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Publication numberUS3901623 A
Publication typeGrant
Publication dateAug 26, 1975
Filing dateFeb 8, 1974
Priority dateFeb 8, 1974
Publication numberUS 3901623 A, US 3901623A, US-A-3901623, US3901623 A, US3901623A
InventorsCharles W Grennan
Original AssigneeChandler Evans Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pivotal vane centrifugal
US 3901623 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

[ Aug. 26, 1975 United States Patent Grennan Durdin,

l/1974 FOREIGN PATENTS OR APPLICATIONS m an 6 ea m MK 206 366 999 111 087 16115 .1 1 .3 0008 8568 233 PM mm PM L M m n 8 RT TG N. w S E NIH Amm VCC M: r mm W Pl QM 5U 702 816 1/1954 United Kingdom............. 416/186 A 788,550 H1958 United Kingdom......... 415/129 22 Filed:

Primary Examinerl-lenry F. Raduazo [57] ABSTRACT A centrifugal pump having a radial flow impeller char- [52] US. Cl. 415/141; 415/219 A; 415/DIG. 4; 416/186 A; 415/170 A F0ld 5 12 415/129, 130, acterIzed by plvotally mounted vanes. The vanes are [58] Field of Search 416/186 A;

shaped and positioned with respect to one another whereby the dimensions of the flow channels defined by adjacent vanes may be varied to meet the required pressure conditions.

[56] References Cited UNITED STATES PATENTS 1,406,297 2 1922 415 130 2 Claims, 3 Drawing igur s PATENTED AUG 2 61975 ST'EEET 2 0f 2 PIVOTAL VANECENTRIFUGAL PUMP BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the operating characteristics of pumps and particularly centrifugal pumps which are required to-operate at low flow rates over a wide range of back pressures with a high maximum output pressure. More specifically, this invention is directed to low specific speed pumps with radial stage impellers. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.

2. Description of the Prior Art The present invention has been found to be particularly well suited for use with centrifugal pumps having a radial flow impeller; such pumps having an axial inlet and radial discharge for fluid delivered thereto. The achievement of constant flow, particularly with varying back pressure, has proven to be an elusive objective for designers of centrifugal pumps. Restated, a long felt need in the pump arts is to provide a centrifugal pump which would have the linear pressure-flow characteristics of a positive displacement pump, such as a gear or piston pump, but which would not subject the fluid being pumped to the coarse handling characteristics of a positive displacement pump. Thus, by way of example, there has not previously been available a high pressure, low flow centrifugal pump which would provide an output characterized by minimum hydraulic noise regardless of variations in back pressure. Such a pump would, for example, be desirable for use in any control system sensitive to flow pulsations or in cases where the process fluid could not stand harsh treatment conditions. The processing of food or blood plasma is an example where the process fluid must not be subjected to the coarse handling which is characteristic of positive displacement pumps. Numerous control systems, such as those on submarines, present environments where the hydraulic noise associated with output pressure pulsations is undesirable or unacceptable.

As discussed above, it has long been desired to provide a centrifugal pump which would duplicate the constant flow with varying pressure characteristics of a positive displacement pump. In addition to the above briefly described examples of where such a pump could be employed, it is also to be noted that positive displacement pumps are characteristically sensitive to and thus can not be employed in the handling of contaminated fluids; i.e., fluids with entrained particulate mat ter. Conversely, centrifugal pumps are very insensitive to entrained particulate matter and their ability to handle contaminated fluids is well known. The applications for pumps providing a constant flow at varying back pressures while moving contaminated fluids are numerous.

While the above discussion has emphasized a constant flow rate, it is to be observed that a concomitant long standing desire has been the provision of a centrifugal pump which can affectively and quietly vary its flow and pressure to match system demands. Previous attempts to produce such a pump have resorted to varying pump speed, throttling techniques or variable pump geometry. As is well known, pressure rise and flow may be varied by changing pump speed. However, since the rate of pressure rise does not vary linearly with the flow capacity of a fixed geometry centrifugal pump with increases in speed, variations in pump speed offer a limited solution; i.e., system demands can be matched only over a limited range of pressures and flows. Throttling, and its counterpart bypassing, inherently results in inefficient operation with attendant noise and process fluid temperature increases. Conventional throttling or bypassing techniques are, accordingly, not suitable for environments where either noise or the preservation of the characteristics of the process fluid are considerations. For an example of a centrifugal pump which employs throttling at the inlet, reference may be had to Mottram et al. U.S. Pat. No. 3,442,220. Throttling at the pump input, as is well known in the art, results in cavitation and thus hydraulic noise. There are other centrifugal pumps known in the art which resort to throttling at the pump outlet. U.S. Pat. No. 3,168,870 to Homschuch is representative of the prior art technique of internal bypassing in the interest of varying centrifugal pump capacity.

Centrifugal pumps with variable impeller geometry are also known. For an example of a centrifugal pump with a variable geometry impeller which is adapted to high specific speed applications, reference may be had to copending application Ser. No. 277,593 now U.S. Pat. No. 3,806,278 entitled Centrifugal Pump With Variable Flow Area" which is assigned to the assignee of the present invention. A further approach to variable geometry impellers are those proposed pumps which have blade configurations of conventional crosssection and a single flow channel without pulse generation compensation. For examples of such further proposed variable geometry pumps reference may be had to U.S. Pat. No. 2,927,536 to Rhoades and U.S. Pat. No. 3,482,523 to Morando.

It is to be noted that there have, in the prior art, been hydraulic pump/turbines and variable pitch aircraft propellers which employed pivoting vanes or blades. These prior art devices have, however, been predominantly axial flow machines whereas a centrifugal pump is a radial flow machine. Prior art fluid handling devices with pivotal blades have also been characterized by rather complex external actuators which controlled the pivoting of the vanes or blades about a radial to the main axis of rotation of the devices.

SUMMARY OF THE INVENTION The present invention overcomes the above discussed and other problems of the prior art by providing a novel and improved radial flow centrifugal pump which is characterized by a variable flow area. In accordance with the invention the vanes of a radial flow impeller are pivotally mounted, adjacent their outer periphery, and are shaped and positioned with respect to one another so as to permit adjustment of the dimensions of the flow channels between the pump axial inlet and discharge to meet the required pressure conditions.

In a preferred embodiment the invention employs curved impeller blades designed with an artificial blockage which gives the pump an improved hydraulic radius when compared to the prior art.

Although a conventional volute or diffuser can be employed as the collector, in a preferred embodiment of the invention the pump may be characterized by an axial inlet and toroidal collector. The toroidal collector possesses the desirable features of no cut-water or tongue for generating pressure pulses.

BRIEF DESCRIPTION OF THE DRAWING The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawing wherein like reference numerals refer to like elements in the several figures and in which:

FIG. 1 is a cross-sectional, top view of a preferred embodiment of a self-compensating centrifugal pump with a variable geometry impeller in accordance with the invention;

FIG. 2 is a front elevation view, partially broken away, of the impeller assembly of the pump of FIG. 1 in the high flow, high pressure condition; and

FIG. 3 is a front view, partially broken away, of the impeller assembly of the pump of FIG. 1 in the low flow, low pressure condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring simultaneously to FIGS. l-3, a pump in accordance with the preferred embodiment of the present invention includes a housing which defines an axial inlet and a toroidal collector 12. As discussed above, the pump includes a pivoting vane impeller assembly. This impeller assembly is defined by a plurality of pivotally mounted blades disposed between vaneless front and back shrounds. The front shroud, or driven vane retainer, is indicated at 14. The back shroud, or driver vane retainer, is indicated at 16. The driver and driven retainer are held together by a plurality of through bolts and associated spacers. One of several through bolts is shown at 18 in FIG. 1. A sleeve or spacer 20 is disposed about each of the through bolts 18; the sleeves being located by means of engagement with shoulders formed on the facing surfaces of the driver and driven vane retainers. The sleeves 20 provide the pivot points for the vanes, such as vane 22, and also as the anchors for preload torsion springs, such as spring 24.

The impeller assembly is keyed to the pump drive shaft 34 and is held in position on the drive shaft by means of a lock nut 26. A conventional face seal assembly, indicated generally at 28, engages the rearwardly facing side of the driver retainer 16 as shown. Wear rings and 32 are respectively provided, for thrust balancing purposes, between flanges on the driver and driven vane retainers and the pump housing. The wear rings 30 and 32 are located to balance axial thrust loads, as is common with prior art open face impellers, and these wear rings seal the impeller discharge respectively to the impeller assembly back face and inlet. Conventional labyrinth seals may be employed in place of wear rings 30 and 32.

FIG. 2 shows the vanes of the pump of FIG. 1 in the high pressure-high volume flow position. FIG. 3 shows the vanes in the low pressure-low volume position. Through joint consideration of FIGS. 2 and 3 it may be seen that the area of the flow channels defined by the spaces between the pivoting vanes is variable. The vanes 22 are conventionally curved backwardly. The vanes 22 are, however, of unusual width when compared to the prior art. The increased width, at the downstream or discharge ends of the vanes, is achieved by shaping the vanes whereby they impart an artificial blockage to fluid flow thereby improving the hydraulic radius of the impeller. In terms of fluid mechanics the impeller of the present invention thus approaches the optimum hydraulic radius; i.e., the minimum friction loss; for a given flow area.

Pumps in accordance with the present invention are self-compensating and operation of the pivoting vane impeller is effected by the action of the back pressure against the vane surfaces producing a moment around the pivot point. The net effect of this moment, the inertial and centripetal loads plus the pivot friction is resisted by the coil springs 24 around each pivot; the coil springs having a tang which engages the walls of a recess formed in each blade as shown in FIG. 1. Increasing back pressure thus increases the blade-to-blade channel width, the effective outside diameter of the impeller and the blade angle. All of these factors improve the impellers ability to sustain the requisite flow against the higher back pressure.

While a preferred embodiment has been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is: 1. In a radial flow centrifugal pump, said pump having a drive shaft and a housing which defines an axial inlet and a collector for receiving fluid being pumped, means for varying the pump flow area comprising:

impeller means, said impeller means including a plurality of pivotally mounted vanes, said vanes being pivotal about axes oriented parallelly to and disposed circumferentially about the axis of rotation of the impeller means, said vanes being mounted for pivoting adjacent their discharge ends and being characterized by increasing width from their inlet to discharge ends, said vanes cooperating to define flow channels of variable width therebetween, the shape and mounting of each of said vanes resulting in the generation of a pivotal moment in the direction of maximum flow channel width in response to the summation of the pressure and mechanical forces applied to the vanes;

means for mounting said impeller means on the pump drive shaft; and

spring means for loading said pivotal vanes toward the channel width position commensurate with minimum flow, said spring means generating forces substantially equal and opposite to the pressure and mechanical forces imposed on the vanes under minimum flow conditions, on the operation of said pump the pressure forces on the vanes and thus the pump blade-to-blade channel width increasing in response to increases in pump back pressure.

2. The apparatus of claim 1 wherein said spring means each comprises:

a torsion spring.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1406297 *Jun 1, 1920Feb 14, 1922Stewart Alfred CCentrifugal pump
US1880911 *Nov 3, 1928Oct 4, 1932Durdin Jr Augustus CSeal for shaft bearings
US2950686 *Mar 20, 1958Aug 30, 1960Thompson Ramo Wooldridge IncVariable centrifugal pump
US3260311 *Jul 5, 1963Jul 12, 1966Foster Wheeler CorpVane adjusting device for pump impellers and turbine wheels
US3788765 *Nov 18, 1971Jan 29, 1974Laval TurbineLow specific speed compressor
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4172310 *Jan 12, 1978Oct 30, 1979Societe Internationale De Mecanique Industrielle S.A.Improvement in assembling a centrifugal pump
US4589822 *Jul 9, 1984May 20, 1986Mici Limited Partnership IvCentrifugal blood pump with impeller
US4606698 *Jul 9, 1984Aug 19, 1986Mici Limited Partnership IvCentrifugal blood pump with tapered shaft seal
US4662819 *Apr 10, 1986May 5, 1987American Standard Inc.Centrifugal fan with variable blade pitch
US4898518 *Aug 31, 1988Feb 6, 1990Minnesota Mining & Manufacturing CompanyShaft driven disposable centrifugal pump
US5263924 *Sep 25, 1991Nov 23, 1993Baxter International Inc.Integrated low priming volume centrifugal pump and membrane oxygenator
US5591404 *Jul 23, 1993Jan 7, 1997Mathewson; WilfredIntegrated low priming volume centrifugal pump and membrane oxygenator
US6074167 *Feb 5, 1999Jun 13, 2000Woodward Governor CompanyVariable geometry centrifugal pump
US6474936Apr 13, 2001Nov 5, 2002Hewlett-Packard CompanyBlower impeller apparatus with one way valves
US6547519 *Apr 13, 2001Apr 15, 2003Hewlett Packard Development Company, L.P.Blower impeller apparatus with pivotable blades
US6935839 *Apr 12, 2001Aug 30, 2005Tesma International Inc.Variable flow water pump
US7001155 *May 14, 2003Feb 21, 2006Honeywell International, Inc.Compressor impeller with stress riser
US7553124 *Jul 17, 2006Jun 30, 2009Juan JimenezPump for pumping high-viscosity liquids, slurries, and liquids with solids
US8641378 *Apr 11, 2011Feb 4, 2014Yamada Manufacturing Co., Ltd.Impeller for water pump
US20030165383 *Apr 12, 2001Sep 4, 2003Pascoe David MarkVariable flow water pump
US20040022648 *May 14, 2003Feb 5, 2004Jose CabralesCompressor impeller
US20110255970 *Apr 11, 2011Oct 20, 2011Yamada Manufacturing Co., Ltd.Impeller for water pump
EP2395245A3 *Apr 12, 2001Jul 6, 2016Magna Powertrain Inc.Variable flow water pump
WO2001079703A1 *Apr 12, 2001Oct 25, 2001Tesma International Inc.Variable flow water pump
U.S. Classification415/141, 416/244.00R, 415/224.5, 415/174.2, 416/186.00A, 415/900
International ClassificationF04D29/24, F04D15/00
Cooperative ClassificationF04D29/247, F04D15/0055, Y10S415/90
European ClassificationF04D29/24B, F04D15/00D
Legal Events
Apr 8, 1992ASAssignment
Effective date: 19920401
Apr 8, 1992AS06Security interest
Effective date: 19920401
Mar 30, 1992ASAssignment
Effective date: 19900503
Jul 10, 1987ASAssignment
Effective date: 19861028
Effective date: 19870706