US1802371A - Electromagnetic device - Google Patents

Description

April 28, 1931. F. J. BULLIVANT ET AL ELECTROMAGNETI C DEVI CE Filed Aug. 5, 1928 Z4 29 IN x g/v T0735 ATTORNEY Patented Apr- 28, 1931 uu ran, STATES PATENT orrlca rumors 1. aunnxvm Anna-nan A. mum, or s'r. more, ,IIBSOUBI momemc navrcr:

, I Application flledAugunt 8, 1928. Serial No. 287,151. I

This invention relates generally to-electromagnetic devices and, more particularly, to a certain new and useful improvement in electromagnetic devices of a type especially.

' 6 adapted for use, as in radio, in the sending or receiving of electro-magnetic waves.

Our invention has for its prime object the provision in a device of the type stated of an inductance unit characterized by being. electrically and mechanicall protected and con-.

tained in an impermeab e moisture-free vessel, so as to have a calibrated electro-magnetic constant or constants.

Our invention has for another object the provision in a device of the type stated of means for adjustably var ing the fundamental of the windings an to, calibrate the same during the. process of manufacture to assure thatany one transformer will match any other having the same intended induc tance value. Our invention has for a further object the 'provision in a device of the type stated of shielding means disposed on the walls of the vessel and associated with its contained windings in fixed relation thereto, whereby the electro-ma-gnetic constants of the device. may be ermanently calibrated.

ur invention has for a still further object the provision in a device of the type stated of means whereby the inductance unitmay be easily and quickly incorporated in its associated circut or circuits, as by luggin the unit in, for example, a stan ard tu e socket or like receptacle.

And with the above and other objects in view, our invention resides in the novel fea-- tures of form, construction, arran ement, and combination of parts hereina er described and pointed out in the claims.

In the accompanying drawing, the figure illustrates'one form of an electromagnetic device embodying our invention, parts thereof being shown in section and other parts being broken away to disclose the construction of the device.

Referring now more in detail and by reference characters'to the drawing, which illustrates a preferred embodiment of our invention, our improved mductance unit may 1nclude a transformer A comprising an associated oup of inductances or electro-magnetic windings sealed in an impermeable vessel or chamber C preferably made of a dielectric, such as glass, having a moisture free content, as by being evacuated or filled with a dry, inert gas, and for convenience in handling and mounting the unit we may afiix a base D to-the bulb C, said base preferably carrying contact members connected to the transformer .A and adaptedto mate with a standard tube socket (not shown).

The transformer A may include a secondary inductance 10 wound on an insulatin form 11, and a primary inductance 12 wound on an insulating form 13 inserted within and preferably complementary to the form 11, with the outer or battery terminal B of the winding 12 adjacent one or the grid terminal G of the windmg 10, thus disposing the high potential terminals of the irespectlve inductubes in efiicient relationship for maximum magnetic coupling consistent with minimum capacity leakage between the windings.

The forms 11 and 13 may beof circular octagonal, square or other cross-section, an may be of tubular or skeleton construction, but we prefer to employ, as shown, circular tubular forms.

It isobvious that one, two, or more windperson constructing the device. The inductances maybe wound for use in radio-frequency or audiofrequency circuits, and 0th er dispositions and arrangements of the several windings, in addition to that shown on the drawings, will be obvious to those skilled in the art.

The moisture free vessel or chamber C includes a glass or like impermeable dielectri'c bulb 14 preferably formed at one or the base wall 15 thereof with an inwardly presented inte al transformer support 16, pref erably having a chamber 17 opening at its outer end through said base wall 15,

The vessel C may have an egg-shape, as shown in the drawing, or it may have the shape of a spheriod, an ovaloid, or other coo formation, and preferably is made moisturegas, as nitrogen, and immersing the inductance in said gas.

Having one end supportingly .passed through pairs of alining ferrules 18a, 18b,

disposed oppositely in and suitably cri-mped or otherwise secured to the respective forms 11- and 13, and the other end embedded in a cap 19 forming the inner end of the inductance support 16 and the endwall ofthe chamber 17, are opposing inductance supporting members or arms 20, suitably bent as best seen in the drawing, and fixed in the ferrules by any suitable means, although we prefer to employ solder, as at 21, whereby the transformer A is firmly endwise supported as a unit in the vessel C.

By thus supporting and sealing the transformer A in the closed vessel or chamber C,

the windings 10, 12, are protected from atmospheric influences, such as hygroscopic moisture, and particularly variations in the humidity of the atmosphere, the contents of said vessel or chamber being also moisturefree, thereby effectually preventing, from any cause, the formation of aqueous films on the windings, as well as at the same time preventing the deposition on the windings of films of dust or fume or the like. Such several films have the deleterious effect of increasing the inter-turn capacity leaka' of the windings, and of also increasing the ighfrequency resistance loss of the transformer, and as they vary from time to time, their growth and decay seriously deranges the constancy of the inductance value of windings exposed to their influence.

Furthermore, the windings being thus permanently and rigidly disposed in the containing vessel C, the latter forms a protecting envelope to prevent mechanical derangement or damage from handling or like causes.

The base D includes a molded cup or like structure 22 of insulating material, aving a filling of suitable insulating adhesive compound 23, in which is seated and secured the wall 15 of the bulb C, said wall 15 preferably having a frusto-conical shape as shown, presented interiorly said cup 22. Endwise presented from one or the bottom wall 24 of the cup 22 for mating with a suitable socket (not shown), such as a standard tube socket well known to those skilled in the art, are contact prongs F, P, B and G, adapted, respectively to be connected with appropriate filament, late, battery and grid or other leads, of t e circuit with which the inductance is associated.

The filament terminal F and the grid terminal G of the secondary winding are, re spectively, secured to the form 11 preferably by being passed through suitable apertures 25 there1n,-and are connected to the res c 21. Embedded in the cap 19 and filling 23 and passed through suitable insulating tubes 26 dlsposedin the chamber17, are conducttive ferrules 18a, preferably by the so der A ing leads 27, 28, respectively connecting the terminals F and G to the corresponding terminal lugs 29 of the rongs F and G embedded in and exten ing through the wall 24 of the base D. 5 I In like manner, the plate terminal P an the battery terminal B of the rimary winding 12 are, respectively, passed through suitable apertures 30 provided in the form 13 and are connected to connection In s 31 secured to the form 13. Conducti eads 32, 33, formed and disposed similar y to the leads 27,28, connect the terminals P and B through their respective lugs 31 to the terminal lugs 29 of their corresponding prongs P and B.

Preferably mounted on the form 11 adjacent to the filament end of the winding 10 and connected to the terminal F by a conducting lead 34 passed through an aperture 35 in said form 11, is a metallic capacity element or absorption plate 36, which acts to reduce the fundamental of" the secondary winding. In manufacturing the device, the late 36 may be adjusted suitably to alter the inductance value of the unit to match a predetermined standard value, so that any several transformers each having an associated group of inductances will have the same calibrated value in, for example, milli-henries, a condition referred to in the art as matched inductances. Exteriorly applied in a continuous conducting film, by electro-depositing, painting, spraying or dipping, to the exposed surface of the vessel C and baseD, is a metallic paint or like material 37, said paint being omitted from the wall 24, however, in order not to short-circuit the several prongs presented therefrom. A band 38 encircles the base D, contacting said conducting film 37, and is preferably connected to the filament prong F by a lead or conductor 39, said prong F being commonly associated with the negative or grounded side of the circuit in which the.

transformer is intended to be incor orated.

-. We prefer to form thefilm 37 o alumi.

num' paint forming an electro-magnetic absorption medium, whereby the transformer A is effectually shielded from exterior mag thereto-adjacent, and theshield being fixed with respect to the windings, the magnetic field of the transformer has a constant extent and value. I

In the u'seof our invention, the several windings maybe employed in, or associated with, any desired circuit in the usual manner well known to the art, the base D, having the several contact prongs, providing a convenient and practical means of connecting the windings to their appropriate parts of the circuit by simply plugging the device into a suitable socket or receptacle provided in the apparatus incorporating the circuit.

Thus it will be seen that we have provided a simple, neat, and convenient inductance unit or transformer, the windings of which are disposed in permanent and fixed relation in a moisture-free impermeable chamber or vessel, whereby the inter-turn capacity leakage of the windings is minimized, the windings are protected from corrosion or like deleterious influence of moisture, from the deposition of dust or fume or the like, and from mechanical derangement or damage in handling, hence the calibration of the transformer or inductance unit, once ef-- fected, remains thereafter at a constant value, an important and vital feature in radio-receiving or sending apparatus;

It is to be understood that changes in the form, construction, arrangement, and combination of the several parts of our new device .may be made and substituted for those herein shown and described without departing from the nature and principle of our iiivention.

Having thus described our invention, what we claim and desire to secure by Letters Pat ent is:

1. In combination, a base of insulating material, a sealed evacuated-glass bulb having a conical endwall presented into and secured to said base, an interiorly presented supporting member integrally extending from said endwall, a pair of spaced arms having one end embedded in said support, a pair of electro-magnetically associated inductance windings rigidly supported on the other ends of said arms, a plurality of contact prongs exteriorly presented from the end wall of said base, conducting members connected to said contact prongs and sealed through said supporting member for establishing electrical connection between said prongs and the respective terminals of said windings, a coat ing of conducting material applied to the exposed walls of, said base and said bulb, said prongs being insulated from said ooatin a. conducting band encircling said base for e ectrical contact with said coating, and means for electrically connecting said band with one of said prongs. r

2. In combination, a base of insulating material, a sealed evacuated glassbulb having an end Wall presented into and secured to said base, an interiorl presented supporting member extending rom said end wall, a pair of spaced arms having one end fixed to said support, a plurality of electro-magnetically associated inductance windings rigidly supbulb, said prongs being) ported on the other ends of said arms, a plurality of contact prongs exteriorly presented from the end wall of said base, conducting members connected to said contact prongs and sealed through said supporting member for establishing electrical connection between said prongs and the respective terminals of said windings, a coating of conducting material applied to the walls of said base and said insulated from said coating, a conductin and on the base for electrical contact with said coating, and means for electrically connecting said band with'one of said prongs.

In testimony whereof, we have signed our names to this specification.

FRANCIS J. BULLIVAN'I.

FRED A. MILLER.

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