US1680783A - High-frequency apparatus - Google Patents

Description

, Aug. 14,A 1928.

F. GUTZMANN HIGH FREQUENCYl APPARATUS Filed Aug. 2e, 192s Patented Aug. 14, 1928.

UNITED STATES 1,680,183 PATENT OFFICE.

FRITZ GUTZMAN'N, 0F CHARLOTTENBURG', GERMANY, ASSG-'NOR T0 C. LORENZ AK- TIENGESELLSCHAFT, F BERLIN-TEMPELHOF, GERMANY.

HIGH-FREQUENCY APPARATUS.

Appneafion mea August 2s, 192e, serial No.

The present invention has reference to 1mprovements in high frequency apparatus, 'and it relates more particularly to means for cooling iron-cored apparatus of this char- 5 acter, especially frequency transformers.

It is of recognized importance to properly cool electrical a. paratus containing magnetically stressedp iron, for the purpose of absorbing or dissipating the heat generated by the losses in the iron and in the windlng.

For this purpose, as is well known, transformers are bodily immersed in a flowing or stagnant cooling medium, such as oil.

My invention is directed to a method and means for cooling apparatus containlng magnetically highly stressed iron, such as for instance frequency changers used for stepping up a fundamental (natural) frequency to higher frequencies, keying or telephony chokes, and like apparatus for controlling high frequency currents, in whiclnthe eX- cessive iron heat, due to the high frequencies, must be actively removed to insure efficient operation of the device. o

According to my invention I forclbly cause a cooling medium, liquid or gaseous, to circulate between the iron core to be cooled and its Winding, so that the iron mass is completely surrounded by the cooling medium, whereas in the conventional oil baths, the oil reaches the iron surface only in spots through the interstices 1n the surrounding winding, leaving the prmclpal heat absorption to outwardly directed convection through the copper winding.

My invention will readily be understood from a description of the accompanylng drawing, in which the improvement 1s shown, by way of example, as applied to a 4.0 frequency transformer, Fig. l being a longitudinal section and Fig. 2 a cross-section through the arrangement. In Fig. 1 the winding is omitted.

In the two figures the reference' numeral l denotes the annular iron core formed of thin wires wound upon the cylinder 2, with the windings 3 and 1l arranged to form the primary and secondary of a toroidal coil, in well known manner. The iron core 1 is suitably fioatingly suspended within an annular cooling chamber 4, formed by the inner wall 7 and the outer wall 8, and side walls 9 and l0 respectively, and provided with indus and efflux ports 5 and 6 respectively. The

cooling chamber is preferably made of in- 131,576, and in Germany September 19, .1925.

sulating materialso that the windings 3 and l1 can be applied to it directly. The cooling oil is forced in throughV port 5, passes through the annular cooling chamber 4: in the direction of the arrows, and issues at 6, and is then preferably cooled and used over again in continuous circulation. The cooling medium, interposed between the iron core l and the windings 3 and l1 prevents to a high degree heat transference from iron to winding, and the windin space can thus fully be made use of wit out having to consider the admission possibility of the c001- ing medium to the core through the windin A further advantage is that now 'the loa 4 ing factor of the iron can be enhanced, that is to say the ratio between the'iron crosssection and the winding cross-section, since now the -oil` suiiiciently insulates the iron relative to the winding, which means also less danger of high stray voltage.

In addition to cooling the iron core by the positively moved cooling medium for cooling the iron mass, I immerse the transformer in the conventional oil bath for cooling the winding. The movement of the cooling medium through the cooling chamber surrounding the iron core may be caused by any suitable means, for instance by an electrically driven circulatory pump, which drive .with its connections to the cooling chamber form nol part of this invention and thus eed no special illustration or description ere.

The requirements for high frequency ktransformers differ from those for transformers adapted for ordinary frequencies, as follows The windings must be placed very close to the iron' core, to reduce stray fields. 95

The windings must be well insulated from `the iron core due to the high voltages involved;

(It so happens that good electric insulators'are usually also good heat insulators, im@ but this can be turned to advantage because heat insulation is advisable since the iron core is usually at a high temperature);

And `the usual materials such as cotton, silk and rubber must be excluded from the we transformer because they can only carry about C., just a fraction of the 300 C. at which high frequency cores normally operate. v

-Moreover, in order; to reduce the -stray Blf' eld the iron core is also made of very small dimensions so as to reduce the overall volume of the transformer winding to facilitate closeness of spacing.

All of the above diilicult requirements are met by the use of oil orthe electric and heat insulator and at the same time by the circulation of the oil Ato remove the heat resultant from iron losses due to eddy currents as described in detail above.

. What I claim is 1. In high frequency apparatus, an iron core, a cooling chamber spacedly surrounding said core, influx and elux ports in said chamber, and a Winding surrounding said chamber.

2. In high frequency apparatus, a cooling chamber of insulating material adapted for the passage therethrough of a cooling medium, influx and eiiux ports in said chamber, an iron core oatingly supported within'said chamber, and a winding surrounding Said chamber.

3. Al high frequency apparatus comprising windings and an iron` core and having a support to space the windings and core apart to permit a cooling fluid to be circulated between the iron core and windings in all-over contact with the core surface and having means to keep the cooling ilud out of contact with the winding.

In testimony whereof I aHiX my signature.

FRITZ GUTZMANN.

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