US 1420989 A
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Description (OCR text may contain errors)
APPLlcAnoN man Nov. 15', 1912.
Patented June 27, 1922.
/n v en for.- W//fam Fond/War.
WILLIAM EONDILLER, OP NEW YORK, N. Y., AssIeNoR To WESTERN ELECTRIC COMPANY, INCORPORATED, or NEW YORK, N. Y., A CORPORATION or NEWYORK.
Specicaticn of Letters Patent. Patented une 27, 1922.
Application led November 15, 1917.` Serial No. 202,105.
i T all 'whom t may concern.'
y Be it known that I, WILLIAM lFONDIILER, a citizen Of the United States, residing at ,New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Transformers, of which the following is a full, clear,
`concise,1and exact description. i
This invention relates to transformers, and.
more particularly to transformers Or repeating coils for telephone systems wherein both high frequency talking current and comparatively low frequency ringing currents must be efficiently transmitted.
In order to effect long distance transmission, such as is now possible, it has been necessary to obtain greater and greater inductance stability in the apparatus used for telephone transmission. Such stability can only be obtained by improving the stability of the magnetic circuit o f all theelectromagnetic devices, which are used in the system. As is well known, magnetic material of high permeability, such as pure iron or` Isilicon steel, may besubject to large variations in permeability due to varying degrees of residual magnetism therein. heretofore used, such change in the perme" ability of the core material of the apparatus employed wasof little consequence, but in presentday systems it cannot be tolerated. For example, the cores of telephone repeating coils were heretofore composed'of a bundle of fine iron wires in ring form Or of a pile of thin annular plates. Such coils were sufficient both for the transmission of high frequency talking currents and also for the comparatively low frequency ringing current; but, due to trlanslent currents, which had access to the windings and due also to the comparatively large values of'ringing current, which sometimes owed theref through, the
permeability of the core material to the high frequency talking current varied considerably from time to time and interfered with the'stability of the system as a whole and, therefore, with long distance telephone transmission thereover.
The object of this invention is to providev a transformer or repeating coilvwherein the tendency of the magnetic circuit to change with respect to currents of telephonie amplitude is substantially overcome withouty greatly impairing the efficiency of the coil for transmitting both high frequency talking a section 5 `of high In systems ability ferro-magnetic material, that is, of a `material whose'permeability is substantially greater than unity, the relative length of the sections depending in each case result'to be accomplished.
This invention will be more lclearly understood by reference to the drawings, wherein:
Fig. 1 shows a repeating coil partly in section embodying this invention, and Figs. 2 and 3 show two forms which the low permeability magnetic material may assume.
In Fig.- l is shown a repeating coil in which the magnetic circuit 4is composed of ermeability magnetic material, such as silicon steel where the initial permeability at low magnetizing forces is approximately 500 and a section of` low permeability magnetic material such als finely divided ironl particles, having an initial permeability at low magnetizing forces of approximately 60, intermediate the ends of section 5. Over this magnetic cir- 4 upon the cuit arel wound superimposed windings 7 and 8, which are-in inductive'relation to each other and constitute `inductively connectedwindings of the repeating coil.
. The "short sectin may take either of the forms shown in Figs. 2 and 3. In Fig. 2 itis shown in the shape of a washer and may be'composed of finely divided iron particles, individually` insulated and formed into a compact. mass by hi h pressure, in accordance with' a method escribed and claimed in the U. S. Patent to Speed, No. 1,274,952,
issued August 6, 1918. The modification'of Fig. 3 consists of a washer 9, formed of insulating material and. of the desired shape, having a plurality of lholes 10 therethrough which are filled with a low permeability magnetic materiall of composition, for example, the same as that'use'd for the washer of Fig. 2.,
The advantage vof such a composite core is dependent upon the demagnetizing effects of ends in a magnetic circuit and upon the decreased reluctance of the low permeability section over what it would be were non-magnetic material used instead of the low permeability material hereinbefore described. The effect of ends in the high permeability section is to materially improve its inagnetic stability with respect to telephone currents. Consequently, the impedance Stability of the telephone circuit as a whole, is greatly improved. The reduced reluctance of the low permeability section of the magnetic circuit substantially eliminates the tendency for lines lof force to leak out of the winding, and, consequently, substantially eliminates any losses from that source in surrounding conducting material, as well as crosstalk due to the proximity of other telephone transformers. The effect, then, of this construction results in a highly efficient repeating coil having a stable magnetic circuit with minimum leakage tendencies.
lVhile the invention has been described in connection with a repeating coil having a ring core composed of a long section of silicon steel plates and a shortsection of finely divided iron, it is to be understood that other materials of similar characteristics can as well be used, and that the form of the sections can as well be other than those shgwn inl the drawings.
What is claimed is:
l. A transformer for telephone systems having a core of high permeability silicon steel having a comparatively short gap therein and a spacer of finely divided iron for said gap.
2. A transformer for telephone systems having a compositecore of high permeabilL ity magnetic material having a transverse gap and a section of low permeability magnetic material located in said gap.
3. A transformer for Vtelephone systems having a core comprising alternate long and short sections, said long section consisting of high permeability magnetic material, and said short sections consisting of low permeability ferro-magnetic material.
4. A transformer for telephone systems having a ring core, a plurality of magnetically coupledwindings on said core, said core comprising a comparatively long section of high permeability magnetic material, and a short section of low permeability ferro-magnetic material.
5. A transformer for telephone systemsv having a ring core, a plurality ofmagnetically coupled windings on said core, said core comprising a comparatively long section of high permeability magnetic material, and a short section composed of finely divided iron. y
6. A transformer for telephone systems having a ring core, a plurality of magnetically coupled windings on said core. said core comprising aI comparatively long section of high permeability magnetic material, and a short section of non-magnetic insulating solid material having holes filled with finely divided iron.
7. A transformer for telephone systems having a ring core, a plurality of magnetically coupled windings on said core, said core comprising high permeability magnetic material having a gap and a spacer for said gap comprising finely divided individually insulated iron particles.
In witness whereof, I Ahereunto subscribe my lname this 12th day of November, A. D.,
' W'ILLIAM FONDILLER.