US 3575525 A
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Description (OCR text may contain errors)
United States Patent Leonard J. Fox
Paul E. Kueser, Pittsburgh, Pa. 776,509
Nov. 18, 1968 Apr. 20, 1971 Westinghouse Electric Corporation Pittsburgh, Pa.
Inventors Appl. No. Filed Patented Assignee PUMP STRUCTURE WITH CONICAL SHAPED INLET PORTION 4 Claims, 1 Drawing Fig.
US. Cl 415/215, 415/204, 415/212 Int. Cl ..F04d 13/12, F04d 25/16, F04d 25/06 Field of Search 103/84,
References Cited UNITED STATES PATENTS 2,877,710 3/1959 Bamhart 103/89 718,557 l/l903 Wenzel 103/88 1,810,083 6/1931 Norinder 103/84 2,528,210 10/1950 Stewart 103/114 2,777,394 1/1957 Modrovsky et a1. 103/84 Primary Examiner-Henry F. Raduazo Attorneys A. T. Stratton, F. P. Lyle and E. Strickland ABSTRACT: A pump, particularly suitable for pumping liquid molten metals, comprising an elongated, tapered or coneshaped rotor disposed coaxially in a housing structure having an inner space with a similar shape, and having inlet and outlet ends, the radii of the rotor and/or the inner space of the housing increasing in the direction of the outlet end, the rotor and housing fomiing a space therebetween for directing a flow of liquid therethrough.
' J PATENTEVVD M20197:
INVENTORS Leonard J. Fox and Poul E. Kueeser 5W 5 ATTORNEY lPlUMlP STRUCTU WITH CONICAL SHAPED INLET PORTTON BACKGROUND OF THE INVENTION The present invention relates to a pump structure particularly suitable for circulating and transferring highly viscous liquids, for example, molten metal.
More particularly, the invention presents a substantial improvement in pumps presently available for pumping liquid metal, two of such pumps being disclosed by Faul l-l. Scheffler and Paul H. Scheffler et al., respectively, in copending applications Ser. No. 610,935 (now U.S. Pat. No. 3,459,133) and Ser. No. 761,024 filed Jan. 23, 1966 and Sept. 20, 1968, respectively, and assigned to the present assignee.
The pumps disclosed in the two copending applications operate on the forced vortex" principle to prime an impeller forming an integral part of an elongated rotor. These pumps have been highly successful in pumping viscous substances, and therefore, have provided substantial improvements over pumps available at the time of their development.
However, certain disadvantages exist with the disclosed pumps. First of all, the pumps are large and heavy, the pumps using the interior of a hollow rotor having a relatively thick wall portion to produce the forced vortex of liquid for pumping. Secondly, the rotor is fabricated from a plurality of parts which must be cemented or otherwise secured together thereby increasing the cost of fabricating the pump. Thirdly, a minimum clearance between the vanes on the rotor impeller and the outer housing is needed to seal the impeller stage from the inlet section.
BRIEF SUMMARY OF THE INVENTION Broadly, the present invention employs a rotor coaxially disposed in a casing or housing having an inlet end and an outlet end, the interior of the housing being formed to have a tapered configuration, the radius of which increases in the direction of the outlet end of said housing. The rotor is elongated and is preferably a solid structure having a tapered configuration similar to that of the housing interior though the invention is not limited thereto. For example, the rotor may be a cylinder and function properly. Further, the rotor surface may be provided with grooves or ribbing to facilitate pumping. Similarly, the internal surface of the housing may be provided with a spiral groove. The rotor, together with the inside surface of the housing, forms an elongated annular path or space for liquid flow.
With rotation of the rotor and a head of liquid to pump, a tangential velocity is imparted to the liquid in contact with the surface of the rotor cone. This liquid is propelled outwardly from the cone and strikes the inside surface of the housing wall where it is redirected. The resultant direction of liquid flow is towards the wide base of the housing outlet and rotor cones, or away from the apex of the cone, and in the direction of rotor rotation. Since the path of liquid flow has an increasing radius in the direction of desired flow, an increasing velocity component is imparted to the liquid as it travels through the pump.
The rotor of the present invention has distinct advantages over the rotor disclosed in the above-mentioned applications. First of all, the rotor can be made of a single solid piece of material, i.e., a solid cone which greatly simplifies and economizes rotor fabrication while simultaneously providing a rugged rotor construction which can withstand high rotational speeds.
Secondly, with the present rotor, the pump can be made smaller and more compact since the liquid being pumped travels on the outside of the rotor thereby eliminating the thickness of the rotor wall of hollow rotors.
Other advantages accrue with the present invention as will be explained hereinafter.
THE DRAWINGS The invention, along with its objectives and advantages, will be best understood from consideration of the following detailed description taken in connection with the accompanying drawing in which the sole FIGURE shows a vertical section of a pump constructed in accordance with the principles of the present invention.
PREFERRED EMBODIMENT the surface of the rotor portion 18 form an annular, elongated space 21 defining a path for the flow of liquid to be pumped as indicated by the arrows in said space.
A drive shaft 22 extends through an opening 24 provided in the volute collector 14, and into a bore 25 provided in the upper end of the rotor 16. The end of the shaft is secured in the bore to form a mechanically rigid connection between the shaft and rotor for rotating the rotor. The opening 24 need not be sealed for reasons explained hereinafter.
The drive shaft is supported in a bearing assembly 26 only representatively shown in the FIGURE.
The housing portions, rotor and drive shaft are made from hard, heat resistant materials, such as silicon carbide, in order to withstand the high temperature, corrosive environment of molten metals.
The inlet housing 12 is provided with an inlet orifice or opening 28 for admitting the liquid to be pumped into the housing, while the volute housing 14 is provided with an outlet port 30 for directing liquid from the pump.
The inlet and volute housings l2 and 14 may be further provided with flange portions 32 and 33 respectively for joining and sealing together to form an overall housing unit. The portions may be held together by a suitable clamping assembly, for example, the assembly shown and described in the above-mentioned Scheffler et al. application. The volute housing portion 14 has its largest radius toward the inlet housing 12.
In accordance with the invention, the elongated portion 18 of the rotor 16, and the interior or inner space of the inlet housing 12 form coaxially disposed solid figures traced about a vertical axis and having increasing radii and diameters in the direction of the impeller 20, though the rotor portion 18 may be a cylinder (i.e., a solid figure with a constant radius) and yet function properly in a manner presently to be explained.
As shown in the drawing, the solid figures may be cone shaped, the radii thereof increasing in a direction away from the apices of the cones. In addition, the rotor 16 is shown as a solid body structure having a smooth outer surface though a hollow or cored body could be employed, and the outer surface could be provided with ribs or grooves. Similarly, the inside surface of the inlet housing 12 may be provided with a spiral groove or grooves.
As shown further in the drawing, the rotor 16 includes the upper portion 20 which functions as a centrifugal impeller in a manner presently to be explained. The impeller is formed by providing the underside of the upper portion with circumferentially spaced, radially extending vanes 35, the vanes being shown in elevation in the drawing. In this manner, the liquid flow path 21 is placed in convenient continuous fluid communication with the vanes, as indicated by appropriate arrows.
For operation, the pump 10 may be placed in a pool (not shown) of liquid molten metal to function as an immersible unit, or it can be operated outside a process vessel or furnace containing the molten metal. ln the latter case,. a suitable conduit would be connected between the inlet port 28 of the pump and an outlet port provided in the vessel containing the liquid.
The rotor 16 of the pump is rotated by a suitable prime mover (not shown) acting upon the drive shaft 22. With rotation of the rotor, the liquid to be pumped enters the inlet housing 12 through the port 28, and is directed up through the space 21 towards the impeller in the following manner.
As the conical portion 18 of the rotor 16 rotates, a tangential velocity is imparted to the liquid in contact therewith. This liquid is directed outwardly away from the rotor and towards the inner surface of the housing 12. The liquid strikes the inner surface with a force that is resultant in the upward direction, as well as in direction of rotor rotation. because of the inclined inner surface of the housing 12. The liquid is thus directed up through the space 21 towards the impeller 20. Since the radius of the inner surface adjacent the space 21 increases in the direction of the desired flow, a higher velocity is imparted to the liquid as it travels in said direction.
From the space 21, the liquid being pumped is directed between the vanes 35 of the impeller 20 in a radially outward direction, and by virtue of the rotation of the impeller, the velocity of the liquid is tangential in direction as it leaves the edges of the vanes.
The liquid leaving the impeller vanes 35 strikes the inside surface of the collector housing 14, which is preferably a volute surface, said surface collecting and redirecting the tangential velocity component of the liquid flow to linear flow for discharge through the outlet port 30.
In certain tests conducted with the pump 10, a spiral rib (not shown) was provided on the rotor portion 18. The rib enhanced the capabilities of the pump to the extent that the pump continued to function well when the liquid level or priming head was lowered to a level 2 feet below the port 28, a conduit (not shown) being connected to the port and extending into the liquid.
ln applications involving high flow rates and low pumping heads, the pump 10 does not need an impeller for proper functioning of the pump. This is particularly true in pumping abrasive slum'es where excessive wearing away of the impeller vanes could result.
The impeller 20, however, does have certain advantages over the impeller shown in the above-mentioned Scheffler application. As shown in the FIGURE and as described above, the impeller vanes 35 are formed on the underside of the impeller so that the space between the inner surface of the housing 12 and the vanes is the path of liquid flow. For this reason, a minimum clearance between said surface and vanes is not necessary to form a seal between the inlet and discharge portions of the pump. In the Scheffler application, the path of liquid flow is inside the rotor and over the top of an impeller having vanes facing in an upward direction. This requires a minimum clearance between the impeller and inlet housing to prevent the return of liquid in the discharge section to the inlet section.
For the same reason, the pump of the present invention can operate under higher pressure heads without fluid leakage along the drive shaft 22. The flow of liquid along the underside of the impeller 20 reduces the tendency of the liquid to flow up towards the opening 24 existing between the shaft and the volute housing 14. In the pumps of the above-mentioned copending applications, there is this tendency since the upwardly facing vanes and liquid flow are in closer proximity to the opening in the volute collector for accommodating the drive shaft.
As explained earlier, the path of liquid flow through the pump 10 is along the outside of the rotor 16 which allows the use of a smaller, more compact rotor since the wall thickness of a hollow rotor is eliminated. This, in turn, reduces the overall size of the pump. Further, the rotor can be made as a solid single-piece structure thereby substantial] reducing the cost of making the rotor while simultaneousy providing a rugged rotor structure for high-speed rotation.
It should now be apparent from the foregoing description a new and useful pump has been disclosed in which the path of liquid flow is along a space between an elongated rotor and a surrounding housing having an inner tapered space, the space and rotor defining solid figures drawn about a central axis, said tapered space having an increasing radius in the direction of liquid flow through the pump.
Though the invention has been described with a certain degree of particularity, changes may be made therein without departing from the spirit and scope thereof. For example, the rotor portion 18 and the interior of the housing 12 need not define cone figures, i.e., figures having linear tapers. The tapers may be nonlinear such as an ellipsoid, and the taper of the rotor and housing may be the same or different depending upon the pumping characteristics desired.
1. A pump adapted to be vertically positioned comprising:
a housing structure having an inlet at the lower end and an outlet in the upper end,
said housing having an inlet housing portion at said inlet end and extending toward said outlet end, said inlet housing portion having an inner surface defining a tapered solid figure traced about a vertical axis, and having an increasing radius in the direction of said outlet end,
an outlet housing portion joined with said inlet housing portion and having a collecting volute structure with an open side joined to said inlet housing portion,
a rotor disposed coaxially in said housing structure and adapted to be supported by a bearing means adjacent said housing structure, said rotor having an elongated portion defining a solid figure traced about said vertical axis,
said rotor and said inlet housing portion defining an elongated annular space between them,
said rotor including a centrifugal impeller disposed at the end of the rotor enclosed by said outlet housing portion, said impeller including an upper continuous wall portion extending radially outward from said elongated portion of said rotor and having a side facing said inlet housing end, and a plurality of circumferentially spaced vanes extending from said side of said upper portion toward said inlet end, said continuous upper wall portion and said vanes cooperating to induce flow away from said bearing means on rotation of said rotor,
means for rotating said rotor,
said rotor and housing being effective to direct a flow of liquid through said annular space at an increasing velocity in the direction of the increasing radius when said rotor is rotated.
2. The pump described in claim 1 in which the rotor is a solid, one-piece structure.
3. The pump described in claim 1 in which the housing and rotor are made from silicon carbide.
4. The pump claimed in claim 1 in which the inlet housing and elongated rotor portions define cone figures having increasing radii in the direction of the outlet end of the housing.