US2579522A - Transformer construction - Google Patents

Description

Dec. 25, 1951 H. A. sTRlcKLAND, JR 2,579,522

TRANSFORMER CONSTRUCTION Filed Feb. 4, 1946 4 sheets-sheet 1 3 3 il w A* 3! l mi* 1'! 2 SERLLS I l ,ll Q 5 o o 62 9 6-- 4 O. 4 I :ai 4@ "L A i l' 5 in E f O O 6 Mini-V i@ l 63 I o o lj O O v I|| |l||||l semis. @i 45 4 H-ii @o 22 24 B O O O PARALLEL n ,245 'EF-'g8 O O O Erg/9 o O O O li O Q.. O [C O i@ 69 o "6 O G Q Q/' O O 'y Wp 2,5 O www Q O O O O O O O O O l G IZ l? E Q O. G 0 Q- o] 68 O q o O LQ O o m LL 2O Lr i o o Q 23 INVENTOR K PARALLEL ,u i {BY-Harold Q. gjcncklcmdr.

ATTORNEY Dec. 25, 1951 H. A. sTRlKLAND, JR 2,579,522

TRNSFORMER CONSTRUCTION Filed Feb. 4, 1946 4 Sheets-Sheet 2 i2 i I yllg'. 2.

'r mvENToR U Harold H Stttcklcmdi ATTOR N EY Dec. 25, 1951 H. A. sTRlcKLAND, JR 2,579,522

TRANSFORMER CONSTRUCTION 4 sheets-sheet :5

Filed Feb. 4, 1946 lllllllllilll -lNVENTOR `Hcufold UQ. Stricklandjr.

ATTOR N EY Dec. 25, 1951 Filed Feb. 4, 1946 H. A` sTRlcKLAND, JR

TRANSFORMER CONSTRUCTION 4 Sheets-Sheet 4 INVENTOR LHcufold TH. SJfrtckldndf BY Z L l ATTORNEY Patented Dec. 25, 1951 TRANSFORMER CONSTRUCTION Harold A. Strickland, Jr., Detroit, Mich., assignor, by mesne assignments, to The Ohio Crankshaft Company, Cleveland,A Ohio, a corporation of Ohio Application February 4, 1946, Serial No. 645,449

1 Claim. (Cl. 175-356) This application relates to transformers with particular application to transformers employed for induction heat treatment where a range of different output voltages is required.

Among the objects of the invention are to provide improved means for changing the connection to the secondary turns of the transformer to establish either series or parallel relationships; to provide transformer apparatus in which the secondary connections may be changed Without possibility kof misconnection to the electrical circuits; `to provide transformer structure which embodies pronounced simplicity in design and arrangement; to provide improved means for insulating the electrical turns of the coil from the core and other metallic parts of the unit; and to provide effective secondary winding cooling means.

The above and other objects of the invention bearing more closely on structural details are made effective in the embodiment of the invention hereinafter described and illustrated in the accompanying drawings, in which:

Figure 1 is a front elevation of the transformer with yokes connected to give series connections between the coils of the secondary;

Figure 2 is a side elevation of the transformer;

Figure 3 is a rear elevation of the transformer with a portion of the coils and overlying panel broken away to show the primary and secondary coils in section;

Figure 4 is a horizontal section taken on lines of Figures 1 and 2;

Figure .5 is a fragmentary horizontal section taken on lines 5 5 of Figures 1 and 2;

Figure 6 is a fragmentary horizontal section taken on lines 6 6 of Figures 1 and 2 but disclosing the parallel yoke connection;

Figure '7 is a vertical section taken on lines 'l-l of Figures 2 and 4;

Figure 8 is a detail showing the yoke connection to the secondary terminals as connected in parallel;

Figure 9 is a face view .of the terminal blocks ofthe secondary turns;

Figure 1Q is a fragmentary side elevation following the showing of Figure 2 but illustrating the yolies in parallel;

Figure ll is a perspective of the secondary coil and terminal blocks diagrammatically illustrating the parallel connection; and

Figure 12 is a perspective similar to Figure 11 but diagrammatically indicating the series connection.

Generally stated the structure involved in this 2 .c disclosure is a transformer adapted for use in iii-- ductive heat treatment of metal articles which is susceptible to electrical modification so as to change with comparative ease the energy absorption of the furnace. Heretofore taps have been employed on the primary of the transformer for making voltage adjustment of the output but there are limits to which modification of the turn ratio of the transformer can be employed usefully as limited to the primary Winding only. Where large current values are employed modification of the secondary winding as to number of turns has oifered difficulty and the structure now to be described seeks to provide a satisfactory method and arrangement which overcomes this difficulty.

Referring to Figures 1 and 2 the general set-up of the transformer is made apparent. A core I lis formed of a plurality of laminated plates 2 which are E-shaped and bound together in stacks by means of retaining bolts 3 and 4 at the base sections of the E plates and bolts 5 and 6 at the free end sections of the plates to form a shelltype core with an internal cylindrical opening within which, and about the solid inner core section,l the windings of the transformer are placed. In assemblage the coil is placed in the annular inner opening of the core section 1 and then the core section 8 is placed over the coil to bring the ends of the laminations of the two units in registry. The sections 'l and 8 are then bound together by means of steel tapes I3. Plates 8 and I0 are to locate winding relative to core and are retained by the insulated metal bolts 5 and 6. The core is supported from any suitable base by means of brackets Il and l2, the brackets Il being attached to the bottom bolts 4 and the brackets I2 to the top bolts 3. Strips i3 are placed around the edges of the core laminations to assist in holding the core and auxiliary apparatus such as cooling units in a compact unit.

The windings of the transformer are two in number and as illustrated particularly in Figures 3 and 4 consist of a primary Winding I4 enclosed by a secondary winding i5, The primary Winding consists of a number of turns of electrical conductor, preferably tubular and square in cross section. Twenty-three turns may be mentioned as an example of a satisfactory number for the apparatus as used. These turns are in a single layer around an insulating tube l 6 separating the central core section from the coil. The conductor is provided with an insulating tape winding so as to prevent short circuiting between turns. Surrounding the primary coil and spaced there- .from by a second layer of insulation I'l is the secondary winding I5. This winding consists of two turns, the upper turn being designated by the numeral I8 and the lower by the numeral I9. These turns are axially aligned and are spaced from each other and each consists of a U-shaped plate conductor of such cross sectional area as to permit ow of heavy currents required for the heating action.

As illustrated more clearly in the perspective drawings of Figures 11 and 12, I have provided novel means for facilitating series or parallel connections of the single turns of the secondary coil in a connector unit including two bus bars 29 and 2I. the bus bar 20 having direct conducting connection to one terminal of the secondary turn I8 and the bus bar 2| having a direct conducting connection to one single terminal of the secondary turn I9. The bus bars are also positioned together as a unit but insulated from each other. Each bus bar is also insulated from the other turn. The specific structural relationship of these bus bars to the secondary turns may be examined more closely in Figures 4 to to which attention is now directed. Referring to Figure 4 and the associated detail figures, it will be seen that the bus bars 20 and 2l Vare spaced from each other by a sheet of insulation 22 and that the bus bar 2| is insulated from the terminal 23 of the secondary turn I3 by means of an insulation strip 2 4. Also the bus bar 2li forms a continuous conducting path with the other terminal 25 of the secondary turn 18. Any appropriate mode of connection between the turn plate winding and the terminals may be used. The use of bolts is indicated in the gures as a satisfactory means. If reference be now made to Figure 9 it will appear that the bus bar 2| is continuous with the terminal 25 of the lower secondary turn I9 which is in alignment with the terminal 23 -of the upper turn and that the opposite terminal 21 of turn I9 is spaced from the bus bar 2li by means of insulation 28. Thus the diagonally oppositely positioned terrnnals 23 and 21 of the secondaryy turns are insulated from the adjacent bus bars while the other turn terminals 25 and 2S are integral or continuous with the adjacent bus bars. v

The primary winding I4 is provided with appropriate terminals and tapsV for making connection to the current sourcejthe upper and lower end terminals being indicated respectively by the numerals 39 and 3l and. the intermediate taps by the numerals 32, 33 and 34. In the case ci' the end terminals 39 and 3l the conductor is singular and connects with bus bar tubes 35 through an intermediate laterally adiustable coupling 36. Also in the case of the taps 32, 33 and `34 which are formed of two end units of the primary coil, connection is made by appropriate couplings 36 to the bus bar tubing 31. 38 and V39. In the case 'of the bus bar tubing 35 and 38. coolant connections 55. 56 and 51 are made so as to-provide circulation through the primary con.- ductor windings either in series through the en- 4. the drawings, consisting of at least 3 tube sections for each turn of the secondary. Reference p is made to Figure 7 for illustration of the inlet tire coil or in parallel arrangement employing' the connection through tubing 39 as a main inlet ,or outlet. As means for supporting the couplings 36 for these various terminals and taps a panel for deck board 49 is secured to the rear side of the transformer by means of oisetting blocks 4I attached to the brackets II and I2.

In order to increase the efiiciency of the unit :metal cooling tubes 42 are attached to the Aouter surfaces of the secondary turns, this tubing being concentric with the turns and, in the example ci and outlet connection of the coolant to the secondary tubing 42. As shown in this figure the bus bar structure and the connected terminals of the secondary adjacent the bus bars is formed with a plurality of ducts. As shown radial ducts 43 register with the adjacent ends of the coolant tubing 42 and lead to a manifold 44 which extends downwardly to an insulating tubing 45 Where connection is made to a second manifold 46 supplying radial ducts 41 and the attached coolant tubing 42 of the lower secondary turn I9. Similarly at the opposite ends of the lower turns radial ducts 48 pass into the manifold 49 and the upper turn ducts 50 enter manifold 5I. In this manner the coolant enters at 52 into the manifold 49 and is continuously circulated through the coolant tubing 42 attached to the secondary turns with final exit at the outlet 53. The cooling action of the secondary turns is accomplished by direct heat conduction from the secondary turns to the coolant. and for this purpose the coolant tubing should be metal and in close engagement with the metal of the secondary.

While the use of taps as 31 and 39 on the primary coil is useful in securing desired voltages on the secondary terminals there is a limit to the changes that may be secured eiciently in this manner. For example by means of the tapped arrangement as shown in Figures 2 and 3 including taps 31, 38 and 39 it is possible to secure a voltage variation on the secondary, assuming a twenty-three turn primary and one turn on the secondary, of around, 35 to 54 volts. However for heat treatment it is desirable to secure a voltage under certain conditions of use of as high as or more volts and I have been able to secure such a range of voltages, that is from approximately 35 volts to 107 volts by employing the two turn secondary hereinabove described and utilizing in conjunction therewith, and with the specific type of bus bar terminals mentioned, yoke members which, through adjustment in relation to the terminals of the secondary, permit either a parallel or series connection of the secondary turns. A plan view of these yokes is shown in Figures 7 and 8. As therein illustrated there are two yokes indicated respectively by the numerals 6l] and 5 l. Each yoke is approximately in the shape of a U with `one branch extended beyond the other so that if placed end to end with the long branch of one member in prolongation with the short branch of the other there is formed a rectangular configuration. This relationship is shown clearly in Figure 1 in the so-called series position. In this position the yoke is so mounted withv reference to the bus bars 2@ and 2i as to establish the circuit shown diagrammatically in Figure 12. In this gure it is apparent that currentfrom the bus bar 2!! by direct connection passes through the secondary turn I8 to the other terminal 23 and from this point by means of the yoke 60, as well as the yoke Iii, to the terminal 2'! of the lower turn I9. From this terminal the circuit leads around the turn I9 to the terminal 26 and bus bar 2l completing a series circuit through the secondary winding. This circuit is established through attachment of the short end of yoke 6i) directly to the terminal 23 by means of bolts 62 and attachment of the long end of the yoke 6I] directly to the lower terminal 2'! by means of the bolts 63. Also the lower yoke 6| is bolted at 64 to terminal 23 and at 65 to the terminal 2l.

In case it is desired to secure a parallel connection to the turns I8 and I9 the bolts 62 to 65 are removed and both yokes turned over so that what was formerly the upper or free side of the yokes is now the bottom or contacting side of the yoke. In this second position there are no bolt apertures corresponding to the bolts 62 to 65 and hence in this new position it is impossible to secure a series connection of the yokes to the bus bars and terminals. However there are additional apertures 66 in the upper yoke and 6l in the lower yoke which in the second position of the yokes register with bolt receiving apertures in the terminals 23 and 21 respectively and when bolts are placed through these apertures and at the same time additional bolts 68 and 69 placed through horizontal apertures in the yokes into engagement with the bus bars 20 and 2l respectively there is established a parallel connection as shown in Figure 8 and diagrammatically indicated in Figure 11. As shown in Figure 11 voltage applied to the bus bar 20 passes current in parallel through both turns I8 and I9 to the terminals 23 and 26 and thence to the bus bar 2|. There is thus accomplished a changeover from series to parallel as regards the turns of the secondary winding which may be advantageously employed to step up the voltage and secure a wide range of heat changes in accordance with the requirements of the heating unit.

While emphasis has been placed upon the voltage changing characteristics of the transformer it is pointed out that the structure involves a high degree of compactness and substantial simplicity in the relationship of the parts. There are structural details of value which are believed to be decidedly useful, for example the method of secondary cooling associated with the cooling of the primary turns insures improved efficiency in the operation of the transformer. Also in the construction of the insulation shell interior of the primary between the turns and cooling, I employ a novel means for obtaining simply the curved sectors l0 at the corners. These sectors are formed by taking a tube of insulation nbre of the approximate degree of curvature corresponding to the curvature of the primary turns at the corner and slitting the tube lengthwise in quadrants. Thus there is formed sectors of the desired curvature which may be inserted at the corners between flat strips of insulation indicated by the numeral 'Il to form the casing I6 of insulation inside the primary coil. Other novel details may also be considered as well as modifications of the specific showing, these various features however and the major conceptions of the disclosure being comprehended within the claim as appended.

What is claimed is:

In a transformer provided with secondary windings, the improvement comprising, in combination. a pair of coaxially-positioned, substantially-parallel secondary windings, each of said secondary windings being provided with a rst axially and outwardly-extending terminal positioned substantially parallel with the axis of the windings, said iirst terminals extending in insulated relationship, said rst terminals each making good electrical connection with one of said secondary windings at diagonally-opposite corners of the windings, each of said secondary windings being provided with a second terminal, one positioned at each other diagonal corner of the windings, said second terminals being in good electrical connection therewith, said iirst and second terminals being insulated from one another, each oi' said rst terminals extending outwardly beyond said second terminals and being provided with a shoulder, said shoulders extending outwardly substantially the same distance as said second terminals and lying in substantially single i-lat plane with the said second terminals, two U-shaped conductors insulated from one another to foi-rn an open broken rectangular configuration, said conductors physically tting around the outwardly-extending portion of the first terminals and adjacent said rst terminal shoulders and said second terminals, said U-shaped conductors each being provided with a long leg and a short leg, said legs of each conductor physically terminating at diagonally-opposite corners of the windings, said legs physically terminating adjacent said shoulders of said 'rlrst terminals in one iirst position adapted only for parallel relationship with said windings, said legs physically terminating adjacent said second terminals in another second position adapted only for series relationship with said windings, means for making only parallel electrical connection between said conduotors and said winding terminals in said iirst position and means for making only series electrical connection between said winding terminals and said conductors in said second position, whereby inversion of said conductors converts said secondary winding from a parallel relationship to a series relationship and vice versa.

HAROLD A. STRICKLAND, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 529,152 Zickerman Nov. 13, 1894 1,394,044 Stephens Oct. 18, 1921 1,789,229 Gebhard Jan. 13, 1931 1,791,934 Northrup Feb. 10, 1931 1,989,376 Northrup Jan. 29, 1935 2,181,899 Kennedy Dec. 5, 1939 2,321,999 Dalton June 15, 1943 2,341,943 Ogden Feb. 15, 1944 2,366,290 Rudd Jan. 2, 1945 2,368,505 Weldon Jan. 30, 1945 2,498,233 Baker et a1. Feb. 21, 1950 FOREIGN PATENTS Number Country Date 171,836 Great Britain Dec. 1, 1921

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