preferred embodiment the impeller of the present invention is a circular rotor that has a concave face configured from the center of the circular rotor to the outer perimeter of the circular rotor. The surface of the circular rotor is very smooth. The circular rotor is fastened to a shaft which is supported by a back plate. The back plate means ls a back plate configured to support the circular rotor and has a profile conformlng to the profile of the rear surface of the circu:Lar rotor~ permltting the circular rotor to nestle inside the back plate yet providing the necessary clearance between the circular rotor and the baclc plate. The back plate has an openlng to receive the shaft mounted therethrouyh and to support the sealing housing containinq the seal which surrounds the shaft. The back plate is coupled to a power frame or to an electrlc motor b~ means of an lnterconllectillg frame adapter. Beyond the fralne aclapter the shaft is mechanically connected to a driving motor.
A front plate is provided which, in conjunckion with a back plate and impeller, forms a pumpin~ chamber. The front plate and back plate means are attached together by mounting flanges, capscrews and nuts, providing a water tight seal. The front plate has an input port and provides an output housing and discharge port. The front plate has a smooth interior surface configured to present minimal drag to the movement o~ materials pumped therethrough. The output housing joins the ~ront plate at the discharge port and the upper end of the output hous.ing connects to an output distribution s~stem. The interior surface of the front plake contributes to the efficiency of the vaneless centrifugal pump by the configuration of the interior surface, in accordance with the principles of the present invention, to present minimal drag to the movement of materials, such as fluids and slurries, passing by the lnterior surface on the way through the pumping chamber to the dischar~e port during the pumpiny operation.
The shape of the circular rotor is such as to provide a concave annular surface the curvature of whlch gradually decreases as seen in radial section go.ing outwardly from the center. This is because the centrifugal force on the inflowing material increases towards the periphery. The front plate i.s carefully shaped relative to the profile of the circular rotor. The a~ial space between the front plate and the circular rotor decreases outwardly so that the effective cross-section is substantially ` B~

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constant ~rom the lnput port to the discharge port of the front plate. ~lore precisely, the vaneless centrifugal pump provides for a constant volulnetric flow right through the pump.
Ma~erial entering -the intake port of the front plate is diverted about the rotating impeller and redirected in an outward direction along the minimal drag lnterior surface of the front plate to the dischar~e port and the adjacent output housing. The incominy material stream follows an approximate Archimedian spiral as seen axially of the fixed plate, due to the fact that laminar flow is induced within the pumping chamber with substantially no cavitation whatsoever. The pressure applied against the impeller and the forces acting centrifugally on the material stream, join to produce the optimum imparting of kinetic energy to the material stream for the particular impeller speed.
As a slurry pump, the vaneless design permits any particulate size of material whlch can clear the dlscharge port of the pump to safely transit the pump without maceration or undue agitation. As cavitation is totally absent, the pump can easily handle the movement of fragile, volatile or yaseous materials.
Lackiny cavitation, the pump can be operated over a wide range of 5a ~$

- -1 speeds, matching desired feed without undue loss of eEficiency. Lacking vanes, the impeller ofEers very low starting torque ~mder a loaded condition and ~hus obv~ous savings in operating and maintenance costs. The varlable delivery of the pump and its ability to handle slurries of various densitiies, withou~ ca~itation, presents a significant advance in the art.
OBJECTIVES OF THE INVENTION
The objectives of the present in~ention are to provide a vaneless centrifugal pump for pumping fluids or slurries which is 1) not subject to the cavitation or agita~ion found in conventional centrifugal pumps;
2) more simple and inexpensive to manufacture than pumps known in the prior art designed to perform the same function;
3) compact in size and unitary in design to permit less costly installation and maintenance;
4) more efficient to operate, presenting lower starting torque under loaded conditions.
Other objectives and advantages of the present invention will be apparent during the course of the following detailed description.
BRIEF DESCRIPTION OF DRAWINGS
FIGURE 1 is a perspective view from the front of a Vaneless Centrifugal Pump, constructed in accordance with the principles of the present invention, showing the front plate means and the output housing. FIGURE 2 is a fragmentary side sectional view of the Vaneless Centrifugal Pump of the present invention, taken along line 2-2. of Figure 1, looking in the direction of the arrows, showing the front plate means, the back plate means, impeller means and the design of the pumping chamber formed by the concave face of the impeller means and the interior surface of the front plate means.

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1 FIGURE 3 is a perspective view from the left front of the impeller, constructed in accordance with the principles of the present invention, showing the concave face of the impeller which concave face is configured from its center to îts outer perimeter to approximate an Archimedian curve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
OF THE INVENTION

The Vaneless Centrifugal Pump is a compact, relatively - small unit, which is easily and quickly installed at a site where the pumping of fluids or sl~lrries is desired.
Throughout the following detailed description of the present invention like reference numerals are used to denote like parts disclosed in the accompanying drawings, FIGVRES 1-3. As shown in FIGURES 1, 2 and 3, the Vaneless Centrifugal Pump has a circular shaped housing, indicated generally at reference numeral 10, composed of front plate means 11 and back plate means, indicated generally by reference numeral 12, which are held together by mounting flange 13 along the outer perimeter of front plate means 11 and mounting flange 14 about the outer perimeter of back plate means 12. Mounting flange 13 and mounting flange 14 are secured to one another by cap screws 15 and nuts 16. Optionally, mounting Elange 13 and mounting flange 14 could be secured to one another by cap screws 15 and retaining threads (not shown) tapped into either of said mounting flanges. Extending upwardly from the right side of Eront plate means 11, as an integral part thereof, is output housing 17 which in turn fastens at its upper end to an output distribution system, not shown. Output housing 17 communicates with front plate means 11 through discharge port, indicated generally by reference numeral 18, located at the juncture of front plate means 11 and output housing 17.

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1 Back plate means 12 is a backplate for mounting the circular rotor of impeller means 30 thereon and has a profile conforming to the profile of the rear surface of the circuLar rotor of impeller means 30. Backplate means 12 has a vertical center portion 19 and ex~ension portion 20 which flares inwardly, at approximately 35 degrees to the vertical, to join front plate means 11 at mounting flange 13 and mounting flange 1~. At the center of back plate means 12, an opening 21 is provided to receive shaft 22 and shaft sleeve 23. Shaft sleeve 23 is surrounded by seal 24 which is held in place and kept moist by seal housing 25, thus providing a waterproof juncture. Shaft 22 is secured to impeller means 30 by key 26.
Back plate means 12 is connected to power frame 27 by frame adapter 28 which bolts to center portion 19 of back plate means 12 by a plurality of mounting cap screws 29 spaced and tapped at equal intervals around the periphery of center portion 19 of back plate means 12. Shaft 22 is mechanically con~ected to a suitable driving motor, not shown.
Impeller means, indicated generally by reference numeral 30, is a circular rotor to impart laminar movement to materials being pumped thereby and is configured to approximate an Archimedian curve. Impeller means 30 has a concave face 31 whose smooth surface is configured, from center 32 to outer perimeter 33, to approximate an Archimedian curve as shown in FIGURES 2 and 3. Rear surface 3~ of impeller means 30 is shaped to conform to the dimensions of, and the enclosure formed by, center portion 19 and extension portion 20 of back plate means 12. Impeller means 30 is faste~ed to shaft 22 by capscrew 35, threaded into the end of shaft 22 and by key 26. Nose piece 36 is threaded or snapped onto center 32 of impeller means 30 to cover the attachment means just described and to preserve the Archimedian curve of concave face 31.

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1 The front plate of front plate means 11, in conjunction with the backplate of bac~plate means 12 and the circular rotor of impeller means 30, forms a pumping chamber 39. Front plate means 11 is a front plate having input port 37, output housing 17 and discharge port 18, which front plate has interior surface 38 configured to present minimal drag to the movement of materials pumped therethrough. Front plate means 11 has input port 37, to access concave face 31 of impeller means 30, designed and positioned to direct the incoming fluids or slurries, in and around center 32 of impeller means 30, striking the smooth surface of concav2 face 31 as impeller means 30 rotates, inducing the laminar action effect observed in the art in stationary conduits. The combined forces, from the friction effect of rotating impeller means 30 and the centrifugal action of the moving material, accelerates the material rapidly, but smoothly, to discharge port 18 of output housing 17 and thence on into the output distribution system, not shown. Interior surface 38 of front plate means 11 is configured, in cooperation with the Archimedian curve of impeller means 30, to present minimal pressure, and thus minimal drag, to the movement of the fluid or slurry as these materials move through pumping chamber, shown generally by reference numeral 39, to discharge port 18. Interior surface 38 presents this minimal drag by narrowing in a radially outward direction with respect to concave ~ace 31 of the circular rotor, to maintain the volume, and thus constant pressure, of the inflowing materials, and by directing the movement of the inflowing material in a streamline, the chord of which streamline is parallel to the chord of the Archimedian spiral described by the inflowing material on the circular rotor.

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1 As best illustrated by FIGURE 2, the material stream to be pumped enters the pump of the present invention through input port 37 where the stream stri~es concave face 31 of impeller means 30 at approximately a right angle to the plane of impeller means 30. As impeller means 30 rotates, the material stream is redirected by the friction effect of spinning impeller means 30 outwardly towards the outer perimeter of impeller means 30 setting up laminar action along concave face 31 and increasing the angular velocity of the stream as i~ is diverted to the outer perimeter of impeller means 30 through pumping chamber 3g to discharge port 18. Interior surface 38 of front plate means 11 is configured to present minimal pressure, and thus minimal drag, to the material stream as it is redirected by impeller means 30.
The combination of the design of concave face 31 (Archimedian curve) of impeller means 30 and the minimal pressure, minimal drag configuration of interior surface 38 of front plate means 11, together provide an environment in which laminar flow is set up, contrary to the situation in known pumps. Such non-turbulent fluid flow with a low Reynolds number is found to provide an optimum efficient environment for pumping materials of nearly all types, including slurries which have high viscosities. The absence of the usual gaseous bubbles generated by vane-type centrifugal pumps, overcomes the problem of cavitation which is the gradual deterioration of the vanes, usually accompanied by a rattling noise and vibration of the pumping mechanisms. The absence of the vanes also permits the pumping of material of any particulate size, without maceration or undue agitation, which will clear discharge port 18 of the Vaneless Centrifugal Pump of the present invention. The absence of cavitation also permits the use of less expensive materials for casting impeller means 30, such as plastic, whereas vane-type impellers are normally constructed of ~;~72~4 l highly durable metals to combat cavitation. OE course, vane-type impellers are by design more complicated and thus more expensive to manufacture than impeller means 30 of the present invention. Being more complicated, centrifugal pumps ha~ing vane-type impellers are necessarily more expensive to manufacture and more difficult to balance than the Vaneless Centrifugal Pump of the present invention.
Impeller means 30, by its configuration having a reverse surface plane greater than 90 degrees to the - horizontal axis of the inflowing material, automatically is exercising boundary layer control similar to that observed in aerodynamics. The shape of impeller means 30 controls the pressure by establishing a predetermined pa~h for the material being pumped. The control is automatic because the pumped material follows the point of least pressure across concave face 31 which is the path of least resistance. Graphically the material is describing a streamline in the shape of an Archimedian spiral across concave face 31 as impeller means 30 rotates, said streamline being similar to the upper surface of an aircraft wing.
The curvature of interior surface 38 of front plate means 11 is designed to complement and not to interfere with the laminar induced movement of the material as it heads for discharge port 18. Trial and error observations during development by these inventors has established minimal drag to be evident when the chord of the Archimedian spiral described on impeller means 30 is exactly parallel with the chord of the streamline described by the movement of the pumped material along interior surface 38 of front plate means 11 between reference point 37 (input port) and point 11, where front plate means 11 joins back plate means 12. This minimal drag appears to be achieved when pumping chamber 39 provides for a constant volumetric rate of flow through ~v~ 7~ ~4 1 the vaneless centrifugal pump, and interior surface 38 of front plate means 11 is shaped so as to produce this effect. It should also be noted that the cross-sectional areas of input por~ 37 and discharge port 18 will be the same as each other and as ~he effective annualar cross-section through pumping chamber 39. The precise shape of discharge port 18 may not be that important provided it is smooth and does not upset the laminar flow through the vaneless centrifugal pump.
The efficient design of ~he present invention reduces opexating costs by requiring less torque to start the driving motors under load conditions. Also there are no vanes to clog or present obstructions to the free flow of the material being pumped, thus minimizing wear and tear on the pump and reducing maintenance costs. Although the Archimedian curve shown in the accompanying drawings is the preferred embodiment, these inventors claim a circular rotor, to impart laminar movement to materials being pumped thereby, having a concave face 31, configured to approximate an Archimedian curve ranging at an angle from 91 degrees to 135 degrees in relation to the horizontal axis of the inflowing materials pumped there- through.
The manufacture of impellers and centrifugal pumps is well known in the art. The variables are the viscosi~y and specific gravity of the material being pumped, the RPM (revolutions per minute) of the pump motor, and the te~perature of the pumped material. Impellers can be molded or turned on a lathe as was done in fabricating the instant invention. The preferred embodiment of the Vaneless Centrifugal Pump of the present invention, shown in the drawings, could be manufactured by merely templating the curvatures of the impeller means 30, the front plate means 11 and the back plate means 12, as shown, or as would show on a proportional enlargement of the drawings.

~X 7~ 4 l Pa~er E~am~le 1 With the valve of the present invention wide open there would be 2~.2 feet of head = 131.5 gallons per minute at 3551 RPM. The pump is a 2 x 3 pump (2 inch discharge and 3 i~ch suction line). Closing the valve results in 0 gallons per minute = 71.4 feet of head at 3556 RPM with a motor rating of 3750 RPM. As the valve of the pr~sent invention was closed the head pressure increased from 29.2 feet to 71.4 feet with no observed drop in RPM. In fact, there was a slight increase in RPM. Normally a test such as this would stall a pump or motor. The present invention justs slips under this closed- valve condition.
Paper Example 2 Assume delivery requirement of 50 feet of head and 100 gallons per minute with 3" by 4" plumbing. Pick an off-the-shelf pump with 1800 r.p.m. and 7~ HP. With a conventional pump designed to operate at a constant speed and a constant delivery, if you varied the speed to vary the delivery, you would get cavitation and rapidly erode the pump parts. The present invention avoids this problem by sizing the pump to use a 3" by 4" impeller.
To vary the delivery from 1 gallon to 5000 gallons per minute, we need only to vary the ~PM from 500 to 3500, getting a head varying from 0 to 150 feet. The entering material finds its natural inflow path along the points of minimal pressure on concave face 31. The user can vary the speed to alter the delivery with no adverse effects on the pump.
Other pumps depend on paddles or vanes to move fluids, not on the ~urface of the impeller, which is at a neutral angle of ~0 degrees to the horizontal on most pumps. The present invention relies entirely on the concave face 31 of the impeller means 30 to impart movement to the pumped material, so the propelling agent is different than in prior art pumps. The present ~ 7~

1 invention has one design for one delivery, varying insize only to fit diferent diameters of input. The reverse plane of concave face 31 produces the laminar action describing an Archimedian spiral as the particles of pumped material pass from the center to the outer edge of the revolving concave face 31.

Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A vaneless centrifugal pump comprising a front plate having a central inlet port, a back plate, and a peripheral output housing and discharge port; a circular rotor to impart laminar movement to fluid material being pumped thereby, the rotor having a concave pumping face opposed to an interior surface of the front plate about the inlet port to form a pumping chamber therebetween, the width of which decreases with increasing radius such that the effective cross-section of the flow channel is substantially constant, and the concave face of the rotor being shaped such that fluid material passing thereagainst is deviated by an angle of more than 90 degrees from its axial direction through the inlet port; the surfaces forming the flow channel from the inlet port through the pumping chamber to the outlet housing being smooth and uninterrupted, so as to maintain laminar flow through the pump.

2. A pump according to claim 1, in which the concave face of the rotor and the opposed interior surface of the front plate are shaped such that fluid material is deviated by an angle of less than 135 degrees.