US2966858A

US2966858A - Electromagnetic fluid pump

Info

Publication number: US2966858A
Application number: US487354A
Authority: US
Inventors: John F Peters
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1955-02-10
Filing date: 1955-02-10
Publication date: 1961-01-03
Anticipated expiration: 1978-01-03

Description

Jan. 3, 1961 J. F. PETERS 2,966,858 ELECTROMAGNETIC FLUID PUMP Filed Feb. 10, 1955 3 Sheets-Shet 1 John F. Peters MIM ATTORNEY lJan. 3, 1961 J. F. PETERS 2,966,858

ELECTROMAGNETIC FLUID PUMP Filed Feb. 10, 1955 3 Sheets-Sheet 2 mvENToR John F. Peters Jan. 3, 1961 J. F. PETERS 2,966,858

ELECTROMAGNETIC FLUID PUMP Filed Feb. l0, 1955 3 Sheets-Sheet 5 John F. Pe'rers 2,966,858 ELECTROMAGNETIC FLUID PUMP John F. Peters, Edgewood, Pa.,

Electric Corporation, tlon of Pennsylvania Filed Feb. 1t), 1955, Ser. No. 487,354

Claims. (Cl. 103-1) assigner to Westinghouse East Pittsburgh, Pa., a corpora- My invention relates to pumps generally, and more particularly to electromagnetic pumps for electrically conducting iiuids.

Electromagnetic pumps of the type where a conducting fiuid is impelled along a conduit by the reaction of a transverse current through the fiuid perpendicular to both the fiow of the tiuid and an impressed magnetic field have been used in the past for handling electrically conducting uids due to the mechanical simplicity of such pumps.

While these pumps are desirable because of their mechanical simplicity, prior pumps have had a low electrical efiiciency. I have discovered that the electrical efiiciency of electromagnetic pumps can be increased by providing an impressed magnetic field of varying strength so that the magnetic iiux through the air gap between the pole pieces, due to the impressed magnetic field, is greater at the outlet of the pump chamber than at the inlet. The combination of any impressed magnetic field of varying strength and the magnetic field which surrounds the transversecurrent provides a magnetic field of uniform strength between the inlet and outlet of the pump chamber which increases the efficiency of the unit. The transverse electrical current through the fiuid of an electromagnetic pump is of considerable magnitude and the magnetic field surrounding this current seriously distorts the impressed magnetic field` in the previous designs.

I have further improved the efficiency of this type of pump by a particular arrangement of the incoming and outgoing conductors which supply the transverse current, so that the current iiow is divided at opposite sides of the pump unit. An electromagnetic pump requires a transverse current of considerable magnitude; thus, the magnetic field surrounding these conductors is large and may seriously impair the performance of the impressed magnetic field. I have prevented this reduction in the performance of the impressed magnetic field by dividing the conductors to allow half of the current to fiow on each side of the magnetic structure. Thus, the magnetic field surrounding the conductor on one side will be effectively cancelled at positions adjacent the magnetic structure by the magnetic field surrounding the other half of the same conductor on the opposite side of the pump.

Accordingly, the principal object of my invention is to provide an electromagnetic pump with increased eiiiciency due to a novel arrangement of the magnetic structure and of the bus bars conducting current to the pump unit.

Another object of my invention is to provide a novel electromagnetic pump wherein the field produced by the magnetic structure is correlated with the field produced by the current supply conductors to produce a uniform tiled acting on the being pumped.

Another object of my invention is to provide an elec* tromagnetic pump with a magnetic structure of varying strength.

Another'object of my invention is to provide a electromagnetic pump with a unique arrangement for the members that conduct electrical current to the pump unit.

`These and other objects and advantages will be apparent atent ICC from the following description of a preferred embodiment of my invention, when taken in conjunction with the accompanying drawings, in which:

Figure 1 is a front View of an electromagnetic pump constructed according to my invention showing a partial section view of one of the bus bar connections, and a partial section view of a central portion of the pump unit showing the inclined pole faces;

Fig. 2 is a right end view of the electromagnetic pump shown in Fig. 1 with the pump chamber portion being shown in section; and

Fig. 3 is a top View of the electromagnetic pump shown in Fig. l.

Referring now to the illustrative embodiment of the invention, and particularly to Figs. 1 and 2, there is shown an electromagnetic tiuid pump constructed according to my invention, the magnetic structure of which is comprised of a rectangular frame 2, preferably of a magnetic material, such as electrical steel, having vertical side members 4 and connecting top and bottom members 6. The top and bottom members may be attached to the side frame members 2 by any suitable means, such as welding or bolting. Tapered legs 8 are attached to the bottom member 6 by any suitable means, such as bolting (not shown), so that the vertical axis of the unit is inclined slightly in a plane perpendicular to the direction of flow of the fluid. This inclination of the vertical axis is desirable in order for the fluid in the unit to drain back to a central reservoir when the unit is shut down or when it is desired to service the unit (instead of freezing in the pump chamber and thus damaging it). Two permanent magnets 1t) and 12, preferably of a good magnetic material, such as soft iron, having converging sides 11 and 13, respectively, are attached at their outer ends to mounting

plates

14 and 16, respectively, by any suitable means, such as cap screws 18.

Mounting plates

14 and 16 are secured to the top and bottom members 6 of the rectangular frame by means of cap screws 18. The sides 11 and 13 of the

magnets

10 and 12 converge towards each other, and the inner ends of the magnets terminate in spaced relation. Attached to the spaced inner ends of

magnets

10 and 12, by any suitable means, such as bolts (not shown), are pole pieces Ztl and 22, respectively, preferably of an easily magnetized material, such as soft iron, and having opposed inclined convergent faces 19 and 21, respectively. I incline the faces 19 and 21 of the

pole pieces

20 and 22, so that the air gap between them, and thus the strength of the magnetic field between the opposed pole pieces is greater at one end of the pump than the other. I vary the strength of the magnetic field between the

pole pieces

20 and 22, so that when it is combined with the magnetic field which surrounds the transverse current fiowing through the fiuid being pumped, an

. impressed magnetic field of uniform strength will result.

The conduit 26 for the fluid being pumped is adapted to be coupled to the remainder of the system piping by means of enlarged end sections 241 which have a circular cross-section. The end sections 24 are joined, as by welding or the like, to the pump conduit 26 by means of converging transition pieces Z8. The pump conduit 26 is preferably of rectangular cross-section and of reduced area and is also preferably of an electrically conducting non-magnetic material, such as stainless steel. Pump conduit 26 is centrally positioned between the adjacent faces of

pole pieces

20 and 22 and supported by means of wedge-shaped members 23 and bus bars 40, which will be described later. Wedge-shaped members 23 are preferably of a non-magnetic material, such as stainless steel, and are designed to fill the wedgeshaped spaces between the pump conduit 26 and the inclined faces 19 and 21 of

pole pieces

20 and 22, respectively, and are retained in position by means of the bent-over tabs 31 on clamps 32. Clamps 32 are secured to the sides of

pole pieces

26 and 22, respectively, on the sides thereof at the left, as viewed in Fig. l at the inner end of each pole piece, by means or cap screws 33. A sheet of insulating material 27, preferably a high-temperature resistant electrical insulating material, such as mica, is interposed between the conduit 26 and the wedges 23 in order to insulate the magnetic structure from the pump conduit 26. I have thus provided by the above structure for the physical retention of the conduit 26 between the pole pieces 2t) and 22 with respect to vertical movement, and have avoided any mechanical connections between the conduit 26 and the respective pole pieces; therefore, the pump conduit 26 is free to expand or contract longitudinally independent of the pole pieces as the temperature of the fluid being pumped changes,

In order to prevent excessive loss of the transverse current, due to short-circuiting through pump conduit 26, at its ends, the wall thickness of the ends of pump conduit 26 must be maintained at least of no greater thickness than the center section, so that no less resistance to the flow of the transverse current will exist at Athe ends than exists in the central portion of pump conduit 26. This means that the walls of conduit 26 must be quite thin, and preferably i maintain the walls of pump conduit 26 of the same thickness throughout its length. In order that such a thin-walled conduit be better able to withstand the pressure of the iiuid being pumped, l have provided a reinforcing structure for the ends of pump conduit 26. My reinforcing structure consists of -a plurality of spaced washers Sti having a rectangular center hole, so that they may receive the pump conduit 26. Straps 36 are attached to each washer 39 at opposite sides by any suitable means, such as welding, to maintain each washer in its proper spaced position. The outer washer of each reinforcing structure is attached to pump conduit 26 by any suitable means, sucn as a small tack weld. It is necessary to attach one washer to pump conduit 26 in order to maintain the reinforcing structure in the proper longitudinal position.

By close spacing of the washers 30, I have reinforced the pump conduit 26 at corresponding spaced points and prevent its rupture due to pressure of the iluid being pumped, even though the conduit walls are maintained quite thin. In addition, I have avoided all mechanical connections between the washers 30 and the pump conduit 26, except a small tack weld on the outer washer, so that the resistance to the ow of the transverse current will remain the same at the end portion as in the central portion of pump conduit 26 and, in addition, allow the pump conduit 26 freedom to expand and contract longitudinally with changes in temperature. Thus, since the resistance to the flow of the transverse current is the same throughout the length of the pump conduit 26, such current will ow between the bus bars to be described later, by means of the shortest path which is through the central portion of the pump chamber and iluid in the pump chamber. It is not necessary to provide any reinforcing structure for the center section of pump conduit 26 in my design, because this section is physically restrained by the wedges 23 described above, and by the bus bars, to be described later.

U shaped bus bars or other suitably shaped conducting members 40, and atl preferably of a good electrical conducting material, such as copper, each have a bight portion 4l extending across the front and back of the pump, respectively, with upwardly extending arms 45 at each end, and an inwardly extending lateral projection 42 from the central portion of the bight portion 41. The projections 42 each have a reduced outer portion 43 which are attached to the side walls of conduit 26 at opposite sides thereof by any suitable means, such as brazing. Each bight portion 4i is supported at its upper and lower surfaces in the rectangular frame member by angle brackets 39 which are positioned on the top and bottom of each bight portion 4l and, although not mechanically attached to it, physically restrain its vertical movement. The brackets 39 are secured to side members `4- of the rectangular frame by any suitable means, such as bolts (not shown). A channel-shaped insulating sleeve 44, preferably of an electrical insulating material, such as mica, surrounds each bight portion 41 and insulates it from angle brackets 39.

The legs 45 of the front bus bar 40 are each connected to a pair of similar vertical conductors or bus bars 46 by means of studs 4S and nuts 50 and 5l. The studs 43 also serve to anchor the legs i5 to a cross brace 58 on the rectangular frame of the magnetic structure. Studs 48 are insulated from the legs 45, vertical bus bars 46, and cross braces 58 by means of an insulating sleeve 52, preferably or an electrical insulating material, such as mica. The nuts Sti are insulated from the bus bars 46 by means of washers, 5a, preferably an insulating material, such as mica, and the nuts 5l are insulated from the cross braces 5S by sheets 56 of similar material. An additional sheet 56 is used to insulate the bus bars 46 from the cross brace 58. Cross braces 58 are bolted to projections 62 on the side members 4 of the rectangular frame by means of bolts 60. The legs 45 of the other bus bar 40' are each connected to a pair of similar vertical conductors or bus bars 46 and supported from a brace 58 by a structure which is a duplicate of that used for the front bus bar. Vertical bus bars 46 diier from vertical bus bars 46 only in that they are shorter.

The structure described above for anchoring the legs 45 of the bus bars itl and 46 to the cross braces 56, also serves to physically restrain the pump conduit 26 from lateral movement. I have avoided mechanical connections between the bight portions 41 of bus bars 44D and 49 and the angle brackets 39, in order to allow a restricted lateral movement of the intermediate portions of the bus bars and pump conduit 26 to take care of expansion and contraction of the bus bars and conduit with changes of temperature of the fluid being pumped. The restricted lateral movement of the intermediate portions of the bus bars 40 and 40 is possible even though the ends of the bus bars are firmly anchored to the rectangular frame due to exing of the bus bars. This structure, in combination with the wedges 23 described above, maintains the pump conduit 26 accurately in position between the

pole pieces

26 and 22, yet allows sufficient freedom of movement to enable the pump conduit 26 and the intermediate portions of bus bars 4t? and 40 to expand and contract with changes in ternperature.

The upper magnet it) of the unit is insulated from the heat generated in the vertical bus bars 46 and 46 by means of

panels

64 and 66, preferably of an insulating material, such as asbestos faced with aluminum, which are secured to the top member 6 and cross braces 58 by means of

clips

63 and 65, respectively.

The vertical bus bars 46 and 46 are attached to

suitable power buses

63 and 70, respectively, on each side of the pump unit by any suitable means, such as bolting (not shown).

Power buses

68 and 7@ at each side are composed of a number, for example, six, bus bars 67, preferably of a good electrical conducting material, such as copper, each having the same cross-sectional area. The bus bars 67 may be grouped together in any suitable arrangement to form power buses 63 and 76, for example, two bus bars 67 may be grouped in a pair and three such pairs may comprise

power buses

63 or 7?, respectively, on each side, as shown in Figs. l and 3. The power buses 68 shown in Fig. 3 may converge beyond the pump and form one power bus comprised of six pairs of bus bars 67, and a similar arrangement may be provided for power bus bar 7G.

By means of the structure described above, a current may be introduced through power bus 70, for example,

and will fiow in equal quantity through the vertical bus bars 46 into each end 45 of the U shaped bus bar 40' at the back of the pump, since the total cross-section of power buses 70 and vertical bus bars 46 are the same on each side of the unit. The current flow will then proceed from the ends of this bus bar 40 toward the lateral extension 42 thereof and then through the pump conduit 26 into the front U shaped bus bar 40, as viewed in Fig. 1 of the drawings, where -it will divide and flow equally out each end 45 thereof into vertical bus bars 46, and then return to the source by me-ans of power buses 70. I have, thus, provided a structure whereby half of the current flowing into and half of the current flowing out of the pump unit will flow on each side of the units magnetic structure.

As described above, the pole piece 20, shown in Fig. 1, may be the north pole (N), and the pole piece 22 may be the south pole (S). If the current flowing in the upper power bus bar 68 is negative and the current owing in the lower power bus bar 70 is positive (-l-), then a force will act on the uid in conduit 26 causing flow of the fluid in the pump conduit 26 from left to right as viewed in Fig. 1, as shown by the arrow. The current flowing transversely through the pump conduit 26 has a magnetic field surrounding it in which the lines of flux will flow in a counter-clockwise direction, as viewed in Fig. 1, if the current flows as assumed above. Thus, the lines of flux surrounding the current flowing through the pump conduit will add to the lines of flux of the magnetic structure on the left or inlet side of conduit 26 and subtract on the right or outlet side. In previous designs, this effect would distort the impressed magnetic field and resulted in a low efficiency of the pump, but in my design, I vary the strength of the impressed magnetic field along conduit 26 from a minimum at the inlet to a maximum at the outlet, so that the resultant of the impressed magnetic field and the magnetic field surrounding the current flowing through the pump chamber results in a uniform field along the length of the pump conduit. I prefer to obtain an impressed magnetic field of varying strength by inclinng the faces 19 and 21 of the pole pieces 2) and 22 which increases the `air gap between the pole pieces on one side which results in a decrease in the strength of the field at this side, and decreases the air gap on the other side with a resultant increase in the strength of the field, as described above. The pumping force acting on the liquid being pumped is thus made to be uniform along the entire length of pump conduit 26, which results in a more efiicient pumping action.

I have split the vertical bus bars and power buses so that half of the current flows on each side of the magnetic structure to or from both ends of the bus bars 40 'and 40', respectively. Thus, for example, the magnetic field surrounding the power bus 68 and vertical bus bar 46 on one side of the structure is effectively cancelled at positions adjacent the magnetic structure by the magnetic field surrounding the power bus 68 and vertical bus bar 46 on the other side of the structure, since both magnetic fields are equal but have opposite directions where they flow through the magnetic structure of the unit. The same is true for the magnetic fields which surround the power buses 70 and vertical bars 46. n

In previous designs, the power buses were connected to the bus bars supplying the transverse current to the pump conduit on one side of the unit only, and thus the magnetic field surrounding these power buses would seriously distort the impressed magnetic field and produce a greater maximum flux density in the iron than in the case of a uinform fiux density. This magnetic field set up by the current in the bus bars also extends into the iron structure of the pump and interferes with and. distorts the magnetic field set up in the rectangular frame by the magnets and 12. The distorted magnetic eld pro duces a greater maximum flux density in the magnets and frame structure than would be obtained if the flux density were uniform. Since the maximum flux density is limited by the magnetic characteristics of the material in the magnets and frame, the distorted magnetic field will require a larger cross-sectional area in the magnets and frame than would be required by a uniform field without any increase in capacity or performance of the unit. In addition, when permanent magnets are used and the current in the bus bars is large, the magnetic field due to the current will have a serious demagnetizing effect on the permanent magnets.

While I have shown only one embodiment of my invention, it is susceptible to various modifications, for example, electromagnets may he substituted for the

permanent magnets

10 and 12. Also, the

power buses

68 and 70, which I have shown horizontal, could be vertical, or at any other angle, and the elimination of the distortion in the magnetic structure due to the current iiowing through these power buses, would still be accomplished in the same way.

I claim as my invention:

1. A dynamoelectric machine comprising a magnetic structure having a rectangular frame and permanent magnets mounted in said frame, said magnets having inclined pole pieces so that the magnetic flux produced by said magnets is greater at one end of said pole pieces than the other, a tubular pump chamber having diverging end sections and a straight center section of uniform wall thickness, said center section being positioned between said pole pieces, re-enforcing means for each end of said center section where it extends beyond said pole pieces, two U-shaped bus bars, one of said bus bars being attached by its bight portion to one side of the unre-enforced portion of the center section of said pump chamber, the other of said bus bars being attached by its bight portion to the opposite side of said pump chamber directly opposite said first bus bar, power conductors attached to each leg of both said U-shaped bus bars to cause a current flow through said center Section of the pump chamber.

2. An electromagnetic pump comprising, an open rectangular frame, a magnetic structure supported by said frame including opposed pole pieces mounted on opposed walls of said frame, respectively, and extending inwardly and terminating in spaced pole faces, a tubular pump conduit extending through said frame in the space between said pole faces in insulated relation thereto and being free for relative movement except in the plane through said pole pieces, means restricting movement of said conduit laterally of said pole pieces comprising electrical conductors electrically connected to opposite sides of said conduit, respectively, in the region of the space between said pole faces and extending longitudinally of said conduit, means on opposite sides of said frame for securing each end of each of said conductors to said frame at a point outwardly beyond said pole faces, and lmeans on said frame engaging said conductors adjacent said pole faces for restraining movement of the conductors in the aforesaid plane through the pole pieces but permitting movement thereof in a transverse plane.

3. A dynamoelectric machine comprising a magnetic structure having spaced opposed pole pieces, a tubular pump chamber positioned between said pole pieces and protruding outwardly thereof, bus bars attached to opposite sides of said pump chamber at positions adjacent said pole pieces, circuit means for coupling said bus bars to a source of electric potential, and pump chamber reinforcing means secured to the protruding portions of said pump chamber, said reinforcing means including a plurality of spaced loosely fitting washers surrounding said protruding portions, and means for securing said washers one to another and for securing at least one of said washers to said pump chamber, whereby the walls of said protruding portions substantially are confined against transverse expansion without substantially increasing the iiow of transverse current through the walls of said pump chamber.

4. A dynamoelectric machine comprising a magnetic structure having spaced opposed pole pieces, a tubular pump chamber positioned between said pole pieces, a pair of elongated bus bars, the intermediate portions of said bus bars being attached to opposite sides of said pump chamber at positions adjacent said pole pieces, a pair of conductive members secured to the ends, respectively, of each of said bus bars, circuit means coupled to each pair of said conductors for connecting said bus bars to a source of electric potential, each pair of said conductive members being substantially parallel and being spaced equidistantly from said magnetic structure to prevent mag netic distortion of said structure due to currents induced by said potential.

5. A dynamoelectric machine comprising a magnetic structure having spaced opposed pole pieces, a tubular pump chamber positioned between said pole pieces, a pair of elongated conducting members attached respectively to opposite sides of said pump chamber, and means secured to the ends of each conducting member for forming substantially similar current paths between each conducting member and a source of electrical potential, those portions of each of said means which are disposed respectively adjacent the inlet and outlet of said pump chamber being substantially similar, so that magnetic distortion of said structure due to currents induced by said potential is substantially prevented.

6. A dynamoelectric machine comprising a magnetic structure having spaced opposed pole pieces, a tubular pump chamber positioned between said pole pieces, said pole pieces being inclined so that the magnetic flux between said pole pieces is greater at the outlet of the pump chamber than at the inlet thereof, a wedge-shaped member fabricated from a non-magnetic material inserted between and engaging each of said pole pieces and the adjacent portion of said pump chamber, each of said wedge members supporting said adjacent portion, bus bars disposed at an angle to said pole pieces and having at least their intermediate sections attached respectively to opposite sides of said pump chamber whereby the walls of said pump chamber are coniined against transverse expansion by said wedge-shaped member and said bus bars, and circuit means for connecting said bus bars to a source of electric potential.

7. A dynamoelectric machine comprising a magnetic structure having spaced opposed pole pieces, a tubular pump chamber positioned between said pole pieces, said pole pieces being inclined so that the magnetic flux between said pole pieces is greater at the outlet of the pump chamber than at the inlet thereof, a wedge-shaped member fabricated from a non-magnetic material inserted between each of said pole pieces and the adjacent portion of said pump chamber, each of said wedge members supporting said adjacent portion, bus bars disposed at an angle to said pole pieces and having at least their intermediate sections attached respectively to opposite sides of said pump chamber, whereby the walls of said pump chamber adjacent the pole pieces are conned against transverse expansion by said wedge-shaped members and said bus bars, said pump chamber protruding outwardly of said pole pieces, additional pump chamber reinforcing means secured to the protruding portions of said pump chamber, said reinforcing means including a plurality of spaced loosely fitting washers surrounding said protruding portions, and means for securing said washers one to another and for securing at least one of said washers to said pump chamber, whereby the walls of said protruding portions substantially are conned against transverse expansion without substantially increasing the ow of transverse current through the walls of said pump chamber.

8. A dynamoelectric machine comprising a magnetic structure having spaced opposed pole pieces, a tubular pump chamber positioned between said pole pieces, said pole pieces being inclined so that the magnetic iluX between said pole pieces is greater at the outlet of the pump chamber than the inlet, a pair of elongated conducting members attached respectively to opposite sides of said pump chamber, and a pair of conductors attached to each of said conducting members for eiecting a current ow through said pump chamber, each pair of said conductors being attached respectively to opposite ends of the associated one of said conducting members at positions respectively adjacent the inlet and outlet of said pump chamber, one of said pairs of conductors being disposed respectively in a substantially symmetrical arrangement relative to the other of said pairs so that magnetic distortion thereadjacent is prevented.

9. A dynamoelectric machine comprising a magnetic structure having spaced opposed pole pieces, a pump chamber positioned between said pole pieces, said pole pieces being tapered so that the magnetic ux is greater at the outlet of the pump chamber than at the inlet, a pair of elongated conducting members attached at intermediate portions thereof to opposite sides respectively of said pump chamber, and a pair of conductors connected to each of said conducting members for supplying current thereto, and each pair of said conductors being attached respectively to opposite ends of the associated one of said conducting members at positions respectively adjacent the inlet and outlet of said pump chamber, the adjacent ones of said conductors being substantially symmetrically disposed to prevent distortion of the magnetic iield in said pump chamber by the field induced by the current owing in said conductors.

10. A dynamoelectric machine comprising a magnetic structure having spaced opposed pole pieces, a tubular pump chamber positioned between said pole pieces, a pair of elongated conducting members, the intermediate portions of said conducting members being attached to opposite sides of said pump chamber at positions adjacent said pole pieces, a pair of conductors attached to each of said conducting members for eiecting a current ow through said pump chamber, each pair of said conductors being attached respectively to opposite ends of the associated one of said conducting members at positions respectively adjacent the inlet and outlet of said pump chamber, the adjacent ones of said conductors being disposed substantially symmetrically relative to said magnetic structure.

References Cited in the tile of this patent published by U.S. Government Printing Oice (Washington, D.C.), 1950. Page 158 relied on.