US2978985A

US2978985A - Electromagnetic pumps

Info

Publication number: US2978985A
Application number: US525734A
Authority: US
Inventors: Nils E Lindenblad
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1955-08-01
Filing date: 1955-08-01
Publication date: 1961-04-11
Anticipated expiration: 1978-04-11

Description

FI P85 0 2 XR 2 19 78 @985 April 11, 1961 N. E. LINDENBLAD ELECTROMAGNETIC PUMPS Filed Aug. 1. 1955 H III I I I I I I I I I I I I 2 Sheets-Sheet 1 EXCHANGE DEV/0E HU /0 M/ZET [15a mo- MAG/V5770 PUMP INVENTOR. NILS E. LINDENBLAD ATTORNEY April 1961 N. E. LINDENBLAD 2,978,985

ELECTROMAGNETIC PUMPS Filed Aug. 1, 1955 2 Sheets-Shet 2 IN V EN TOR. N115 E. LINDENBLAD ATTORNEY ELECTROMAGNETIC PUMPS Filed Aug. 1, 1955, Ser. No. 525,734

6 Claims. (Cl. 103-1) The present invention relates to an improved electromagnetic pump, and is also concerned with a pumping system wherein a first liquid, which may be electromagnetically pumped, drives a second liquid.

Electromagnetic pumps are useful in pumping conductive fluids such as liquid metals. It may be desirable, however, to pump a nonconductive fluid electromagnetically. In a cooling system, for example, a nonconductive fluid such as water may be found more suitable as a heat transfer agent.

Some types of heretofore proposed electromagnetic pumps require provisions whereby conductive contact with the fluid is made. This is disadvantageous because contamination of contacts and resistive losses at the contacts may arise. Other types of electromagnetic pumps require rather complicated structures so that conductive fluid may be driven with a rotating magnetic field. The present invention provides an improved electromagnetic pump which eliminates the need for conductive contact with the fluid as well as the need for complex pump structures.

Briefly, an electromagnetic pump constructed according to the present invention includes an oblong closed loop with inlet and outlet ports for the passage of a conductive fluid to be pumped. The loop is magnetically coupled to a coil to which a source of alternating current is connected. A heavy alternating current is, therefore, electromagnetically induced in the fluid contained in the loop. Another alternating magnetic field that is transverse to the loop is provided near the outlet port. This last mentioned alternating magnetic field interacts with the magnetic field established by the current induced into the fluid contained in the loop and a resultant force is applied to the fluid which propels it through the outlet port. The pumped conductive fluid may be used as a primary driving fluid to pump, in turn, some other fluid such as a nonconductive coolant in a refrigerating system.

Known methods for pumping one fluid with another fluid have not been found suitable. For example, a conductive fluid, such as mercury, has not been successfully used as a primary drive fluid. In one known method, jets of the primary drive fluid must entrain the driven fluid. Since the friction between the primary drive fluid and the driven fluid is very small, this method has proven ineflicient. Another method consists of breaking up the flowing conductive fluid into sections in a tube, and allowing alternate sections of the driven liquid to be forced along by the weight and pressure of the conductive fluid. This method has provided only erratic pressures.

The present invention possesses, in addition to features pointed out above, the feature of obtaining a continuous flow of the driven fluid by providing a novel flow exchange device. In one illustrative form of the device, the conductive fluid, which may be pumped by the electromagnetic pump described above, is finely divided into droplets. The droplets are forced into a tube through which the driven fluid flows. This finely divided conductive fluid provides a rain of conductive fluid through the driven fluid. The driven fluid is dragged along by the conductive Patented Apr. 11, 1961 fluid. Therefore, the energy of the pumped conductive fluid is transferred to the driven fluid. This energy is measurable as a pressure increment applied to the driven fluid. The primary drive fluid may be easily separated from the driven fluid and recirculated through the electromagnetic pump. For ease in separating the fluids, a primary drive fluid may be selected which has a higher specific gravity than the driven fluid.

It is an object of the present invention to provide an improved electromagnetic pump having no moving parts.

It is a further object of the present invention to provide an improved electromagnetic pump in which conductive contact with the pump fluid is eliminated.

It is a still further object of the present invention to provide an improved electromagnetic pump which is free of structural complexities and which is more economical to make than former electromagnetic pumps.

It is another object of the present invention to provide an improved pumping system wherein a primary drive fluid exchanges its flow energy with another fluid and thereby applies a pressure increment thereto.

It is still another object of the present invention to provide an improved pumping system in which an electromagnetically pumped fluid drives another fluid.

It is still another object of the present invention to provide an improved pumping system wherein a conductive fluid exerts hydraulic pressure on, and thereby pumps, another fluid having a lower specific gravity.

Other objects and advantages of the present invention will, of course, become apparent and immediately suggest themselves to those skilled in the art to which the invention is directed from a reading of the following specification in connection with the accompanying drawing in which:

. Figure 1 is a diagrammatic showing of a pumping system provided by the present invention;

Figure 2 is a detailed view, partially in section, of one embodiment of the flow exchange device included in Figure 1;

Figure 3 is a sectional side view of an electromagnetic pump constructed in accordance with the present invention, the section being taken along the line 33 of Figure 4;

Figure 4 is a plan view, partially in section, of the electromagnetic pump illustrated in Figure 3, the section being taken along the line 44 in Figure 3; and

Figure 5 is a schematic diagram of the electrical circuit of the electromagnetic pump illustrated in Figures 3 and 4.

The block diagram of Figure 1 shows a pumping system provided by the present invention. The basic elements of this pumping system are an electromagnetic pump 10 and a flow exchange device 11. The electromagnetic pump 10 circulates a conductive fluid through the flow exchange device 11. The conductive fluid, which may be a liquid metal such as mercury, is pumped, in the direction indicated by the arrow, through an outlet port 43 thereon and through one of the pipes 12 which connects the electromagnetic pump 10 to the flow exchange device by way of the port 9. Another pipe 13, which is connected to the outlet port 20, receives the conductive fluid after it has passed through the flow exchange device 11, and is connected to the electromagnetic pump 10 which recirculates the fluid through an inlet port 42 thereon.

Another fluid circulates through the flow exchange device 11. It enters the flow exchange device 11 through an inlet pipe 14 and an inlet port 24 and leaves through an outlet port 22 and an outlet pipe 15. This fluid may be a non-conductive fluid, such as water, having a lower specific gravity than mercury which may be used as the conductive fluid. This other fluid is driven by the conductive fluid upon interaction therewith in the flow exchange 3 device 11 so that a difference in pressure exists between the inlet fluid and the outlet fluid.

In Figure 2, a more detailed view of a flow exchange device constructed in accordance with the present invention is shown. This device may be an integral unit comprising a plurality of

concentric cylinders

17, 19 and 21. These cylinders may be made of glass. However, any suitable material which does not interact chemically with the fluids to be handled may be used. The inner cylinder 17 has a bulbous portion 18 near the bottom. It is connected through a port 9 at the lower end thereof to a sorce of the primary driving fluid, which may be mercury that is pumped by an electromagnetic pump. The outer cylinder 19 is terminated near its lower extremes on the walls of the inner cylinder 17. Near the lower end of the outer cylinder, a port 20 is provided. The upper end of the outer cylinder 19 is terminated at the walls of the intermediate cylinder 21. The intermediate cylinder 21 extends upwardly, as viewed in the drawing, from a point over the bulbous portion 18 of the inner cylinder 17 to above the termination of the outer cylinder 19. A port 22 is connected to the intermediate cylinder 21 near the top thereof. Another port 24 is connected near the upper termination of the outer cylinder 19. The intermediate cylinder 21 is not terminated at the inner cylinder 17. However, the inner cylinder 17 and the intermediate cylinder 21 are disposed in cooperative relationship to define an elongated annular chamber 23 therebetween,

A cap 25 is provided to seal the upper end of the inner cylinder 17. This cap is conical in shape and may be made 5011i: of plastic, rubber or some other similar sealing material. An apertured cylinder 27 is inserted between the cap 21 and the walls of the inner cylinder 17. This apertured cylinder 27 may be provided, as illustrativcly shown, with three horizontally disposed rows of apertures. The apertures communicate with the annular chamber 23 formed between the inner cylinder 17 and the intermediate cylinder 21.

A rod 28 is attached to the top of the conical cap 25. This rod is yieldably secured to a stopper 29 which closes the top of the intermediate cylinder 21. A spring 30 is supported on a shoulder 31 which is fixed to the rod 28. Such yieldable support means for the cap 25, as the spring 30, is desirable in order to prevent damage to the

cylinders

17, 19 and 21 in the event that they are constructed from glass. Should a less brittle material be used, such yieldable support means may be eliminated, and the cap 25 and the apertured structure 27 may be made as an integral part of the inner cylinder 17.

During the operation of the flow exchange device, the primary driving fluid is pumped, by an electromagnetic pump for example, upwardly into the inner cylinder 17 through the port 9. This fluid passes through the apertured cylinder 27 and flows, in the form of finely divided droplets, through the annular gap 23 provided between the

cylinders

17 and 21. The driven fluid, which may be water, enters the intermediate cylinder 21 through the upper port 24 therein. This fluid fills the annular chamber 23 and flows upwardly through the chamber formed between the intermediate cylinder 21 and the outer cylinder 19 to the port 22 located near the top of the outer cylinder 19. The droplets of primary drive fluid flow downwardly through the driven fluid and drag the driven fluid along. This interaction between the droplets and the driven fluid gives a downward motion of flow to the driven fluid. This motion results in a hydraulic pressure upon the driven fluid.

The droplets flow around the bulbous portion 18 of the inner cylinder 17. The driven fluid and the primary drive fluid, which may be water and mercury, respectively, separate because of their difference in specific gravity. The primary drive fluid flows out of the port 20 at the bottom of the outer cylinder 19 and may be recirculated by means of an electromagnetic pump which is provided in accordance with the present invention.

An electromagnetc pump suitable for use in connection with the flow exchange device described above is shown in Figures 3 and 4. The pump structure is supported on a base 40. This structure comprises a loop of conductive fluid which is defined by an oblong closed tube 41. Inlet and

outlet ports

42 and 43, respectively, are connected at opposite ends of the tube 41. The tube 41 may be made from some insulating material such as glass. However, successful operation or the electromagnetic pump may be obtained if some other material is used, as long as the conductivity of the tube material is significantly less than the conductivity of the conductive fluid to be confined therein. The section of the tube near the outlet port 43 may be flattened as indicated on the drawing.

The poles 44 and 45 formed by an alternating current magnetic yoke structure 46 are placed on opposite sides of this flattened section. The yoke magnetic structure is made of magnetic material such as laminated iron. A magnetic circuit is completed through two legs 58 and 59 of the yoke 46 that are disposed outside of the oblong tube 41. A split central leg of the yoke 46 forms the poles 44 and 45. An alternating magnetic field is provided in a gap between the adjacent faces of the poles 44 and 45. This field passes through the flattened section of the oblong loop 41 and is perpendicular thereto.

A coil 47 is wound around the central leg of the yoke 46 which forms the upper pole 44 to provide a Winding thereabout. Another coil 48 is wound around the section of the central winding leg forming the other pole 45 to provide a winding thereabout. When energized by an alternating current, these coils provide the aforementioned alternating magnetic field between the faces of the poles 44 and 45.

As previously mentioned, it is desirable to eliminate the need for conductive contact with the fluid in an electromagnetic pump. To achieve this objective, an electric current is induced into the conductive fluid in the oblong loop defined by the tube 41 by means of electromagnetic induction. To this end, a magnetic core 49 is provided. This core is of the closed E type, and may be constructed from laminted iron. The central winding leg 50 of the core 49 is disposed inside of the oblong loop defined by the tube 41. The outside legs 51 and 52 are located outside of the loop defined by the tube 41. Therefore, the core 49 encloses and threads the oblong tube 41. A first coil 53 is wound around the central winding leg 50 and is disposed above the oblong loop 41. Another coil 54 is wound around the central winding leg 50 and is disposed below the oblong loop defined by the tube 41. It will be observed that these coils 53 and 54 will be magnetically linked with the oblong loop 41 and provide for the induction of an alternating current into the conductive fluid therein.

The interconnection of the coils and the circuit diagram of the electromagnetic pump described in Figures 3 and 4 is shown in Figure 5. The coils 53 and 54 which are disposed on the core 49 are connected in series. The outer end of one of these coils 53 is connected to a terminal 55 and the outer end of the coil 54 is connected through a capacitor 56 to another terminal 57. The terminals 55 and 57 are available for connection to a source of alternating current (not shown). These terminals 55 and 57 are also connected to opposite ends of the serially connected coils 47 and 48, which are disposed upon the yoke 46, and provide the magnetic field across the loop defined by the tube 41.

When an alternating voltage is applied across the terminals 55 and 57, the coils 53 and 54 are energized. An alternating current is induced into the conductive fluid in the loop defined by the tube 41 by electromagnetic induction. The fluid in the loop defined by the tube 41 forms a short circuit secondary as in a transformer. Therefore, a current of large magnitude is induced into the conductive fluid in the loop. This current circulates around the loop and flows in a direction perpendicular to the direction of the alternating magnetic field which is provided by the coils 47 and 48 in the yoke structure 46. The magnetic field produced by the current in the fluid conductor interacts with the alternating magnetic field provided between the poles 44 and 45, in well known manner, to produce a motor action which propels the conductive fluid through the port 43.

The proper phase relationship must exist between the alternating current and the alternating magnetic field provided in the yoke 46 in order to develop a force to propel the conductive fluid through the outlet port 43. The alternating current should attain substantially maximum amplitude at the same time as the alternating magnetic field attains maximum amplitude. Therefore, the alternating current must be substantially either in phase or 180 out of phase with the alternating magnetic field, depending upon reference direction selected for zero phase difference. The alternating current in the conductive fluid and the alternating magnetic field are both produced by electromagnetic action. Due to differences in the magnetic circuit leakage and due to different load resistivities, an out of phase condition occurs which may easily be corrected. A capacitor, such as the capacitor 56, may be connected in series with the coils 53 and 54. The value of this capacitor 56 is selected to shift the phase of the induced current and provide exactly the proper in phase relationship between the alternating current in the loop 41 and the transverse alternating magnetic field in the propulsion region.

When utilized in a pumping system such as shown in Figure 1, the inlet port 42 may be connected to the pipe 13 and the outlet port 43 may be connected to the other pipe 12.

What is claimed is:

1. An electromagnetic pump comprising means for directing a conductive fluid in a closed loop, inlet and outlet ports communicating with said loop, a winding magnetically linked with said loop, means coupled to said winding for applying alternating current to said winding for inducing an alternating current around said loop into said fluid in said loop, and means disposed adjacent to said loop near said outlet port for providing an alternating magnetic field transversely to said loop near said outlet port for propelling said fluid through said outlet port.

2. An electromagnetic pump comprising a closed loop conduit having inlet and outlet ports connected thereto, a conductive fluid contained in said conduit, a winding magnetically linked with said conduit, means coupled to said winding for applying alternating current to said winding to induce alternating current around said loop into said conductive fluid, a yoke structure constructed of magnetic material and including a pair of poles forming parallel, spaced pole faces having a gap therebetween, said pole faces being disposed parallel to said loop conduit and adjacent to said outlet port, and means for establishing an alternating magnetic field in said yoke structure between said pole faces which is in phase with said alternating current in said conductive liquid.

3. An electromagnetic pump comprising a conductive fluid, means providing a passage in the form of an oblong, closed loop for containing said conductive fluid, inlet and outlet ports connected to said loop to provide for the passage of said fluid through said loop, a magnetic core structure having a centrally located winding leg, said loop being disposed around said winding leg whereby said leg threads said loop, a coil wound around said winding leg, means electrically coupled to said coil for applying alternating voltages across said coil whereby an alternating current is induced around said loop into said fluid in said loop, and means disposed adjacent said outlet port for providing a magnetic field perpendicular to and intersecting said loop, said field being located adjacent to said outlet port so that said fluid is propelled through said outlet port.

4. An electromagnetic pump comprising means for confining a conductive fluid in a closed loop, said loop having a pair of ports for entry and exit of said fluid, means magnetically coupled to said loop for generating an alternating magnetic field and inducing an alternating current around said loop into said fluid in said loop, and means operatively associated with said loop near said exit port for generating another alternating field which is near said exit port and oriented transversely to said loop, said other alternating magnetic field being in phase with said current around said loop whereby said fluid entering said entry port is propelled out of said exit port.

5. An electromagnetic pump for a conductive fluid which comprises means establishing a closed loop path for said fluid, said means having an entrance and an exit, means propelling said fluid along said first named means in said loop path from said entrance to said exit including means inducing an alternating current around said loop path in said fluid in said loop path, and means operatively associated with said first named means and disposed transversely to said loop path and generating an alternating magnetic field which interacts with said current.

6. An electromagnetic pump for a conductive fluid which comprises means establishing a closed loop path for said fluid, said means having an entrance and an exit, and means propelling said fluid along said means in said loop path from said entrance to said exit including means inducing an alternating current around said loop in said fluid in said loop whereby to set up a first alternating magnetic field about said loop, and means operatively associated with said first named means and generating a second alternating magnetic field which intersects said loop path adjacent said exit and interacts with said first magnetic field.

References Cited in the file of this patent UNITED STATES PATENTS 1,298,664 Chubb Apr. 1, 1919 1,698,619 Blow Ian. 8, 1929 1,736,643 Beck Nov. 19, 1929 1,792,449 Spencer Feb. 10, 1931 2,159,179 Ringgenberg May 23, 1939 2,263,864 Avigdor Nov. 25, 1941 2,397,785 Friedlander Apr. 2, 1946 2,612,109 Wakefield Sept. 30, 1952 2,652,778 Crever Sept. 22, 1953 2,658,452 Donelian Nov. 10, 1953 2,787,219 Werner Apr. 2, 1957 FOREIGN PATENTS 698,623 Great Britain Oct. 21, 1953