US3201731A

US3201731A - Transformer core and lamination therefor

Info

Publication number: US3201731A
Application number: US240276A
Authority: US
Inventors: Robert C Baenziger; John F Rieger
Original assignee: ELECTRO NETIC STEEL Inc
Current assignee: ELECTRO NETIC STEEL Inc
Priority date: 1962-11-27
Filing date: 1962-11-27
Publication date: 1965-08-17
Anticipated expiration: 1982-08-17
Also published as: GB1045402A; GB1045401A; GB1045403A

Description

Aug. 17, 1965 R. c. BAENzlGER ETAL 3,201,731

TRANSFORMER CORE AND LAMINATION THEREFOR Filed Nov. 27, 1962 65 647 [m1101121 lam/0N *1., l l 44 j ZH @#5246150 Y 60 fb 1 H6474@ HHH f 29: |smrm-n lmroncl mmm al 5TAT|O-A umm u y@ @i [l M1111 H W1 m Wm [i [I @01] 721] 96 I L I y.

' INVENTORS, -befZCQ/zg gen A BYJOmj/iwger,

United States Patent O .li Ja.

3,201,731 TRANSFRMER CURE AND LAMINATEN ,THEREFGR .Robert C. Baenziger, Northbrook, and Sohn F. Rieger,

Wilmette, Ill., assigner-s to Electro-Natie Steel, Inc., .Schiller Park, Ill., a corporation of Illinois Filed Nov. 27, 1962, Ser. No. 240,276

2 Claims. (Cl. 336-212) The present invention relates itself to electromagnetic induction apparatus, and more particularly to the form and manufacture of laminations for stacked transformers.

Every electromagnetic induction device is a flux generator and from every flux generator there is a certain beam deflection system. With the current trend rtoward stressed dellection systems; the problem created by flux is critical. It is to this general problem of preventing flux leakage from transformer cores in the most effective Vand least expensive way that the present invention directs itself.

There are several Ways of controlling the leakage flux so as to avoid stray flux fields, one of which is to decrease the flux density in a transformer by increasing ,the core size. But, of course, this is contrary .to the trend toward compactness and results only in a larger and more expen- Copper bands around the core tend to containthe flux lines and reduce liux leakage and orientation of the transformer core on the television chassis may also avoid stray flux fields but thesesolutions are limited in their effectiveness. One of the best methods that has been devised for solving'this problem of flux leakage is to completely enclose the transformer in a shield or can whereby all the flux lines are contained Within the can. Although effective, this manner of solution is expensive.

It has now become a practice to make power transformers in radio and televisionV circuits of stacked interleaved U and I laminations, which transformer is enclosed construction is expensive not only in that itincludes the extra element of a can but also in that in making the interleaved stacking it is necessary that the laminations be individually'handled. Thus, although the resulting core type transformer is effective for reducing component size, it is considerably more expensive in material cost and in labor expense than is preferred for television power transformer usage.

A general object of the present invention is to provide a new and 'improved stacked lamination transformer core structure and lamination therefor permitting of relatively inexpensive construction, ease of assembly and minimum flux leakage.

A further object of the invention is to provide a lamination form adapted for use in a stacked lamination transformer core structureand which lamination is of a configuration so as to permit the stamping out of the metal strip with no substantial loss in material.

An additional object of the invention is to provide a method of making the novel lamination in accordance with the invention from a single strip of magnetically permeable metal and without the wasting of any significant amount of metal material.

A specific object of the invention is to provide a modified U shaped lamination includingtwo leg portions joined by a bight portion wherein the legs may be of any length 3,2@L73l Patented Aug. y17', 1965 within the limitation that one leg is shorter than the other leg by approximately the width of the bight portion. Accordingly, in stamping out this lamination from a rectangular Vportion of a metallic strip it is possible to interdigiytate the positions of the modified U blanks so that in the punching of one blank from the strip, that which is left is an identical modified U blank. Laminations so formed are stacked into two complementary stacks, windings, inserted over the legs of one stack and the two stacks butted, thereby to forma butted U-U core type transformer for Vwhich the distributed windings overlie the butted joints thereby reducing of flux leakage and substantially avoiding stray flux lines. It is obvious that a shell type can be formed from two core type structures with the same advantages in caseof assembly and reduction of flux leakage.

Further objects and features ofthe invention pertain to the particular arrangement and structure whereby the above identified and other objects of the invention are attained. The invention, its structure, its method of manufacture and its arrangement for use will be better understood by reference to the following specification and drawings forming a part thereof, wherein:

FIGURE l is a View in ,perspective of a modified U lamination in accordance with the present invention;

FIGURE 2 is a perspective view of two complementary stacks of laminations as shown in FIGURE 1 split and arranged for butting so as to form a core type transformer;

FIGURE 3A is an elevational View of a core type transformer made from the laminations of FIGURE l;

VFIGURE 3B is an elevational view of a shell type transformer made from the laminations of FIGURE l;

FIGURES 4A and 4B illustrate two methods for stamping blanks in accordance with the invention from a strip of magnetically permeable material; and,

FGURE 5 illustrates another method of stamping blanks in accordance with the invention from a strip of magnetically permeable material.

Referring first to FIGURE 1, there is shown therein in perspective view a lamination 10 made up of integrally formed leg portions 12 and l11i and a lbight portion '1.6. .The laminati-on 1G is a blank stamped from a thin sheet of magnetically permeable metallic material for which the magnetic grain may or may not be oriented depending upon the cost requirements and the magnetic circuit standards to be met. The leg l2 is Iof a length l and the bight portion 16 is of a width a. Preferentially then the leg portion 14 is of a length l-a, with the legs |14 and y12 each being of a width b. The bight portion lo is of a length 3b, las shown. Where grain oriented material is employed it may be that it will be preferred to compensate for the difference between ingrain and cross-grain permeability by making the crossgrain `dimen-sion larger than the in-grain dimension. For example, if the lamination 10 were a blank of material grain oriented in the direction indicated by the arrow 18 and if it were desired to compensate for the difference between the magnetic permeability of the in-grain and cross-grain areas, the dimension a would be greater than the dimension b by an amount substantially in proportion to the ldifference between in-grain and crossgrain permeability of the magnetic material.

The `manner in which the laminati-ons 1li illustrated in FIGURE 1 are stackedin order to form a butted core is illustrated in FIGURE 2. Therein the laminations 1li are arranged in la `first stack 22 and in a second stack 24 wherein the stack 22 provides a butting face 26 associated with the leg portions 12 and a butting face 28 associated with the leg portions 14, and the stack 24 provides a butting face 36 associated with the leg portions 1-4 and a butting face 33 associated with the leg "otherwise illustrated in FIGURE 2 is `nally assembled is illustrated in FIGURES 3A and 3B. In FIGURE 3A there is shown a core type transformer :assembled from stacks `ZZA and 24A of laminations as shown in FIGURE 2 and including transformer windings tti and ft2 overlying the abutting faces Zeit-36A and 28A-3era, respectively. The exact naturey of the windings tti ard 42. :are not so important as the considerati-on that they do overlie the abutting faces thereby substantially reducing the leakage iiux and confining the lines of stray iiux to the transformer configuration. The .stacks Z2 and 2t may be secured into place by any convenient bracket mean-s which will bring the abutting faces into intimate Vassociati-on. Of course, theV smoother and the more intimate the association between the abutting faces the less the air gap and the less the fiux leakage.

In FGURE 3B there is shown a shell type transformer assembled from stacks `22B and 24B an-d stacks 212C and Zit-C and @ranged to provide a common center leg 4d and two outerl legs i3 and 49. The center leg 46 has `overlying it and the abutting faces thereof a transformer winding 52 and the legs 413 and/t9 have overlying them and the abutting faces thereof transformer windings 5t and 56. The manner of mounting is optional, it being important only that the stacks be arranged to provide a substantially gapless and intimate mating between abutting faces.

lFIGURE 4A illustrates the procedural steps that take place -in` stamping the laminations iti frorna strip of magnetically permeable material Sti. In this particular arrangement and in keeping with the definition set forth relative to FTGURE 1, the strip of material is selected to be of a width 4b. It is fed into a punch press provide-d with two simultaneous punching operations at consecutive punching stations. Thus, at the first stamping station, as illustrated in FIGURE 4A, the strip 5% is operated upon to punch out the blank di) corresponding identically to the laminations i@ shown in FIGURE l. Thereafter, the punch press operates so as to shift the punched strip to station 2 whereat the nal punching operation takes place to severV the blank 62 from the ystrip Sti and complete the punching operation. At the same time that blank e2 is being punched at station 2 another lblank 6@ is being punched at station 1. Thus, the punching operation is quick and efficient and produces blanks for laminations `without waste of any strip material. FIGURE 4B illustrates another punching arrangement where a strip of material Sti of a width l+a is subjected to ay single punching operation whereby the blank 64 is stamped out leaving as a residual the blank 66, each of y.a configuration as shown in FIGURE 1.

A similar but more complicated punching operation is illustrated by the representation of FIGURE 5. Therein the selected punch press is designed to have at least four active punching stations whereby punching operations can be carried out simultaneously. Specifically, again a strip Sti ofl a width 4b is fed intoV the punch press, not shown, and progresses therethrough in seven stations. At station A, guide slots 7d, '712, 74, '76, 78 vand Sti are punched into the strip, whi-ch slots serve not only for alignment purposes during the subsequent stamping operations but accurately position and identify the abutting faces on the lamination product. At station B the first blank stamping operation takes place Wherein the blank 82 is punched from the strip. At station C a second punching operation takes place wherein the blank S4 is punched from the strip and at station D a `final stamping ope-ration takes place wherein theblank l f Se is stamped from the strip leaving in addition the blank 83.

In the stamping operation of FIGURE 5 the punch ing of the guide slots does create some nominal waste ibut it doesy permit a better alignment and does provide for a greater exactitude in the punching of the surfaces that will form the abutting faces of the transformer core stacks. Other punching operations maybe performed such, for example, as mounting holes in the laminations, if desired, and a shaving operation on the face of the guide `slots that will form abutting faces of the transformer core. The first operation may be comple-ted in either of the arrangements of FIGURES 4 `and 5 by the inclusion of an extra preliminary punch* ing station. Similarly, the shaving operation m-ay be added to the arrangement of FIGURE 5 'by including between station A and station B :a separate shaving station.

In practice, laminations suited for use in the construction of television power transformers have been stamped from strip steel of AISI grade M27 and of a 24 or 26 gauge. Core type transformers constructed in accordance with the scheme of the present invention are approximately three inches square with a one inch square central window. This physical size may be varied according to the permeability of the selected material and the desired power capacity of the transformer to be constructed from the core.

From the foregoing it is clear that there has been provided herein a new and improved core construction and lamination therefor wherebyy a core type transformer can be constructed from laminations stamped from a strip of magnetic permeable material without waste of that material and wherein, specifically, the laminations are of a modified U shape with one leg shorter than the other leg by a dimension corresponding to the width of the bight portion therein. Additionally, through use of such laminations it is possible to derive a transformer construction wherein windings carried on opposite legs of the transformer enclose and encompass the abutting faces of the lamination stacks in a manner so as to substantially reduce ux leakage and prevent the formation of stray iux lines. rThus, there is presented not only a simple and eicient lamination and method of making the same, but there is formed a transformer which can be made of relatively inexpensive permeable material. The principles described herein may also be employed in larger dimensions for the purpose of making laminations for high kv-a. power transformers. Y

Although the arrangement described herein is considered at present to be preferred, it is understoodthat it merely exemplary of the principles of the invention and that variations and modifications may be made therein. It is intended to cover in the appended claims all such variations and modifications as fall within the true spirit and scope of the invention.

We claim:

1. A core type transformer which comprises a first stack of laminations including a first leg portion, a second leg portion and a bight portion joining said iirst and second leg portions; said first leg portion of said stack being longer than said second leg portion by an amount corresponding substantially to the width of said bight portion; said laminations of said first stack being joined so that the free ends of said'stacked first and second leg portions define a planar mating face; a second stack of laminations including first leg portion, a second leg portion and a bight portion joining said leg portions and constructed so as to complement the coniiguration of said firstl stack of laminations; said laminations of said second stack being joined so that the free ends of said stacked first and second leg portions define a planar mating face that complements the mating face dened by the free ends of said stacked leg portions of said first stack of laminations; Said mating faces of said iirst and second leg portions of said respective stacks being intimately abutted so that a substantially rectangular core configuration is defined by said abutted stacks; and first and second transformer windings overlying and encompassing respective ones of said abutted mating faces and adjacent segments of said stacked leg portions so as to minimize leakage flux and conne lines of stray flux to said core type transformer during the operation thereof.

2. A shell type transformer which comprises `a first stack of laminations including a first leg portion, a second leg portion and a bight portion joining said first and second leg portions; said lirst leg portion of said stack being longer than said second leg portion by an amount corresponding substantially to the Width of said bight portion; said laminations of said first stack being joined so that the free ends of said stacked rst and second leg portions define a planar mating face; -a second stack of laminations including a first leg portion, a second leg portion and a bight portion joining said leg portions and constructed so as to complement the configuration of said first stack of laminations; said laminations of said second stack being joined so that the free ends of said stacked first and second leg portions define a planar mating face that complements the mating face defined by the free ends of said stacked leg portions of said first stack of laminations; said mating faces of said first and second leg portions of said respective stacks being intimately abuttcd so that a substantially rectangular core configuration is defined by said abutted stacks; third and fourth stacks of laminations constructed and abutted so as to complement the abutted configuration of said iirst and second stacks; said third and fourth stacks of lamii nations being joined to said first and second stacks so as to provide a rectangular transformer configuration having a center leg of greater width than the two end legs thereof and having the planar mating faces of said leg portions of said first and second abutted stacks that define a portion of said transformer center leg offset from the planar mating faces of said leg portions of said third and fourth stacks that define the remaining portion of said center leg of said transformer; and a plurality of transformer windings overlying and :encompassing respective ones of said abutted mating faces and adjacent segments of said stacked leg portions that define said transformer legs so as to minimize leakage iiuX and confine lines of stray flux to said core type transformer.

References Cited by the Examiner UNITED STATES PATENTS 696,953 4/02 Everest 336-217 755,766 3/04 Hall 336-212 X 1,599,842 9/26 Schneider 336-217 X 1,805,534 5/31 Troy 336-216 1,834,898 12/31 Boyajian 336-216 2,909,138 10/59 Lawson 13-116 2,938,150 5/60 Kniel 336-215 X 3,034,466 5/62 Brandes 113-116 FOREIGN PATENTS 1,035,752 8/55 Germany.

JOHN F. BURNS, Primary Examiner.

W. A. HIRTZ, Examiner.

Claims

1. A CORE TYPE TRANSFORMER WHICH COMPRISES A FIRST STACK OF LAMINATIONS INCLUDING A FIRST LEG PORTION, A SECOND LEG PORTION AND A BIGHT PORTION JOINING SAID FIRST AND SECOND LEG PORTIONS; SAID FIRST LEG PORTION OF SAID STACK BEING LONGER THAN SAID SECOND LEG PORTION BY AN AMOUNT CORRESPONDING SUBSTANTIALLY TO THE WIDTH OFSID BIGHT PORTION; SAID LAMINATIONS OF SAID FIRST STACK BEING JOINED SO THAT THE FREE ENDS OF SAID STACKED FIRST AND SECOND LEG PORTIONS DEFINE A PLANAR MATING FACE; A SECOND STACK OF LAMINATIONS INCLUDING FIRST LEG PORTION, A SECOND LEG PORTION AND A BIGHT PORTION JOINING SAID LEG PORTIONS AND CONSTRUCTED SO AS TO COMPLEMENT THE CONFIGURATION OF SAID FIRST STACK OF LAMINATIONS; SAID LAMINATIONS OF SAID SECOND STACK BEING JOINED SO THAT THE FREE ENDS OF SAID STACKED FIRST AND SECOND LEG PORTIONS DEFINE A PLANAR MATING FACE THAT COMPLEMENTS THE MATING FACE DEFINED BY THE FREE ENDS OF SAID STACKED LEG PORTIONS OF SAID FIRST STACK OF LAMINATIONS; SAID MATING FACES OF SAID FIRST AND SECOND LEG PORTIONS OF SAID RESPECTIVE STACKS BEING INTIMATELY ABUTTED SO THAT A SUBSTANTIALLY RECTANGULAR CORE CONFIGURATION IS DEFINED BY SAID ABUTTED STACKES; AND FIRST AND SECOND TRANSFORMER WINDINGS OVERLYING AND ENCOMPASSING RESPECTIVE ONES OF SAID ABUTTED MATING FACES AND ADJACENT SEGMENTS OF SAID STACKED LEG PORTIONS SO AS TO MINIMIZE LEAKAGE FLUX AND CONFINE LINES OF STRAY FLUX TO SAID CORE TYPE TRANSFORMER DURING THE OPERATION THEREOF.