US3196795A

US3196795A - Electromagnetic pump system

Info

Publication number: US3196795A
Application number: US248935A
Authority: US
Inventors: Richard S Baker
Original assignee: North American Aviation Corp
Current assignee: North American Aviation Corp
Priority date: 1963-01-02
Filing date: 1963-01-02
Publication date: 1965-07-27
Anticipated expiration: 1982-07-27
Also published as: NO116702B; CH416329A; DE1553138A1; SE310026B; AT271209B

Description

July 27, 1965 R. s. BAKER 3,196,795

ELECTROMAGNETIC PUMP SYSTEM Filed Jan. :2, 1963 5 sheets-sheet 2 |22 |2o\ oo flae -IOZ- E- j /Z f i l |04/ |03 |05\} u2 'I3 Y INVENTOR` RICHARD sl BAKER nOg/M492 `AGENT July 27, 1965 R. s. BAKER 3,196,795

ned Jan. 2, 196s 5 sheets-sheet :s

July 27, 1965 R. s. BAKER ELECTROMAGNETIC PUMP SYSTEM 5 Sheets-Sheet 4 Filed Jan. 2, 1963 INVENTOR.

RICHARD' S. BAKER AGENT July 27, 1965 R. s. BAKER ELECTROMAGNETIC PUMP SYSTEM 5 Sheets-Sheet Filed Jan. 2, 1963 INVENTOR.

RICHARD S. BAKER AGENT United States Patent O 3,195,795 ELECTROMAGNETIC PUMP SYSTEM Richard S. Baker, Northridge, Calif., assigner to North American Aviation, Inc.

Filed Jan. 2, 1963, Ser. No. 248,935 7 Claims. (Cl. 103-1) The present invention relates to an electromagnetic pump system for the transfer of electrically conductive liquids and more particularly to an electromagnetic interaction pump system for the transfer of high temperature liquid metals. The improved pump system of the present invention is based upon the principle of operation of my helical rotor electromagnetic pump disclosed in United States Patent No. 2,940,393, issued June 14, 1960, and assigned to the same assignee as the present invention.

Although conventional mechanical and electromagnetic pumps are generally well-known in the prior art, modern foundry practice depends primarily on gravity and Siphoninduced flow arrangements to transfer liquid metals, particularly very high temperature liquid metals such as aluminum, zinc, nickel, brass and the like. Conventional mechanical pumps for practical reasons have been limited in modern foundry practice to `low temperature, noncorrosive liquid metals. These pumps cannot be used for pumping high temperature liquid metals since the moving parts generally formed from iron or steel rapidly deteriorate in the corrosive environment of most liquid metals.

Electromagnetic pumps are adapted for use in modern foundry practice, particularly in the transfer of conductive liquids, since there are no moving parts in contact with the liquid being pumped. The magnetic impeller in an electromagnetic pump replaces the mechanical impeller of a mechanical pump. Electromagnetic pumps develop a pumping force by converting magnetic energy into pressure energy in accordance with the electromagnetic thrust that is generated by the passage of an electric current, either applied or induced, through an electrically conductive liquid transversely to a magnetic field. The direction of force acting upon the conductive liquid and the resulting liquid motion are determined by the well-known three nger rule of electrophysies.

The maior problem in the operation of any electromagnetic pump in modern foundry practice is the vulnerability of the conductors and the insulation in the field winding to high temperature. rl`his factor is commonly the result of high temperatures associated with the liqiud metal being pumped. For example, electromagnetic conduction pumps have relatively heavy conductors or bus bars which serve as electrode connections to the pumping section. These bus bars are generally secured to the pumping section by bre-.zing or welding and are therefore susceptible to breaking away from the pumping section when a high temperature liquid metal is being pumped. When the bus bars in a conduction pump are formed from materials having better metallurgical properties, lower pump efficiencies result which are frequently no greater than 2 or 3 percent in pumps having any appreciable capacity. Linear induction pumps which operate on the theory of an induction motor generally require eX- pensive polyphase field windings. An electrical current is induced in the liquid metal being pumped by a magnetic field set up by alternating currents flowing in windings in a magnet structure surrounding the pump section. While efiicient pumping generally results, induction pumps are expensive, structurally expansive, and susceptible to the high temperature factor.

Modern foundry practice, therefore, has had to depend primarily on gravity and Siphon-induced ow arrangements to transfer liquid metals, particularly the very high temperature liquid metals. The transfer of the liquid CII 3,196,795 Patented July 27, 1965 ICC metal or melt in foundry practice is preferably without excessive agitation of the melt and without rupture of a protective oxide skin that forms on the surface of the melt. This oxide skin substantially reduces both the gas adsorption by the melt and the related accumulation of dross or slag therein. When the oxide skin remains unbroken and the melt transfer is calm, a relatively clean molten metal results that is suitable for pouring high quality castings having a desirable low porosity. Without exacting control provisions, the gravity and Siphoninduced transfer Hows currently used `by modern foundry practice substantially increase the probability of high gas adsorption by the melt since rupture of the oxide skin and excessive agitation of the melt are unavoidable.

A rotating field electromagnetic pump is particularly adapted for the desired calm transfer of liquid metals in modern foundry practice. However, high temperature liquid metals require an improved field coil windingr and rotor geometry which promotes adequate cooling and substantially increases the efliciency of the pump during high temperature pumping. The necessary bearing arrangements in rotating field electromagnetic pumps are also subjected to the hightemperature environment. It is desirable to position the bearing arrangements for a rotating eld pump in a region removed from the high temperature environment without sacrificing stability of the rotating pump components.

Accordingly, it is a primary object of the present invention to provide an electromagnetic pump system for pumping electrically conductive liquids, particularly high temperature liquid metals.

It is also an object of the invention to provide an electromagnetic pump system that pumps a liquid metal from beneath the surface of a melt without rupture of the protective oxide slrin on the melt surface.

A further object of the invention is to provide an electromagnetic pump system which transfers the liquid metal from one location to another without an appreciable increase in `gas adsorption by the melt or related dross formation therein.

Another object of the invention is to provide an electromagnetie interaction pump system for pumping electrically conductive liquids against the action of gravity -by developed electromagnetic forces.

Yet another object of the invention is to provide an electromagnetic pump system that develops a pumping action by the production of a force on the liquid in the desired direction of flow by an electromagnetic interaction that is produced by the helical geometry of the pump rotor.

It is also an object of the invention to provide an electromagnetic pump system with adequate cooling of the helical pump rotor.

Yet another object of the invention is to provide an electromagnetic pump system having an improved bearing arrangement for the helical pump rotor.

An additional object of the invention is to provide an electromagnetic pump system that develops a calm ow of liquid metal under pump induced pressure without complex guide vane configurations in the pump liquid ow passages.

Likewise an object of the invention is to provide an electromagnetic pump system that facilitates accurate control of the l'low of a liquid under pump induced pressure.

A further object of the invention is to provide a method and apparatus to stir a melt to maintain homogeneity thereof.

Yet another object of the invention is to provide a method and apparatus for substantially cleaning pump system ow passages of liquid by a reversal of the developed electromagnetic forces.

Further objects, features and the attending advantages of the invention will be apparent with regard to the following description read in connection with the accompanying drawings in which:

FIGURE 1 is a perspective view, partly broken away, of one form of the electromagnetic pump system of the invention;

FIGURE 2 is a perspective view of the pump system of FIGURE 1 in an operating location;

FIGURE 3 is a longitudinal section, partly schematic, of the pump system of FIGURE l;

FIGURE 4 is a perspective view of another form of the electromagnetic pump system in an operating location;

FIGURE 5 is a perspective view, partly broken away, of the pump system of FIGURE 4;

FIGURE 6 is a longitudinal section, partly schematic, of yet another form of the electromagnetic pump system of the invention; and

FIGURE 7 is both a perspective view and a developed view of one form of my helical pump rotor as disclosed.

Briefly, in accordance with one form of the invention, an electromagnetic pump system for pumping electrically conductive liquids is provided having at least one pump region that is juxtaposed between a magnetic helical rotor, which sets up a magnetic flux field across the pump region and distributes the field in a generally helical curve, and a flux return path so that when the rotor is rotated by a suitable drive means, the magnetic flux tield induces electrical eddy-currents in a liquid in the pump region that flow in patterns which conform with the helical geometry of the rotor and interact with the magnetic tield to impart desired pumping forces on the liquid in the pump region.

Referring to FIGURE 1, one form of the electromagnetic pump system of the invention has an outer crucible member 10 supported by a plurality of refractory bricks 12 or the like. The bricks 12 protect the pump system components and provide thermal insulation for the pump system. A radially extending ange 13 of the crucible 19 provides a bearing surface or platform for a lip edge 15 of an inner crucible member 16 that is nested within the outer crucible. Both the outer and

inner crucibles

10 and 16 are oriented in a generally vertical alignment about a vertical axis. It is contemplated that the certain degrees of tilt from the vertical alignment shown by FIGURES 1 and 2 also are within the inventive concept. A spring clamping means, not shown, can be provided to ensure the relative positions of the

crucibles

10 and 16 since the inner crucible 16 may have a tendency to be buoyed up when certain liquid metals and their alloys are being pumped by the pump system of the invention.

The outer and inner crucible members 1t) and 16 are preferably formed from a suitable refractory material such as silicon carbide, boron nitride and the like. The particular metal or refractory material utilized for the flow passages of the pump system is not critical to the principle of operation of my electromagnetic pump system. The choice of material is a function of pressure, type of liquid being pumped, and temperature; the flow passages should be particularly adapted to withstand high operating temperatures such as those incurred when pumping molten metals like aluminum, zinc, brass and the like. While the

crucible members

10 and 16 are shown by FIGURE 1 as integral, individual units that are preformed from a refractory material, it is contemplated that for ease of construction and assembly the

members

10 and 16 could be sectionalized, bonded together by a suitable mortar or sealing agent, and built up into the generally cup-shaped crucible members.

In the nested arrangement, the outer and

inner crucible members

10 and 16 are spaced apart to develop a pump region or annulus 20 therebetween. The crucible members also form an inlet region 21 that communicates with the pump annulus 20. The lip edge 1.5 of the inner crucible 16 develops an outlet region or discharge scroll 22 that also communicates with the pump annulus 2t). Suitable spacer members, not shown, may be provided between the nested outer and

inner crucibles

10 and 16.

At least one inlet port 25 and one outlet port 26 communicate with the inlet region 21 and the outlet region 22, respectively, as shown by FIGURE l. The inlet port 25, while shown in the side wall of the outer crucible 10 can also be positioned in the bottom wall of the outer crucible. Further, the inlet port 25 can be tangentially directed with regard to the inlet region 21. It is contemplated that more than one ingress duct can communicate with the inlet port 25 of the pump system so that melt can be pumped from one or more levels beneath the protective oxide skin on the surface of a melt body. The gentle pumping action developed by the electromagnetic interaction pump system of the invention further ensures a clean liquid metal for subsequent pouring without rupturing the oxide skin during pumping.

If any dross or slag accumulation should occur in the pump annulus 20 or its

related regions

21 and 22, the nested arrangement of the outer and

inner crucibles

10 and 16 facilitates the removal of the inner crucible to expose such accumulation for easy cleaning by mechanical tools and the like. However, during pumping, the continuous scrubbing of the pump annulus 2t) by the developed pumping action, to be subsequently described, minimizes such dross or slag accumulation therein and maintains a relatively clean pump annulus at all times. Thus the need for mechanical tools to clean the pump annulus 20 and the inlet and

outlet regions

21 and 22 is substantially avoided by the structural arrangement and principle of operation of the present invention. Although it is not critical to the operation of the present pump system, the bottom wall of the outer crucible 10 may slope to facilitate drainage of the inlet region 21, the pump annulus 20, and the outlet region 22.

FIGURE 2 shows one form of a structural beam arrangement 30 for the electromagnetic pump system when the pump system is positioned adjacent to a melting furnace or hold pot 32 such as those well-known in the foundry art. The pump system of the invention can also be positioned, for example, between one or more melting furnaces and hold pots, or any combination thereof, or between separate hearths of one or more reverberatory furnaces, or at any other location in a foundry operation where it is desirable to transfer liquid metal.

A prime mover, such as an electric drive motor 35, is supported and positioned by the bearn arrangement 30 above the nested

crucible members

10 and 16. A rotor shaft 36 is connected to the drive motors 35. The shaft 36 can be either solid or hollow, the latter being particularly desirable for the introduction of a cooling medium such as air to the rotating pump components subsequently described. A suitable bearing arrangement 38, more clearly shown by FIGURE 1, rotatably positions the rotor shaft 36 so that the shaft depends into the cup region of the inner crucible 16. The bearing arrangement 3S is positioned above and external to the volume defined by the pump annulus 29 and the inlet region 21. This arrangement removes the bearings from the primary high temperature environment developed during the pumping of high temperature liquid metals and permits adequate cooling by the open location.

A helical rotor 40 is field wound and can be attached to or integrally formed with the rotor shaft 36. The helical rotor 40, as shown in FIGURE 1, has the form of a two-pole electromagnet with

pole pieces

42 and 43; however, the helical rotor 40 can also have a cruciform or any other suitable multipolar form. Both the rotor shaft 36 and the helical rotor 40 are preferably formed from a magnetic material such as mild carbon steel. The helical rotor 40 is formed with at least one helical thread 45.' more clearly shown by FIGURE 3. It is desirable that both the pitch or the helical thread 45 and the width of the thread crest permit a separation between adjacent thread traces on one side oi the rotor 49 to reduce flux leakage paths. Further, it is desirable that the helical thread l5 have a sulicient trace length to travel approximately the axial lcngtlLoi the pump annulus 20 during rotation of the helical rotor lli?.

A field coil winding 47 is wound in the thread t5 between the

adlacent poles

42 and 43 of the helical rotor di). The field coil winding 7 is preferably formed from silicone-impregnated double glass insulated copper wire which particularly adapted for high temperature operating conditions. For rotor operating temperatures in the range 600 F. to 1lG0 F., nickel-clad copper wire with ceramic insulation is preferred. The field winding 47 is insulated from the rotor lo by means of glass saddles or blades, not shown. Thos also serve to produce ventilating ducts or i'iow passages between the rotor and the winding. The field coil winding 47 is electrically connected to an external direct current power source, not shown, by means of suitable slip rings 49. The field wind- -fl' is connected so that adjacent eld poles, such as pole pieces 42 amv 43, produce magnetic poles of opposite polarity. All the turns of the field coil winding 47 on each pole piece 42 and i3 act along the same axis, thereby concentrating the magnetomotive force. This makes the i elical rotor electromagnetic pump particularly suitable for use where the pump annulus 20 must be relatively thick-walled. The slip rings 49 are connected through `iifzihle brushes and leads to the external power source. A plurality of clamping strips or bands 50-52- retain the field coil winding 47 within the helical thread 45.

A protective iaclrct S5 can be secured to and generally enclose the helical rotor 4i). The jacket 55 is preferably to mcd from a suitable material such as stainless steel and prot-3c s the field coil winding 47 from the effects of high temperature operating conditions when handling molten metals. Based upon design parameters, additional l transfer barriers, in addition to the jacket 55, can be L ioned within the inner Crucible i6 between the periphery of the helical rotor f-ll and the wall of the Crucible whis maint a cool?. t flow path therebetween.

The rotating pump components` which include the rotor .tinto the generally cup-shaped interior ofthe inner lc member 16 with t .e pump annulus 20 generally ,iacent to the helical rotor fit). The pump annulus tot in tluiil communication with the rotating comporlli-e mechanically rotating co nponents therefore are not weit-:d by direct immersion in the liquid metal nt is being pumped. The geometry of the helical rotor o and the field coil winding i7 complements the cupsiaped inner Crucible member lo and provides an unobstructed 'low of co" ing air to the rotating pump compole niain lining a total nominal air gap which insures a hiyc i, eru rotor ele; netic pump system. if a higher flow rate is desired, suitable blower arrangements auch as those llnown in the art can oe utilized to inet ^sc the normal .ir'ow.

ly constructed in. gnetic structure 5S is arranged mir-cent to the pump region cr annulus 2t) and provides a tlux return path to improve the over all pump system efficiency by reducing-g lo ige flux. The magnetic structure 58 is preferably bi t-up from a plurality of laminations formed from a goed c .de of magnetic material as silicon steel which may be individually coated with a suitable insulating material. It is generally desirable, particularly when pum ng high temperature liquid metals, to maintain the magnetic structure 53 at a temperature that s than the Curie temperature of the laminations. A cooling medium, such as air, is introduced to the i iagnetic structure 5S from an external source, not shown, through at least one inlet conduit Si). A plenum region or tube distributes the coolng air to a plurality of similar circumfercntially spaced ducts 62, and then ex- 5 liausts the cooling air from the magnetic structure through at least one dischargepipe 63.

In operation, the field coil winding 47 of the electromagnetic pump system shown by FIGURE 1 and 2 is energized from the direct current power supply, not shown, so that the helical rotor 45t as a source of magnetic flux has alternate north and south polarities skewed circumferentiiilly and axially relative to the axis of rotation of the helical rotor. The helical rotor 40 is not homopolar in my helical rotor pump since the opposing north and south polarities develop related opposite polarities in the regions immediately adiacent to the rotor shaft 36. The magnetic flux field set up by the energization of the field winding 4'/ is more clearly shown by FIGURE 3. The magnetic flux eld passes from the skewed north poles of the helical rotor 48 through the pump annulus 26 and the conducting liquid therein to the flux return path provided by the niagnetic structure S8. The magnetic field divides into at least two llow paths, each of which returns to the regions immediately adjacent to the skewed south poles of the helical rotor 49. The flux field then passes back through the pump annulus 2t) to the south poles. The direction of the magnetic flux lield in the pump section 20 is substantially radial to the axis of rotation of the helical rotor 49, and is distributed in tlux patterns or paths that define at least one generally helical curve about the rotor.

Rotation of the energized field wound helical rotor 4i), for example, in a counter-clockwise direction, i.e. from left to right as viewed in FGURES 1 and 2, develops a variance in the magnetic ux field across the pump region or annulus 2l). Referring to FIGURE 7, this variance induces voltages such as along current paths A-B and C-D in the pump annulus 20 in accordance with the right-hand rule of electrophysics. These voltages interact with the magnetic tiel-:l to produce the electromagnetic thrust or force F on the conducting liquid in the pump annulus 2li in accordance with the left-hand rule of electrophysics. My helical rotor pump develops the resultant vector force F that has both axial and circumferential vector components, fa and fc respectively. The development of the axial component fa permits the use of a partionlcss pump region such as pump region 2i) shown by FIGURE 1, since the axial component fa imparts a desired velocity V to the conducting liquid and results in axial liquid flow through the pump region under pump iriduc-cu pr ssures. The forces, such as force F, that are impressed upon the liquid metal in the pump annulus 20 ot` FIGURE l move or pump the liquid metal from the inlet port 25 to the outlet port 26. The movement of the liquid meta in the pump annulus 2i) will continually "ub or liush the annulus of any dross or slag accumul: on therein. Whip or runout chaructcriC s of the Clepcnding pump components also are minimized oy thc energizatioii of the i ald winding 4'! which assists in Obtaining virtually vibrationlcss running characteristics of the rotating pump Components. Por example, in one test run, .004 inch runout or variance from the vertical axis of rotation was observed for the rotating pump componcnts without field cnergization. When thc field winding 7 was encrgizxl, the magnetic field set up by the helical rotor geometry significantly reduced the rcnout to .OS2 inch.

The directionalizcd laminar flow of the molten metal under the pump induced pressures created by the described electromagnetic forces provides a rclati '-ly calm liquid tlow from the outlet port 26 with a minimum of turbulence. While the outlet port 21S is tangentially directed to the outlet region 22 and contributes to the calm flow, the tangential attitude is not critical to the operation of the pump system ofthe invention.

The introduction of the pumped metal from the discharge or outlet port 25 to a closed conduit 27 for transfer to another location also reduces the probability of additional gas adsorption and related dross accumulation by the melt. If necessary, the Conduit 27 may bc suitably insulated or heated to minimize temperature losses in the liquid metal during transfer. Thus, the pumped metal fiows under pump induced pressure at a near optimum pouring temperature without requiring additional heating in a subsequent holding or pouring ladle, not shown. The liquid metal also can beA pumped at the near optimum pouring temperature without requiring prior overheating in the melt body to compensate for subsequent temperature losses during transfer such as those experienced in the known prior art pump systems.

Accurate successive or continuous flow of liquid metal under pump induced pressures is achieved by control of either the drive motor 35, the energization of the eld winding 47, or both, so that measured flow and instantaneous stoppage of the calm liquid flow from the pump system of the invention is possible. For example, in one pump system formed in accordance with the invention, a 25 ampere field current was maintained in the eld winding 47 when the drive motor 35 was stopped. A prior 3000 gallons per minute discharge ow from the pump system rapidly decreased to zero flow with a time constant of three seconds. The field current was turned off only after the discharge flow of liquid metal had terminated.

Known gravity or syphon transfer arrangements require approximately one hour to transfer 40,00() pounds of a liquid metal, such as aluminum, with no assurance of a calm metal ow. One of my electromagnetic pump systems pumps 500 gallons per minute and transfers 600,- 000 pounds of aluminum in one hour; the transfer being accomplished with a calm laminar ow and under pump induced pressure against' the effects of gravity by use of the previously described electromagnetic forces.

The electromagnetic pump system particularly shown by FIGURES 1 and 2 will pump 262() gallons per minute at a developed pressure of 31.5 p.s.i. when the helical rotor 40 is driven at 374 r.p.m. with a direct current input to the field winding 47 of 28 amperes total at 200 volts. When the rotor is driven at constant speed, the discharge flow from the pump may be varied by a field rheostat in series with the direct current power source for the field winding 47 to obtain a smooth, stepless variation of iow and pressure.

A simple reversal of the drive motor 35 provides reverse travel of liquid in the pump region or annulus 20 to rapidly clean the discharge port 26, conduit 27, and related flow passages of liquid metal. This avoids solidication of liquid metal in the tlow passages during periods when no liquid flow is desired.

FIGURES 4 and 5 show another form of the electromagnetic interaction pump system of the present invention. The principle of operation is similar to the pump system shown by FIGURES l and 2. The pump system shown by FIGURES 4 and 5 operates in a partly submerged position in a liquid metai pool or body of melt 65. The melt 65 may be contained by suitable bricks 66 or other suitable structure common to foundry practice.

FIGURE 4 shows one form of a structural beam arrangement 68 positioned generally above the melt 65 and bearing upon the bricks 66. Other support arrangements are also contemplated to be within the concept of the pump system being described and the arrangement 68 shown by FIGURES 4 and 5 is not critical. A support ring 70 is retained by the beam arrangement 68 and engages a radially extending flange portion 72 of an outer channel portion 73. The outer portion 73 is spaced from and circumjacent to an inner Crucible portion 75 to develop a pump region or annulus 76 therebetween.

The outer and inner portions 73 and 75 respectively are shown by FIGURE 5 as an integral unit either preformed from metal or a suitable refractory material such as those materials previously described. It is again contemplated that for ease of construction and assembly the portions 73 and 75 can be sectionalizcd and built up into the general configuration as shown by FIGURE 5. If

desired, suitable spacer members, not shown, can be provided between the outer and inner portions.

The structural beam arrangement 63 also supports a prime mover, such as an electric motor 78, with a depending rotor shaft 79 connected thereto. A field wound helical rotor 80, similar in all structural aspects to the field wound helical rotor 40 shown by FIGURES 1 and 2, is secured to or integrally formed with the rotor shaft 79. The helical rotor S0 depends into the inner Crucible portion 75 so that the pump annulus 76 is generally circumjacent to the rotor.

A magnetic structure 84provides a return path for the magnetic ux field set up by the magnetic rotor. The magnetic structure 84 is positioned within the outer channel portion 73 and is preferably formed from a plurality of mild steel laminations. The magnetic structure 84 may also be supported from the beam arrangement 68 to reduce the loading on the outer channel portion 73, particularly when the channel portion is formed from a refractory material. Secondary insulating barriers 86 and 87, formed from asbestos or the like, are positioned between the magnetic structure 84 and the walls of the outer portion 73 to reduce the heat transfer from the melt .65 t0 the magnetic structure 84. A cooling medium, such as air, is introduced to the magnetic structure 84 through an inlet conduit 90 to maintain the laminates below their Curie temperature. The cooling air passes from the inlet conduit 90 to a plenum region or tube 91 and then exhausts from the magnetic structure 84 through a plurality of cricumferentially spaced ducts, such as duct 92. It is contemplated that additional heat transfer barriers, similar to heat barriers 86 and 87, may be positioned within the inner crucible portion 75 between the periphery of the helical rotor Si! and the walls of the inner portion 75.

The pump annulus 76 is open to the melt 65 on a plane that is suitably spaced from the hearth or pot bottom 94. Ingress of molten or liquid metal to the pump section 76 during operation of the pump system, shown by FIG- URES 4 and 5, develop-s a gentle swirling or stirring action in the melt 65 which assists in maintaining a hornogenous melt and aids in the escape of absorbed gases in the melt without rupture of the protective oxide skin on the melt surface.

Operatively, the electromagnetic pump system shown by FIGURES 4 and 5 develops a pumping action similar to that previously described with regard to the pump system shown by FIGURES 1 and 2. The electromagnetic forces developed within the pump section 76 upon the electrically conductive liquid therein are in accordance with those forces previously described and effect the lifting and conveying of the liquid metal to an outlet or discharge conduit 97.

FIGURE 6 shows yet another modification of the electromagnetic interaction pump system of the invention. Again the theory and principle of operation is similar to that previously described with regard to the pump systems of my invention as shown by FIG- URES 1-5.

The helical rotor is positioned generally circumjacent to a pump region or annulus 102 as shown by FIGURE 6. A magnetic structure 103, structurally similar to those previously described, is positioned within an insulating core member 104 and provides a flux return path means. The core member 104 is centrally positioned within the volume defined by the pump annulus 102 by a plurality of spacer members similar to spacer member 105.

An external drive means, such as an electric motor 110, rotates the helical rotor 100 through a suitable power transmission means, such as the intermeshing

spur gear arrangements

112 and 113. The power transmission gear arrangements are not critical to the operation of the inveniton and are shown only as an illustration of suitable arrangements,

A lield winding 120 threaded on the skewed poles of the helical rotor 100 is energized from an external direct current power supply, not shown, through well-known leads and brushes cooperating with suitable slip rings 122. When the eld winding 12) is energized and the helical rotor 13S driven by the drive motor 1li), the electrically conductive liquid in the pump annulus $.02 moves from an inlet port 125 to an outlet port 126 by the forces imparted in the pump annuius.

The electromagnetic pump system shown by FIGURE 6 is particularly adapted for operation in a horizontal orientaiton. However, it is contemplated that the pump system can be use in a generally vertical orientation such as shown for the pump systems of FIGURES 1 and 5.

The .elical rotor electromagnetic pump systems, as shown and described, offers distinct advantages over known mechanical pump systems and other electr magnetic pump systems, i.e. induction and conduction pumps. The helical rotor pump system 'nas (l) no moving parts in contact with the liquid being pumped, (2) no seals or stuffing boxes required, and (3) operability in either horizontal or ver "al orientati n.

In addition, the helical rotor pump system of the invention offers several unique features: flow rates are easily varied; highly efficient operation; reduced entrance losses so that the pump system can operate at low net positive suction with cavitation; large running clearances between the rot. ting pump components and the pump region components; concentrated fie'd winding sets up a strong magnetic field across a wide gap which makes it possible to use a thick-walled pump channel or region; operational tieni' since the rotating pump compoen.s are not secured to the pump r on components; and no capacitors are required for power factor correction since direct current is preferably used to set up the magnetic field.

As will be evidenced from the certain aspects of the invencn are not limited to the particular details of construction as illustrated. While the Source of magnetic flux is shown by FlGURES l-6 as a helical rotor with a field wi 'ug suitably energized, the magnetic flux can be devclopd by suitably arranged permanent magnets sltcwed to form a he.ical rotor, or by a combination of elecL magnets and permanent magnets. A skewed or helical psrtnanent magnet rotor as a source oi' magnetic ilus/ ticulsr use in small pump systems to develop the magnetic fo ces on the liquid being pumped. it is contemplated that ohcr modications and 3 lied in the art. Accordingiy, it is intended that ta: appended claims shall cover such modifications and applications that do not depart from the true spirit and scope of the invention.

Having described my invention, what I claim and desire to secure by Letters Patent of the United States is:

i. An electromagnetic pump system for pumping electrically coductive liquids comprising:

(a) first and second generally cup-shaped members,

(b) a rim portion on said first cup-shaped member cooperating with a rim portion on said second cupshaped member to nest said first member within said second member in a spaced apart relationship to each other,

(c) a pump region developed between said first and second members,

(d) at least one inlet port to said pump region in said second member,

(e) at least one outlet port form said pump region,

(f)` a field wound helical rotor rotatably positioned within said first cup-shaped member and spaced therefrom to define a coolant flow path,

(g) support means for said helical rotor including a bearing arrangement removed from said lirst cupshaped member,

(h) flux return path means circumjacent to said pump region,

foregoing description,

(i) cooling means for said ux return path,

(j) means electrically connecting said field wound rotor to a power source to set up a substantially radial magnetic flux field across said pump region distributed in at least one helical curve about said v rotor, and

(k) drive means to rotate said helical rotor so that the magnetic field induces eddy-currents in a conductive liquid in said region which flow in paths that conform with the helical geometry of said rotor means and interact with the magnetic field to impart pumping forces on the liquid.

2. The pump system of claim 1 in which said pump region is an annulus.

3. The pump system of claim 1 in which said cupshaped members are formed from a suitable insulating material.

4. An electromagnetic pump system for pumping electrically conductive liquids comprising:

(a) an inner Crucible portion,

(b) an outer channel portion generally circumjacent to said inner portion and spaced therefrom,

(c) a pump region developed between said inner and outer portions,

(d) at least one outlet port from said pump region,

(e) a field wound helical rotor rotatably positioned within said inner Crucible portion and spaced therefrom to develop a coolant ow path,

(f) support means for said helical rotor and said inner and outer portions including a bearing arrangement removed from said inner and outer portions,

(g) flux return path means positioned within said outer channel portion,

(h) cooling means for said flux return path,

(i) means electrically connecting said field wound rotor to a power source to set up a substantially radial magnetic flux fluid across said pump region distributed in at least one helical curve about said rotor, and

(j) drive means to rotate said helical rotor so that the magnetic field induces eddy-currents in a conductive liquid in said region which flow in paths that conform with the helical geometry of said rotor means and interact with the magnetic field to im part pumping forces on the liquid.

5. The pump system of claim 4 in which said pump region is an annulus.

6. The pump system of claim 4 in which said cupshaped members are formed from a suitable insulating material.

7. An electromagnetic pump system for pumping electrically conductive liquids comprising:

(a) a central core member, l

(b) flux return path means positioned within core member,

(c) a field wound helical rotor rotatably positioned circumjacent to said core,

(d) a pump region juxtaposed between said helical rotor and said flux return means,

(e) at least one inlet and outlet port from said pump region,

(f) means electrically connecting said field wound rotor to a power source to set up a magnetic flux eld across said pump region, and

(g) drive means to rotate said helical rotor so that the magnetic field induces eddy-currents in a conductive liquid in said region which flow in paths that conform with the helical geometry of said rotor means and interact with the magnetic field to impart pumping forces on the liquid.

said

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Newcomb 103-1 Bender 103-1 Donelian 103-1 Godold 103-1 Godbold 103-1 Bowlus 103--1 Spagnoletti 103-1 Richter 103-1 Swanson 13-33 Dickson 13--33 Findlay 103-1 Baker 103-1 Yevck 103--1 FOREIGN PATENTS Great Britain.

LAURENCE V. EFNER, Primary Examiner.

Claims

1. AN ELECTROMAGNETIC PUMP SYSTEM FOR PUMPING ELECTRICALLY CONDUCTIVE LIQUIDS COMPRISING: (A) FIRST AND SECOND GENERALLY CUP-SHAPED MEMBERS, (B) A RIM PORTION ON SAID FIRST CUP-SHAPED MEMBER COOPERATING WITH A RIM PORTION ON SAID SECOND CUPSHAPED MEMBER TO NEST SAID FIST MEMBER WITHIN SAID SECOND MEMBER IN A SPACED APART RELATIONSHIP TO EACH OTHER, (C) A PUMP REGION DEVELOPED BETWEEN SAID FIRST AND SECOND MEMBERS, (D) AT LEAST ONE INLET PORT TO SAID PUMP REGION IN SAID SECOND MEMBER, (E) AT LEAST ONE OUTLET PORT FORM SAID PUMP REGION, (F) A FIELD WOUND HELICAL ROTOR ROTATABLY POSITIONED WITHIN SAID FIRST CUP-SHAPED MEMBER AND SPACED THEREFROM TO DEFINE A COOLANT FLOW PATH, (G) SUPPORT MEANS FOR SAID HELICAL ROTOR INCLUDING A BEARING ARRANGEMENT REMOVED FROM SAID FIRST CUPSHAPED MEMBER,