US1718080A - Transformer - Google Patents

Description

Patented June 18, 1929.

UNITED STATES PATENT OFFICE JOHAN ROMP AND WIEBOLD FRANS BRANDSMA, OF F-INDHOVEN, NETHERLANDS, AS- SIGN ORS TO N. V. PHILIPS GLOEILAMPENFABRIEKEN, A LIMITED LIABILITY COM- PANY OF THE NETHERLANDS.

TRANSFORMER.

No Drawing. Application filed February 15, 1928, Serial No. 254,603, and in the Netherlands March I This invention relates to transformers and more particularly small transformers, for example, those which are used in wireless telephony and telegraphy.

As a rule the windings of such transformers are composed of wires of copper. A disadvantage of copper is that its tensile strength is not great and its resistance to corrosion is insufficient.

The transformer according to the invention is characterized in that at least one of the windings is composed of wire which consists of an alloy of copper and silver. The tensile strength of such an alloy is greater than that of copper so that it is possible to draw the alloy down into wires having a smaller diameter than is possible in the case of copper. In addition the resistance to corrosion of the alloy is materially more satisfactory than that of copper.

Satisfactory results are obtained by the use of an alloy containing at least 94% of silver. As a result of the high content of silver there is no free copper left in the alloy so that practically no oxidation occurs. In addition the tensile'strength is materially increased. As the alloy moreover has only a very low ohmic resistance it serves admirably as material for the wire of the primary of low-frequency transformers used in wireless telephony and telegraphy.

The alloy may have added to it small quantities of nickel with the result that the probability of oxidation is further decreased so that in practice the wire proves still more resistant to external influences. As it has been established by experiments nobody has yet succeeded in forming alloys of nickel and silver so that the manufacture of silver nickel .wire is at present unknown. In the case of the alloy embodying the invention and containing at least 94% of silver it is possible to add nickel and thus to obtain an alloy capable of being drawn into wire of superior quality. This wire can be drawn out into a very fine wire so that it is possible for transformers wound with that wire to have very small dimensions. The wire being not or hardly liable to oxidation these transformers also have a very long life.

For transformer windings enamelled copper wire is mostly used. Its tensile strength is 30 kg/mm. The tensile strength is consequently materially lowered by the enamelling operation. According to the invention enamelled wire having a core consisting of an alloy of copper and silver may be used for transformer windings. The advantage of this alloy over copper consists in that the tensile strength is not lowered by the enamelling operation.

What we claim is:

1. A transformer for radio or like parposes, one of the windings thereof being composed of wire, which consists of an alloy of copper and silver.

2. A transformer for radio or like purposes, one of the windings thereof being composed of an alloy containing copper and at least 94% of silver.

3. A transformer according'to claim 2, in which the alloy includes small quantities of nickel.

4. A transformer for radio or like purposes, in which one of the windings is of enamelled wire the core of which wire consists of an alloy of cop er and silver.

In testimony whereo we afiix our signatures, at the city of Eindhoven, this 25th January, 1928.

J OHAN ROMP. WIEBOLD FRANS BRANDSMA.