US2981193A - Electromagnetic pump - Google Patents

Description

FIP8502 KR 29981195 April 25, 1961 w. L. CARLSON, JR 2,981,193

ELECTROMAGNETIC PUMP Filed Oct. 9, 195 7 2 Sheets-Sheet 1 \llllllllllHllllHl lllllllllllfl Apnl 25, 1961 w. L. CARLSON, JR 2,931,193

ELECTROMAGNETIC PUMP Filed Oct. 9, 1957 2 Sheets-Sheet 2 INVENTOR.

1 BY Z @w ATTORNEY 3 WILLIAM L. CARLSON, JR.

United ELECTROMAGNETIC PUMP Filed Oct. 9, 1957, Ser. No. 689,116

7 Claims. (Cl. 103-1) The present invention is directed to an electromagnetic conductive fluid type of pump, and more specifically is directed to a pump construction capable of effectively handling highly corrosive, conductive liquid metals.

The Faraday, or conductive type of electromagnetic conductive fluid pump has been known and in use for many years. Originally this type of pump was utilized to move noncorrosive liquid metals such as mercury and mercury compounds. When this type of pump was applied to mercury the materials used in the construction of the pumping channel or gap were relatively easy to-utilize, as mercury is a comparatively inactive type of fluid and could be easily contained. In practice the pumping channel for handling mercury and mercury compounds usually consisted of two metallic electrodes encased in, or entering the walls of an insulated tube. This tube could be glass, plastic, or other conventional types of insulating material. When the conductive type of electromagnetic conductive fluid pump is applied to more active or corrosive liquid metals such as sodium, potassium, or sodiumpotassium compounds it becomes necessary to eliminate all but a limited number of materials from contact with the corrosive fluid. It also becomes essential that the pump be hermetically sealed. For the most part, the only practical materials compatible with sodium, potassium or sodium-potassium compounds are certain forms of steel, aluminum, and copper.

Since the conduction type of electromagnetic pump operates on the principle of a current flowing through a conductive fluid in a perpendicular relationship to a magnetic field, it becomes apparent that certain problems would be involved in containing the corrosive liquid metal or fluid in a chamber made entirely of metals. In the prior art it was determined that by constructing a pumping channel having four walls of metal, two of which were of high electrical resistance, it was possible to build an electromagnetic conductive fluid pump which was quite eflicient. The theory behind the operation of this type of pump is that the current flowing through the conductive'liquid metal is much greater in percentage than that which will flow through a high resistance steel wall of thin cross section. In the construction of relatively large size conductive fluid or liquid metal pumps it was relatively simple to construct a pumping channel having two copper walls and two walls of a high resistance steel welded or joined at their edges to form the pumping chamber. This type of arrangement provided the very desirable features of mechanical strength as well as the necessary hermetic seal to effectively contain the more corrosive liquid metals. This construction however, does not lend itself to application in conductive liquid metal pumps having exceedingly small pumping channels. As the size of the pumping channel is decreased the mechanical problems of welding or joining different metals to form a rectangular channel become progressively more diflicult. In an efliort to overcome the difliculties of fabricating a pumping channel of four separate pieces of material the next step in evolution of smaller sized electromagnetic tates I atent conductive fluid pumps was to utilize a high resistance stainless steel type tube which was flattened to a rectangular cross section. Copper electrodes were then introduced into the walls of the tubing or attached directly to the exterior surfaces thereof. This construction while some what difiicult in smaller sizes is physically possible and commercially feasible.

It has now become desirable to build electromagnetic conductive fluid pumps having a cross section of their pumping channel of approximately of an inch by of an inch. It will be appreciated that a pumping channel of of an inch in height does not readily lend itself to either of the previously described methods of construction. Attempts to fabricate pumping channels of this smaller size from flattened tubing prove to be impractical, at least as far as production quantities is concerned. It became apparent that an entirely new approach would be necessary to build a pumping channel for an electromagnetic conductive fluid pump which had the small cross section desired, as well as the hermetic seal and all metal construction found to be desirable when used with corrosive liquid metals. The present invention is directed to a construction for a liquid metal pump channel which can be readily built in production quantities and which retains the desirable features developed in the prior art.

It is an object of the present invention to disclose a novel construction of an exceedingly small pumping channel for an electromagnetic conductive fluid pump wherein the current supplied to the channel for pumping the fluid passes through the fluid itself as a conductor leading to the enclosed electrodes.

It is a further object of the present invention to disclose a construction for a pumping channel which is rugged in nature and therefore capable of use in commercial applications.

A still further object of the present invention is to disclose a hermetically sealed conductive fluid pumping channel of an all metal nature.

Yet another object of the present invention is to disclose a liquid metal pump in which the current supplied to the pumping channel is conducted to the electrodes through a mechanically large area and a segment of the conductive fluid itself.

Yet a further object of the present invention is to disclose the construction of a liquid metal pump channel that is built up entirely separate from the main pump structure so that the conductive fluid channel can be tested under pressure prior to the assembly of the entire pump.

These and other objects of the present invention will become apparent when the two sheets of drawings accompanying the present application are fully considered, wherein;

Figures 1, 2, and 3 are a top view, end view, and side view respectively of an electromagnetic liquid metal pump substantially complete, except for external supporting structure;

Figure 4 is a cross section along line 44 of Figure 1 of a pumping channel perpendicular to the line of flow of the conductive fluid being pumped;

Figure 5 is an elevation of the pumping channel along line 5-5 of Figure 4;

Figure 6 is a cross section of the pumping channel along line 6-6 of Figure 4, and;

Figures 7 and 8 are cross sections of a pumping channel in a modified form and correspond to Figures 4 and 6 of the first embodiment.

In Figures 1 through 3 there is shown an entire electromagnetic conductive fluid pump, with the exception of the mechanical support means for the different sections of the unit. The pump has a primary energizing ,coil 10 adapted to be connected to any convenient source of alternating current. Associated with coil 10 is a laminated structure 11 forming a conventional double window transformer and being held together by bolt means 12. Encircling coil 10 and passing through the laminated structure 11 is a secondary current strap 14, which is formed in the shape of a U and which is made of a good current conducting material such as copper or aluminum. When the coil 10 is energized the secondary current strap 14 provides a source of very high current at an exceedingly low voltage. This current is available across the ends 15 and 16 of the secondary current strap 14 and is utilized in the electromagnetic pump manifold assembly generally shown at 17. The details of the manifold assembly 17 are shown in Figures 4 through 8 in two separate embodiments. It should be further understood that the manifold assembly 17 could be utilized with any source of high electric current at a low potential and that in some cases this high current, low potential could be of a direct current nature. Since the secondary current strap 14 carries a high current at a very low potential it is obvious that it will require very little in the way of insulation to prevent a current trans fer from the strap 14 to other parts of the pumping device. As this is the case, the insulating materials have not been shown for clarity sake, but it is understood that the strap 14 is properly insulated whenever necessary.

Near the ends 15 and 16 of the secondary current strap 14 there is placed a second stack of laminations 20 made up of two F- shaped laminations 21 and 22. The F- shaped laminations 21 and 22 when pressed together form a double Window magnetic circuit having an air gap 23. The air gap 23 can best be seen in Figures 2 and 4. The laminations 21 and 22 are positioned in the proper relationship on the secondary current strap 14 and then the laminations are joined by welds at 24 and 25 to hold the two F- shaped laminations 21 and 22 into a unitary laminated structure 20. Before this assembly procedure is undertaken two energizing coils 26 and 27 are slipped onto the center legs of the laminations 21 and 22. When the coils 26 and 27 are energized with the proper phase and voltage, a magnetic field is established in the laminated core 20 so as to provide a concentrated magnetic field across the air gap 23. This magnetic field interacts with the current present in the secondary current strap 14 in a manner previously described and provides the pumping force to propel a conductive fluid such as a liquid metal within the pumping manifold assembly 17. The fluid path through the manifold assembly 17 will be described in detail below.

The pumping manifold assembly 17 is supported between the ends 15 and 16 of the secondary current strap 14. This can best be seen in Figures 4 and 8, wherein two embodiments of the manifold assembly are shown. Attached to strap end 15 is a conductive mounting block 30. A similar block 31 is attached to the strap end 16. The joint between the strap ends 15 and 16 and the conductive mounting blocks 30 and 31 can be welded or soldered to form a good electrical contact, or the blocks 30 and 31 can be formed directly from the secondary current strap 14. The mounting blocks 30 and 31 in turn support two conductive manifolds or reservoirs 32 and 33. The manifolds 32 and 33 are tubular in shape as shown in Figures and 6. The ends 34, 35, 36, and 37, of the manifolds 32 and 33 are sealed in a fluid tight relationship by welding or brazing manifold caps 41, 42, 43, and 44, thereon. The manifold caps 41 through 44 form completely fluid tight ends for the manifolds 32 and 33 and also provide a mounting means for tubes used to conduct the flow of the conductive fluid. More specifically, tubes 45 and 46 are shown connected into and through the manifold end caps 42 and 44. The connections between the tubes 45 and 46 and the end caps 42 and 44 can be made in any convenient manner as long as the joints are fluid tight.

The manifolds 32 and 33 each have lengthwise openings 50 and 51 extending substantially from end cap to end cap along one side of each of the manifolds. The openings 50 and 51 are formed by bending the walls of the manifolds 32 and 33 back in a curved manner to form lips 52. The lips 52 perform functions which will become apparent later in the description of the assembly of the device.

A duct, generally shown at 54, connects the manifolds 32 and 33 by passing through the openings 50 and 51 of each of the manifolds. The duct 54 is formed of a very thin sheet of high electrical resistance material. This material in the preferred embodiment is a high electrical resistance type of steel which is commercially available in sheet form of approximately of an inch in thickness. The duct 54 is formed by folding a sheet of the high electrical resistance material at 55 and welding its free or open edge at 56. By bending a sheet of material and welding it at 56 a channel or duct 54 is formed having two openings 57 and 58 which would be long thin rectangles if viewed in section. The ends of duct 54 can be flared out at 59 prior to insertion into openings 50 and 51 and placement of end caps 41 through 44. This provides a guide to locate manifolds 32 and 33 during assembly. Prior to the insertion of the duct 54 into the manifolds 32 and 33 two electrodes 60 and 61 are inserted into the open ends of the duct 54. The electrodes 6t and 61 are formed of a high electrical conductivity material such as copper and are generally rectangular in shape. The electrodes 60 and 61 are formed of a thin material as compared to their surface area as seen in Figures 4 and 6. Each of the electrodes 60 and 61 have a small offset 62 such that when the electrodes 60 and 61 are inserted into the duct 54, the electrodes can be brought to an aligned position defining a gap or channel 63 between the edge 64 of electrodes 60 and edge 65 of electrode 61. The offset 62 of the electrodes 60 and 61 thus make it easily possible to align the electrodes 60 and 61 so that the channel 63 is substantially uniform in width at approximately of an inch.

Each electrode 60 and 61 further has a channel 66 and 67 which terminates in a larger opening 70 and 71 in each of the electrodes 60 and 61 respectively. As can be seen in Figure 6, a complete path or channel is formed from the opening 70 through the channel 66 into the end of the channel 63 to the remote end of the electrodes 60 and 61 where the channel 67 joins the opening 71. The passage just described is the fluid flow path through the manifold assembly generally shown at 17. At the edges 72 and 73 of the duct 54 there can be seen an opening through the hole 70 and 71 into the center of the manifolds 32 and 33 and therefore it becomes apparent that any fluid contained in the manifolds 32 and 33 can easily flow between the manifolds whenever a pumping pressure exists. A complete, typical fluid flow path through the manifold assembly 17 would be from the pipe 45 into the manifold end cap 42 and thence into the mani fold 32. From the manifold 32 the fluid would flow through the opening 70 outside of the edge 72 of the duct 54. From the opening 70 the fluid flows into chan' nel 66 and thence to channel 63 and thereby passes to the opposite end of the channel 63. At the opposite end of the channel 63 the fluid passes into the channel 67 and thence past the edge 73 of the duct 54 into the hole 71. The hole 71 transmits the fluid into the manifold 33 and then to the manifold cap 44 where it passes to the outlet tube 46. It is obvious that the fluid path from the tubes 45 and 46 is identical regardless of direction of flow and therefore it makes no difference which of the tubes 45 or 46 is used as the inlet or outlet for the device.

In order to properly seal the manifolds 32 and 33 to the duct 54 in a fluid tight relationship the lips 52 have been provided on the openings 50 and 51 in each of the manifolds 32 and 33. The order of assembly of this unit is to insert the electrodes 60 and 61 into the prefabricated duct 54. The duct 54 with the inserted electrodes 60 and 61 are then inserted into the manifolds 32 and 33 through the openings 50 and 51 between the lips 52 and the manifolds 32 and 33; The lips 52 of the manifolds 32 and 33 are then pressed tightly down against the walls of the duct 54 which in turn tightly closes the wall of the duct 54 against the surface ofelectrodes 60 and 61. This does not deform lips 52 in any way. This joint is under a great enough pressure so that a fluid tight relationship exists between the inside surface of the duct 54 and the surfaces of electrodes 60 and 61 except at the channels 66 and 67. The electrodes 60 and 61 being separated in the duct 54 by the offset 62 thereby provide a positioning means for the alignment of the manifolds 32 and 33' as well as providing a fluid coupling means. -.After the manifolds have been clamped by the lips 52 to the outer walls of the'duct 54 the space between the outer walls of the duct 54 are filled with silver solder, shown at 75. End caps 41 to 44 are then soldered into place. The solder 75 completely seals the lip 52 of the manifolds 32 and 33 along the entire surface of the duct 54 and also completely close the openings 50 and 51 in the manifolds 32 and 33 to provide a hermetically sealed unit. Once the unit shown in Figure 6 has been scaled by the addition of silver solder 75 a complete, exceedingly rigid and strong manifold pump assembly has been formed. This assembly is entirely separate from the balance of the pumping device and is attached to the secondary current strap 14 as previously described. By providing a pumping assembly of this nature it is possible to fabricate the fluid flow section of the pump entirely separate from the remaining parts and thereby simplify the assembly procedure. This separate unit also can be put through leakage and other types of tests prior to its assembly in a finished unit and thereby reduce manufacturing costs by the elimination of defective units prior to their final assembly steps. This is different from units fabricated in a conventional fashion in that the more conventional units generally utilize construction techniques wherein the entire pump must be assembled before the pumping channel, in this case channel 63, has been built up to a point where it is fluid tight and can be tested.

The manifold assembly 17, when it is joined by the conductive mounting brackets 30 and 31 to the ends 15 and 16 of the secondary current strap 14 provides the pumping channel when the following relationship is established. The coils 10, 26, and 27, being properly energized supply a high current at low voltage between the ends 15 and 16 of the secondary current strap as well as providing a high concentration of magnetic flux across the poles 21 and 22. As can be seen in Figure 4, the concentration of flux occurs across and perpendicular to the channel 63. At the same time a complete current path is formed between the ends of the secondary strap 15 and 16 by means of the conducting mounting brackets 30 and 31 and the manifold assembly 17. More specifically a current path exists between the end 15 of the secondary current strap into the conductive mounting bracket and thence through the wall of manifold 32. The current flows from the wall of manifold 32 into the conductive fluid contained within the manifold and then to the electrode 60. Once reaching the electrode 60 the current is free to flow to the edge 64 of the electrode 60 where it comes in contact with a channel of conductive fluid defined by the channel 63. The current then flows across the channel 63 to electrode 61 along its entire edge 65. The current then passes again from electrode 61 to the conductive fluid contained in the manifold 33 and thence to the wall of manifold 33 to the conductive mounting bracket 31. This allows the current then to return to the end 16 of the secondary current strap 14 to complete a secondary circuit for the coil and core 11. It will thus be seen that a current flows at right angles across the channel 63 to the magnetic field which occurs between the poles 21 and 22. The interaction of the electric current and the magnetic field cause a pumping pressure to be created along the length of channel '63 thereby moving fluid from channel 66 to channel 67. This in turn moves the fluid through the entire manifold assembly 17 from the inlet to outlet tubes 45 and 46.

With the arrangement shown a complete electromagnetic conductive fluid pump has been described wherein a pumping channel 63 is formed having dimensions of approximately by of an inch. It is appreciated that the fabrication of a channel, which is fluid tight and capable of handling the fluids in the manner described, is very unusual primarily in that the current conduction path through the device is by means of the electrodes and the conductive fluid in the manifolds themselves. This path is then completed in a more conventional nature between the ends 15 and 16 of the secondary current strap 14.

A second embodiment shown in Figures 7 and 8 utilizes substantially all of the same principles, but has a slightly different manner of fabricating the duct 54 and its associated electrodes. In Figures 7 and 8 the duct 54 is fabricated once again by folding a sheet of high electrical resistance steel. Prior to forming the weld 56 however, the electrodes and 81 are placed on one surface 82 of the duct 54. Two pair of holes 83 and 84 are stamped into each of the electrodes 80 and 81 in such a manner to form a flange or lip 85. This flange or lip (shown dotted in Figure 7) is bent over behind the holes and locks the electrodes 80 and 81 into a fixed relationship to the duct 54. Channels 66 and 67 lead from the holes 83 to the central channel or gap 63, in the same manner as described in connection with Figure 6. It will thus be seen that the conductive fluid contained in the manifolds 32 and 33 can flow through the holes 83, into the channels 66 and 67 to reach the channel in the same manner as previously described. With the presently described arrangement the electrodes 80 and 81 can be accurately positioned within the duct prior to its complete assembly and thereby the exact relationship can be visually checked and maintained. After the electrodes 80 and 81 are properly placed by the operation previously mentioned, the weld 56 is made in the duct 54 thereby closing the lengthwise edge along the Weld 56. This duct and electrode assembly is then utilized as previously described by soldering the duct containing the electrodes into the manifolds 32 and 33. As further shown in Figure 7 the tubes 45 and 46 can be brought into the manifolds 32 and 33 at opposite ends of the manifold assembly 17. The selection of the location of tubes 45 and 46 is thus obviously a matter of convenience and both tubes can be brought in at either end of the assembly 17 or from opposite ends of the assembly 17 without departing from the nature of the present invention.

The two embodiments which have been described in detail are illustrative only of the many ways in which a pumping channel of exceedingly small dimension can be fabricated in a hermetically sealed manner. This channel utilizes the principle of conduction of the current from the current source through the manifo d assembly by means of the conductive walls of the manifolds themselves as well as through the conductive fluid to the actual electrodes which form the walls of the pumping channel. With this arrangement it is possible to easily connect a large amount of electric current to an exceedingly small electrode by means of the conductive surface area utilized in the device. This arrangement further provides for a hermetically sealed unit which is very rigid in construction and which is capable of being assembled entirely separate from the balance of the pump. This allows for manufacturing economies in that the manifold assembly can be pretested to determine if it is exactly correct prior to its assembly in the balance of the pump unit. In this way the rejection rate of the finished pump can be kept to an absolute minimum. While two preferred embodiments have been shown in detail the applicant wishes it clearly understood that they are illustrative only and that 7 many modifications within the scope of the present invention will become apparent to those skilled in the art. The applicant therefore wishes to be limited in his invention to the appended claims only.

I claim as my invention:

1. A pump of the class described wherein a liquid metal is propelled by, and mutually perpendicular to, an electric current and a magnetic field to which the liquid metal is subjected: an inlet manifold and an outlet manifold of tubular copper in parallel spaced relationship; a flat duct of high electrical resistance metal intermediate to and joining said manifolds in a fluid tight relationship; a pair of copper electrodes inserted in said duct and each electrode extending into one of said manifolds; said electrodes further being separated in a parallel spaced relationship in said duct to form a pumping channel; and each said electrode having passage means joining one end of the channel and a single said manifold; said manifolds and said electrodes defining a liquid metal flow path through said pump; said field being perpendicular to said duct while said current passes through said manifolds and said liquid metal to said electrodes toreact with the field in said channel to propel said liquid metal in the channel from said inlet manifold to said outlet manifold.

2. A pump of the class described wherein a liquid' metal is propelled by, and mutually perpendicular to, an electric current and a magnetic field to which the liquid metal is subjected: an inlet manifold and an outlet manifold of electrically conductive metal; a flat duct of high electrical resistance metal joining said manifolds in a fluid tight relationship; a pair of electrodes inserted insaid duct and each electrode extending into one of said manifolds; said electrodes further being separated in a parallel spaced relationship in said duct to form a pumping channel; and each said electrode having passage means manifolds and said liquid metal to said electrodes to re-' act with the field in said channel to propel said liquid metal in the channel.

3. A pump of the class described wherein a liquid metal is propelled by, and mutually perpendicular to, an

electric current and a magnetic field to which the liquid metal is subjected: an inlet manifold and an outlet manifold of electrically conductive material; a flat duct of high electrical resistance material joining said manifolds in a fluid tight relationship; a pair of electrodes inserted in said duct; said electrodes further being separated in a parallel spaced relationship in said duct to form a pumping channel; and each said electrode having passage means joining one end of the channel and a single said manifold; said manifolds and said electrodes defining a liquid metal flow path through said pump; said field being perpendicular to said duct while said current passes through said manifolds and said liquid metal to said electrodes to react with the field in said channel to propel said liquid metal in the channel.

4. A pump of the class described wherein a conductive fluid is propelled by, and mutually perpendicular to, an electric current and a magnetic field to which the fluid is subjected: an inlet manifold and an outlet manifold of electrically conductive material; a flat duct of high electrical resistance material joining said manifolds in a fluid tight relationship; a pair of electrodes inserted in said duct; said electrodes further being separated in a parallel spaced relationship in said duct to form a pumping channel; and each said electrode having passage means joining one end of the channel and a single said manifold; said manifolds and said electrodes defining a fluid flow path through said pump, said field being perpendicular to said duct while said current passes through said manifolds and said fluid to said electrodes to react with the field in said channel to propel said fluid in the channel.

5. A pump of the class described wherein a conductive fluid is propelled by a relationship of an electric current and a magnetic field angularly disposed to each other and to the direction of flow of said fluid: an inlet manifold and an outlet manifold of conductive material in parallel spaced relationship; a flat duct intermediate to and joining said manifolds in a fluid tight relationship;

'a pair of conductive electrodes inserted in said duct and each electrode extending into one of said manifolds; said electrodes further being separated in a parallel spaced relationship in said duct to form a pumping channel; and each said electrode having passage means joining one end of the channel and a single said manifold; said manifolds and said electrodes defining a fluid fiow path through said pump.

6. A pump of the class described wherein a liquid f metal is propelled by a relationship of an electric current and a magnetic field angularly disposed to each other and to the direction of flow of said liquid metal: an inlet manifold and an outlet manifold of conductive material in parallel spaced relationship; a flat duct of a high resistance metal intermediate to and joining said manifolds in a fluid tight relationship; a pair of conductive electrodes inserted in said duct and each electrode extending into one of said manifolds; said electrodes further being separated in a parallel spaced relationship in :said duct to form a pumping channel; and each said electrode having passage means joining one end of the channel and a single said manifold; said manifolds and said electrodes defining a fluid flow path through said pump.

7. In a device of the class described wherein a conductive fluid is flowing with a relationship of an electric current and a magnetic field angularly disposed to each other and to the direction of flow of said fluid: an inlet 'manifold and an outlet manifold of electrically conductive material; a flat duct of high electrical resistance ma terial joining said manifolds in a fluid-tight relationship; a pair of electrodes inserted in said duct; said electrodes further being separated in a parallel spaced relationship in said duct to form a channel; and each said electrode having passage means joining one end of the channel and a single said manifold; said manifolds and said electrodes defining a fluid flow path through said device; said field being perpendicular to said duct when said current is passing through said manifolds and said fluid in said channel.

References Cited in the file of this patent UNITED STATES PATENTS

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