US2930012A - Inductive apparatus - Google Patents

Description

March 22, 1960 A. HUFNAGEL mvucnvz APPARATUS 2 Sheets-Sheet 1 Filed Jan. 20, 1958 I I I I II IIIIIIIIIII I Hl H.

I0 llllll March 22, 1960 A. HUFNAGEL INDUCTIVE APPARATUS 2 Sheets-Sheet 2 Filed Jan. 20, 1958 INVENTOR. flzzcflw Han/220 05.

HIS ATTORNEY tors utilize opposing pairs of United States Patent 0,

2,930,012 INDUCTIVE APPARATUS Andrew Hufnagel, Penn Township, Pa., assignor to Westinghouse Wilmerding, Pa., a corporation Allegheny County, Air BrakeCompany,

of Pennsylvania My invention relates to inductive apparatus, and par ticularlyto an; improved construction for reactors, transformers, and thelike having cores madeof highly efficient grain oriented magnetic steels.

Iron core reactors are widely used in decoding units for'coded train control and coded wayside signal applications. Generally, in such a decoding unit, a reactor, is connected, in series; with a fixed condenser, andthe resultanttuned circuit is adjustedto the desired frequency by varying an air gap in the magnetic structure of the reactor.

Two forms of adjustabletcore reactors which have heretofore been widely used :are :shown and described'in Letters :Patent'of the United StatesNo. 1,869,364, granted August 2, 1932 to Leslie R. Allison, for Reactors, and .No. 2,446,624, granted August 10, 1948 to Leslie R. Allison, for Reactance Devices, both assigned to thesame assignee as the present application. Both of these reacflat .E-shaped laminations mounted with their legs confronting each otherso asto formair gaps .between them. Thelaminations are made of the usual type of transformer steel.

Since these reactors were developed, newer magnetic materialshave become available havinglower magnetic losses than heretofore obtainable, when the flux is in a particular direction therein. border to cause the flux to traverse these materials in the proper direction, the materials are rolled into strips which are wound into a multi-layer, closed magnetic loop usually held together byabanding strap. A core formed in this manner'does not readily lend itself to the having an adjustable air gap for circuit tuning purposes, and one object of my invention is to provide an economical reactor design which will enable these'ncwer magnetic materials to be used in tunedcircuits.

Another object of my invention is to provide a reactor having a winding linking a wound layer type of core, includingone or more air gaps, and in which the entire structure is'secured together by straps heldin place by a single clamping bolt.

Another object of my invention is to provide inductive apparatus of the type described that is compact and rugged, and which employs simple and easily manufactured parts.

. A; further object of my invention is to provide a' novel 'formof reactor, including means for varying the inductance of the reactor at the. time of assembly, and which may be readily returned in thejfiel'd to .meet a particular circuit requirement.

Other objects, purposes, and characteristic features of my invention will be in part obvious from the accompanying drawings and in part pointed out as the description proceeds.

In practicing my invention in accordance with one embodiment thereof, i provide a pair of magnetic cores each formedby winding asingle, flatsteel strip inamulti-layers to :form a closed magnetic loop. Each core isathen .separated to form upper and lower U shaped members havmanufacture ofa reactor 2,930,012 Patented Mar. 22, 1960 ing confronting legs with confronting faces normal to the axes of the legs. The lower U shaped members are placed in juxtaposition on a base plate, the axes of the confronting legs of the members being normal to the plate. Fixed and adjustable shims are placed on the faces of, the inside and outside confronting legs, respectively. A preformed coil is disposed about the inside legs of the lower members, and the upper U shaped members are then positioned so that their legs confront the legs of the lower U shaped members with the shims interposed therebetween. The cores, coil plate and shimsare rigidly secured in an assembled position by enclosing straps, securing blocks and a spacer bushing, all of which are apertured to receive a common bolt which isthreadably engaged by one of the blocks.

In tuning a reactor so constructed, the bolt is loosened to permit longitudinal movement of the adjustable shims until the desired level of inductance of the reactor is obtained. The bolt is then tightened to firmly securethe parts in their adjusted positions.

It is to be understood that my invention is not to be restricted to a reactor, but is applicable, in its broader aspects, to transformers and inductive apparatus requiring a core of the class described for its operation.

I shall describe one embodiment of my invention, and shall then point out the novel features thereof in claims.

In describing my invention, reference will be made to the accompanying drawings, in which corresponding parts are identified by corresponding reference characters and in which:

Fig. 1 is a front elevational view of a'reactor assembly embodying my invention.

Fig. 2 is a top plan view of the in Fig.1.

Fig. 3 is an enlarged perspective view of the retaining assembly of the reactor shown in Figs. 1 and 2.

Fig. 4 is an enlarged perspective view of a bimetallic shim employed in the reactor.

Referring to Figs. 1 and 2, a reactor assembly 1 is shown comprising a coil 2 of conventional construction mounted inv winding spaces 3 and 4 formed by two core loops 5 and 6 placed side by side.

The core loops 5 and 6 are each Wound of continuous strips of grain oriented magnetic steel providing high electrical efficiency so long as the flux traversesthe material in a lengthwise direction, and are then separatedinto upper U shaped members 7 and lower U shaped members 8 having the legs 7a and 7b and 8a and 8b, respectively, with confronting faces normal to the axes of the legs 7a and 7b and 8a and 8b. The confronting faces of legs 7a, 7b, 8a and 8b are ground smooth to keep magnetic reluctance to a minimum.

A base plate 9 supports the lower U shaped members 8. The base plate 9 has a central aperture 9a and is recessed at 9b on opposing sides parallel to the lengthwise direction of the strip stock forming core loops 5 and 6. Mounting holes 96 are formed in each corner of base plate 9 to facilitate securing the reactor assembly 1 to any desired support structure. The lower U shaped members 8 are placed in juxtaposition on base plate 9 in such a manner that the inside legs 8a are adjacent, and the axes of legs 8a and 8b are normal to plate 9 (Fig. 1).

Fixed shims 10 and adjustable shims 11 are placed on the faces of legs 8a and 8b. The fixed shims 10 may be of either magnetic or nonmagnetic material, depending upon the general level of inductance required in the reactor. The adjustable shims 11 are bimetallic and comprise a portion of suitable magnetic material, such as silicon steel, and a portion of nonmagnetic material, such as Phosphor bronze, joined-inend-toendrelation by any convenient means, such as butt welding (see Fig.

reactor assembly shown 4); The shims 10 and 11 have the same thickness, so that when the reactor is assembled and members 7 and 8 are drawn tightly together, full surface contact will take place between the shims and confronting faces of legs 7b 8b and 7a-8a, respectively. a Apertures 3 and 4 formed by core loops 5 and 6 receive coil 2. After coil 2 is disposed about adjacent inside legs 8a of lowermembers 8, upper U shaped members 7 are positioned with respect to members 8, so that confronting faces of legs 7a and 8a and 7b and 8b confront fixed shims 10 and adjustable shims 11, respectively (Fig. l). Referringnow to Figs. 2 and 3, assembled core loops 5 'and6, coil 2, and plate 9 are secured together by a retaining assembly 12. The assembly 12 comprises straps 12a, encircling the periphery of each'of the core loops 5 and 6, blocks 12b and 12g, plates 120, a spacer bushing 12d and a bolt 12e. Each end of straps 12a is secured between a block 12b or 12g, 7 by; any convenient means, for example, by rivets (Fig. 3). The' straps 12a, blocks 12b and 12g,-plates 12c, and spacer bushing 12d are provided with aligned apertures to receive the bolt 12a. The aperture 12h in the block 12g is threaded to engage threads provided on bolt 12e, whereby all of the parts may be secured together by means of the bolt 12c. On both block 12g and bolt 12c a large number of threads with a small clearance tolerance are used so that a lock nut is not required to retain the bolt in its tightened position. Spacer bushing 12disprovided to maintain a rigidly braced assembly which tends to prevent core loops 5 and 6 from bowing at a top center position 13 defined by adjacent legs 7a of upper U shaped members 7 (see Figs. 1 and 3).

As best shown in Figs. 1 and 3, plates 12:: bear on core loops 5 and 6 at 7c, and blocks 12b and 12g bear on straps 12a at 14. The thickness of straps 12a added tothe height of block 12b or 12g equals the height of plates 12c. This arrangement permits block 12b or 12g and straps 12a to form a nearly right angle with core loops Sand 6, when firmly secured, so as to rigidly retain reactor assembly 1. The blocks 12b and 12g, in bearing on straps 12a, force straps 12a to bear against core loops 5 and 6, thereby maintaining the shape and position of the'core loops.

As shown in Figs. 1 and 2, one of straps 12a, having its ends secured between block 1% or 12g and plate 120, encircles the periphery of core loop 5 and secures core loop 5 to base 9 by engaging recess 9b and passing through aperture 9a. In a similar manner core loop 6 is secured to base 9. Spacer bushing 12a is then placed into position as shown in Figs. 1, 2 and 3, and bolt 12:: is inserted within the aligned apertures in straps 12a, block 12b, plates 12c, and spacer bushing 12d, and retaining assembly 12 is tightly secured through the threaded engagement of bolt 12c and block 12g.

With reactor assembly 1 and retaining assembly 12 constructed and arranged in the manner described, bolt 12e is initially not fully tightened, thereby permitting a 'longitudinal movement of bimetallic shims 11 (see Fig. 2). The positions of bimetallic shims 11, between legs 7b and 8b, are varied simultaneously in a longitudinal direction to obtain the desired tuning by varying the reluctance of core loops 5 and 6. The bimetallic shims 11 are varied simultaneously to prevent unbalanced magnetic fiuxes in the two core circuits. With the nonmagnetic portions of bimetallic shims 11 in core loops 5 and 6, the reluctance will be at a high value, equivalent to the reluctance of an air gap. From test data taken on an experimental model, it was found that as the magnetic portions of bimetallic shims 11 are moved into core loops 5 and 6 at 7b-8b, the inductance of reactor assembly -1 increases in a fairly linear fashion. The linearrelation continues until. there is so much of the and a plate 12c 7 magnetic portions of bimetallic shims 11 within core loops 5 and 6 that the magnetic portions of the shims are no longer saturated. A further insertion of the shims will increase the inductance to a progressively lesser extent, because the cross-sectional areas of the inserted ,magnetic portions are now approaching the cross-sectional areas of the core loops. For this reason, the mag netic portion of bimetallic shims 11 need not be as long as the nonmagnetic portion. The positions of bimetallic shims 11 are varied within core loops 5 and 6 until the circuit is found to be in tune and reactor assembly 1 is then locked securely in place through threaded engagement between bolt 12c and block 12g.

Should it be necessary to retune reactor assembly 1 in the field, it is a relatively easy matter to loosen bolt 12e, reposition bimetallic shims 11 to a new level of inductance by the method previously described, and then retighten bolt 12c so reactor assembly 1 is rigidly secured.

Although I have herein shown and described only one form of .a -reactor embodying my invention, it is to be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A reactor, comprising, in combination, a base plate having a centrally located opening, a pair of multi-layer wound magnetic cores each having first and second generally U shaped members in a confronting relation with confronting legs and confronting faces, each of said first U shaped members being disposed on said base plate and having adjacent inside legs and spaced apart outside legs normal to said base, a coil disposed about said inside legs and confined by said first and second U shaped members in said confronting relation, adjustable shims disposed between confronting faces of said outside legs and fixed shims disposed between confronting faces of said inside legs, first and second straps each having first and second ends, first and second blocks and plates, said first endsof said straps being secured between said first blocks and plates, each of said straps passing along the outside edge of one of said cores, then under said base plate, through said opening and along the inside edge of the said one of said cores, said second ends being secured between said second blocks and plates to secure said cores to said base plate, a spacer bushing disposed between adjacent second ends of said straps to position said cores on said base plate, a bolt received within aligned apertures in said straps, blocks, plates and spacer bushing, and one of said first blocks threadably engaging said bolt, whereby said reactor may be rigidly held together or loosened to permit adjustment of said adjustable shims to vary the inductance in said reactor.

2. In a reactor, grain oriented magnetic strip material having maximum flux carrying properties in the direction of the grain orientation of said material and wound in multi-layers to form a pair of cores, each of said cores comprising first and second U shaped members in a confronting relation having confronting legs with confronting faces, a mounting plate having a centrally located opening, said plate engaging a closed end of said first U shaped members which form a pair of adjacent inside legs and a pair of spaced apart outside legs normal to said plate, a coil disposed about said inside legs and confined by said first and second U shaped members in said confronting relation, fixed shims disposed between 'confronting faces of said inside legs, and adjustable shims disposed between confronting faces of said outside-legs, a retaining strap running along the outside edge ofeach of said cores, passing under said plate, through said opening, and running along the inside edge of each of said cores, and having ends terminating adjacent the closed ends of said second U shaped members, and adjustable means for securing said ends, whereby said'reactor can be rigidly held together or loosened to permit adjustment of said adjustable shims to vary the inductance of said reactor.

3. In an inductor, a pair of substantially rectangular cores each comprising two generally U shaped pieces having abutting joints between the respective ends of the two pieces, said cores being arranged relative to each other to form substantially parallel outer legs and a pair of adjoining inner legs, at least one shim disposed between respective abutting joints of the inner and the outer legs of said cores, a coil disposed about said inner legs of said cores, a support plate for said cores and a hole in said plate, means for securing each of said cores to said plate running along the outer edge of each of said cores and under said plate, through said hole in said plate, and along the inner edge of each of said cores, the ends of each of said securing means terminating adjacent each other and having secured thereon enlarged portions for reinforcing said ends, means for spacing the inner ones of said ends of said securing means a predetermined distance apart, said spacing means, said ends of said securing means, and said enlarged portions each being provided with an aperture, and a single bolt for moving the ends of each of said securing means toward each other passing through said apertures and becoming threadably engaged to the last one of said enlarged portions through which said bolt passes.

4. Inductive apparatus of the class described comprising a pair of substantially rectangular cores each comprising two generally U shaped core members having abutting joints, said pairs being arranged relative to each other forming two spaced apart outside legs and two inside legs in juxtaposition, at least one shim disposed between respective abutting joints of the inside legs and the outside legs of said pairs of core members, a coil mounted on said inside legs, a mounting plate engaging adjacent bight portions of two of said core members and a hole in said plate, straps for binding each of said cores to said plate, each of said straps being adapted to extend along the outer edge of the outside legs of each of said cores and under said plate, through the hole in said plate, and along the inner edge of the inside legs of each of said cores, the ends of each of said straps terminating adjacent each other and having secured thereon means for reinforcing said ends, means for spacing the innermost ends of each of said straps a predetermined distance apart, said spacing means, the ends of said straps, and said reinforcing means each being provided with a hole, and fastening means passing through said holes and being adapted to adjustably engage the last one of said reinforcing means through which said fastening means passes, whereby by loosening said fastening means, adjusting the positions of said shims at said outside legs, and retightening said fastening means the reluctance of said core can be varied to provide any desired value of inductance in said core.

5. Inductive apparatus, comprising, in combination, four generally U shaped magnetic core members, each of said members having its legs confronting the legs of one other of said core members to form first and second pairs of core members, said first and second pairs of core members being disposed in parallel planes with one side of each of said pairs forming adjacent inside legs, a coil mounted on said inside legs, a mounting plate for said pairs of core members disposed normal to the axes of the legs of said core members, a pair of straps each being adapted to substantially encircle one pair of said core members and being further adapted to engage said plate to thereby rigidly hold that pair of core members against said plate when the ends of the strap associated therewith are drawn together, first means mounted to the ends of said straps for reinforcing said ends, means for spacing the inner ends of said straps a predetermined distance apart, said spacing means, said first means, and said strap ends each having a hole, and means for drawing the ends of each of said straps toward each other being adapted to pass through said holes and being further adapted to threadably engage the last one of said first means through which said last named means passes.

6. In a reactor, a substantially rectangular magnetic core comprising a pair of generally U shaped core members having confronting legs forming abutting joints, a mounting plate for said core members disposed in juxtaposition with the bight portion of one of said core members, at least one shim disposed between the abutting joints of said legs, a coil mounted on confronting legs of said core members in such manner that the shim between the abutting joints of the other of the confronting legs is accessible for adjustment, a strap being adapted to substantially encircle said core and being further adapted to engage said plate so that the force holding said shims in place is progressively increased as the strap ends are drawn toward each other, a hole in each of said strap ends, and means for moving the strap ends toward each other, thereby tightening said strap about said core, said last named means being in the form of a single bolt adapted to pass through said holes and being further adapted to threadably engage said strap ends so that when said bolt is loosened the shim may be positioned to change the reluctance of said core and thereby change the inductance of said coil.

References Cited in the tile of this patent UNITED STATES PATENTS 2,165,055 Kaflca July 4, 1939 2,459,374 Goodrich Ian. 18, 1949 2,655,717 Dunn Oct. 20, 1953 2,835,876 Hammond May 20, 1958

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