US 2885646 A
Description (OCR text may contain errors)
y 1959 K. c. BUGG ELECTRICAL TRANSFORMERS 2 Sheets-Sheet 1 Filed April 22, 1953 May 5, 1959 K. c. BUGG 2,385,646
ELECTRICAL TRANSFORMERS Filed April 22, 1955 2 Sheets-Sheet 2 IN V N TOR,
BY- gy G 5 199] ited States Patent ELECTRICAL TRANSFORMERS Kenly C. Brigg, Fort Wayne, Ind., assignor to Kendick Manufacturing Company, Inc., Fort Wayne, Ind., a corporation of Indiana Application April 22, 1953, Serial No. 350,397
1 Claim. (Cl. 336-421) This invention relates to a new and improved transformer and more particularly to a transformer having a flexible or deformable core.
More specifically the invention relates to transformers wound on toroidal or continuous cores which, after winding, may be deformed to bring core portions closer together to reduce the space occupied by the transformer and to increase its rigidity. The present invention is on the nature of an improvement on the invention disclosed in my application Serial No. 334,450, filed February 2, 1953, for Transformers.
The transformers are of a type including a generally toroidal continuous core formed of a plurality of layers or strands spirally wound; The strands or layers may consist of thin wires or ribbons of suitable iron or of strands or ribbons of suitable plastic carrying finely divided iron internally or externally thereof. Such wires, ribbons or strands are closely wound together to form a compact core which is flexible or deformable. The primary and secondary windings are wound on the core before the core has been substantially deformed and after the winding the core is deformed to provide a more compact and rigid transformer. By this method of construction a transformer is provided having a continuous core, a major portion of which is covered by the windings which are normally in one or two layers with portions of each winding exposed so that their characteristics may be adjusted after the winding and deformation of the core has taken place.
The uniformity of the effective permeability of a core and consequently the flux density is dependent upon the wires, strands or ribbons forming the core being maintained in uniform proximity to each other. It has been found that when deforming a transformer of this type there is a tendency for non-uniform separation of some of the layers or strands of the core when the core is held together only by the wire windings placed thereon. The wire is non-resilient and the relatively fine wire used in such windings may stretch to permit separation of core elements.
It is an object of the present invention to provide a transformer with a deformable core having resilient means for holding the core elements in close juxtaposition.
It is also an object to provide a transformer with a deformable core and a winding thereon of strands or filaments of resilient material adapted to maintain the elements of the core in close arrangement upon deformation of the core.
It is an additional object to provide a transformer of this character which is simple in design and construction and adapted for commercial production and use.
Other and further objects will appear as the description proceeds.
I have shown certain preferred embodiments of my invention in the accompanying drawings in which- Figure 1 is a plan view of a transformer before deformation,
Figure 2 is a section taken on line 22 of Figure 1, on an enlarged scale,
Figure 3 is a view similar to Figure 2, but showing a modified form of construction,
Figure 4 is a fragmentary view showing the core and windings,
Figure 5 is a plan view of a completed and deformed transformer,
Figure 6 is a fragmentary view similar to Figure 4, showing a modified form of construction,
Figures 7 and 8 are plan views of other forms of completed and deformed transformers, and
Figure 9 is a view similar to Figure 4 showing a further modified form.
In Figure 1 there is shown a plan view of a transformer after winding but before distortion. It will be apparent that the core is in the form of a toroid and, as shown, has three windings 12, 14 and 16 thereon. Various numbers of windings and various proportions of turns between windings may be used dependent on the particular characteristics of the desired transformer. While it is usually preferable to have only one or two layers of coils on transformers to be deformed, it will be understood that a greater number of layers may be used if required. The lower number of layers reduces the insulation requirements and the danger of shorting portions of the coils and also reduces their distributed capacity.
As shown in Figure 2, the winding 12 is superposed on an intermediate winding 18 which is wound directly on the core 20. The core 20 is shown as made up of a plurality of spirally wound laminations. These laminations may be formed of suitable iron having the proper characteristics for a core of a transformer of the character being wound. It is to be understood that the laminations will be quite thin so that the completed core may be deformed without difficulty. For very high frequency use the laminations may consist of finely divided iron incorporated in a non-conducting binder or applied to the surface of a non conducting film or ribbon by means of a suitable binder. Such powdered iron cores are well known in the art for high frequency use. As a specific example, a core may be wound of iron laminations onethousandth of an inch or less in thickness. The core may approximate one-fourth of an inch in height and thickness. In its original toroidal form, the core may have a diameter of several inches. It will be understood that the exact diameter will depend on the required circumference and the length of windings to be wound on the core. This specific example is to be understood to be illustrative only as the cores may be made over a wide range of sizes. In general, however, the invention is especially applicable to cores of small dimensions.
The intermediate winding 18 is formed of strands or filaments which are resilient and serve to retain the core laminations in intimate contact when the core is ultimately deformed as shown, for example, in Figures 5, 7 and 8. This Winding 18 may be formed of a variety of materials which are non-conducting and resilient and they will preferably be wound under an initial tension so that they are pre-stressed during the winding. As suitable materials there may be mentioned Teflon, nylon and other similar synthetic fibers or filaments or natural or synthetic rubbers or other resilient non-conducting material. Teflon is particularly suitable as it has a high thermal efiiciency and dielectric characteristics. It is highly desirable that the winding be made of strong, resilient material and that the winding be closely spaced. It is also preferable to use relatively small strands or filaments so that the core is held together by the turns of the winding at closely spaced points. The individual turns are thus not deformed substantially when the core is deformed 3; and maintain the core elements in close and uniform contact.
The form of construction shown in Figure 3 varies from that of Figures 1 and 2 in that the core is formed by a plurality of wires or strands 22 rather than by the fiat laminations of Figures 1 and 2. These wires or strands 22 are enclosed by the intermediate winding 24 similar to the winding 18 and a conducting transformer winding 26 is superposed on the intermediate winding 24. It will be understood that the size and number of the turns of the core 22 may be modified over wide limits and they may be formed of the various materials discussed in connection with Figures 1 and 2. For some purposes the core wires or strands may have an insulating coating 27, as shown in Figure 3, and if desired, the laminations of Figure 2 may be similarly insulated.
Figure 4 represents a fragmentary plan View of the construction of Figures 1 and'2 with portions of the windings removed in order to make clear the arrangement thereof.
One form of finished transformer, after deformation of the core, is shown in Figure 5. The transformer core and windings shown at 37 are initially in the general form shown in Figure 1. The transformer is elongated and one end is looped over a stud 41]. A stud 41 is spaced from stud 40 approximately the width of the transformer core and windings thereon. These studs 40 and 41 may be mounted in a temporary jig or may be incorporated in a cup-shaped housing having a bottom 43 and a circumferential wall 45. The core 37 is then wound upon itself in spiral form as shown, the portions of the core and windings being separated by a plurality of pins 47. These pins are preferably formed of non-magnetic and non-conducting material. The windings of resilient material on the core will maintain the core layers or strands in close and uniform relationship even when the core is deformed to the extent shown in Figure 5.
The construction shown in Figure 6 is similar to that of Figure 4 with the exception that the holding winding 54 is shown as formed of a strand having a rectangular or square cross section so that it continuously contacts the core 20. it is important, however, that the strand it} be relatively narrow as a tape or band will be so distorted when the core is deformed that it will not be continuously effective in holding the core elements together.
In Figure 7 is shown a plan view of a fully wound transformer which is not deformed to the extent of the transformer of Figure 5. The transformer of Figure 7 is merely changed from the circular plan view of Figure 1 to a generally figure eight configuration. The transformer 52 is held in this form by a binding 54 of nonconducting material. The binding 54 may be formed of the same types of material as the holding windings 18 of Figures 1, 2 and 4, winding 24 of Figure 3 or winding 50 of Figure 6.
The construction of Figure 8 differs from that of Figure 7 in that the central portion which is held together by binding 56 is much longer than that held together by binding 54 of Figure 7. The transformer is thus more elongated and can be located in a narrower space. It will be apparent that any suitable forms of binding means or holding or retaining means may be used in the constructions of Figures 7 and 8. The transformers are not distorted after the binding is applied and the binding does not serve to hold core elements together. Consequently tapes or sleeves of suitable material may be used for binding purposes.
in Figure 9 there is shown a fragmentary View of a transformer having a core 20 of the same character as that shown in Figures 2 and 4. On this core are interwound windings 61 and 63. The winding 61 is one of the conducting transformer windings, either a primary or secondary. The interwound winding 63 is formed of the same type of material as the windings 18 and 24 of Figures 2, 3 and 4. This winding 63 serves to uniformly separate the turns of the transformer winding 61 and to resiliently hold the layers of the core againts displacement upon deformation of the core. In some uses of transformers, a winding of this character is desirable in that the conducting winding is placed closely upon the core and the distributed capacity of the winding is reduced by the separation of the turns. It will be understood that the wire of the winding 61 will be provided with an insulating coating or the core 21) will have an insulating coating so as to insulate the winding from the core.
The present invention is not directed to the number or character of the conducting windings on the core of the transformer. They must be, however, either single layer windings or windings of a few layers only in order to permit the Wound transformer to be deformed and rendered more compact. Since compactness is an important feature of the invention, there will usually be no substantial portion of the core which does not carry a winding. The windings may be closely spaced, interwound, superposed or interleaved in accordance with Well known transformer practice and insulation of a kind and amount supplied depending upon potential differences between the windings and the windings and the core.
The various embodiments shown are to be understood to be illustrative only. Various types of deformable cores may be used and various types of resilient windings may be applied thereto. The purpose of the winding is to maintain the laminations or other substantially parallel elements of the core in close and uniform arrangement. The character, thickness and strength of the resilient winding will therefore be somewhat dependent upon the nature of the core and the tendency of core elements to separate when the desired deformation of the core is made. They will also be somewhat dependent to the use to which the transformer is put, particularly, for example, to temperatures to which it may be subjected and the voltages to be applied to the coils to be wound thereon. I therefore contemplate such modifications as come within the spirit and scope of the appended claim.
A transformer comprising a toroidal, flexible core including a plurality of adjacent turns of magnetic material, a close wound winding of narrow strands of fiexible, resilient, electrically non-conducting material forming a layer on the core and holding the core turns together, and conducting windings on the non-conducting winding layer, the core with windings thereon having portions located closely adjacent each other to form a compact assembly, and an additional non-conducting winding holding the transformer in its compact shape.
References Cited in the file of this patent UNITED STATES PATENTS