US2206250A - Transformer - Google Patents

Description

J. V. FILL TRANSFORMER July 2, 1940.

Filed March 25, 1935 1 N VEN TOR. John 1/. F

36 37 ATTORNEYS.

Patented July 2, 1940 UNITED STATES FATENT OFFEQE TRAN SFORMER John V. Fill, New York,

N. Y., assignor to'Ferro- Application March 25, 1935, Serial No. 12,877

16 Claims.

This invention relates to coupling transformers adapted to pass only a predetermined, narrow band of frequencies, which find employment principally in superheterodyne radio sets for passing intermediate frequency voltage from one stage to another. The invention may be used advantageously, however, for effecting any radio frequency or other high frequency coupling.

It is an object of the invention to provide a transformer structure which can be assembled economically and accurately, and in which the circuits of the successive stages can be adjusted precisely to desired resonance characteristics.

It is a further object of the invention to provide a novel method whereby devices of the class indicated may be accurately and economically manufactured.

Other objects and advantages will hereinafter appear.

In the drawing forming part of this specification Figure l is a side elevation, with parts in section, of a structure embodying features of the invention, the stucture being shown as turned on its side;

Figure 2 is a side elevation of the same structure illustrated in Figure 1, but with the shield can removed, and turned around so as to expose the opposite side to view;

Figure 3 is a View in rear elevation of the structure of Figure 2;

Figure 4 is a sectional, detail view of the transformer supporting structure, and

Figure 5 is a plan view of an insulating spacing plate employed in the device.

The transformer illustrated comprises a sleeve I of paper or other suitable insulating material of accurately predetermined transversedimensions. The sleeve is desirably cylindrical, but may be made polygonal if desired, and its walls are of substantially uniform thickness. Ferromagnetic core members 3 and 4 are inserted into and fit snugly within the sleeve, the core member 3 being placed near one end thereof, and the core member 4 being placed at a predetermined distance from the core member 3. The core members are desirably composed of powdered iron, the iron particles being united by means of a suitable insulating binder and molded.

A rod 5 of wood or other suitable insulating material is passed through bores 6 and l of the core members 3 and 4. The rod fits the core members snugly so that the core members cannot shift longitudinally of the rod. The preferred method of making the assembly is to posi- (Cl. 250--l6) tion the core members properly upon the rod 5 and then insert the rod with the core members mounted upon it into the sleeve I. The axis of the rod coincides with the axis of the sleeve l.

After the assembly has been thus effected it is placed in a coil winding machine which winds two coils 8 and 9 upon the sleeve simultaneously. The winding is effected by rotation of the sleeve about its axis, and the wire supplying and guiding devices are so spaced, arranged, and moved that identical coils are caused to be wound about the middle portions of the core members 3 and i. Desirably the same kind of wire is employed for both coils and the winding of the coils is initiated simultaneously and terminated simultaneously. After the wiring has been completed the assembly is dipped in molten Wax which, upon solidifying, prevents penetration of moisture. The coils need not be identical in all instances, since it is sometimes desirable to employ coupled coils bearing different numbers of turns so as to step the voltage up or down.

A reduced, threaded stem portion Iii extends from an end of the rod 5, in axial alignment with the rod. An insulating condenser supporting block 42 is impaled upon the stem H3, and a nut I3 is screwed onto the stem to clamp the block I2 in place. The nut I3 and the shoulder of the rod 5 at the inner end of the stem l0 jointly fix the position of the block I2 longitudinally of 130 the stem Ill.

The block I2 carries small, adjustable condensers M and I5 at opposite sides of the stem Ill. The condenser I4 comprises alternate conductive and insulating plates i6 and H. Alternate conductive plates of the condenser are connected to a terminal I8 and the other alternate conductive plates are connected to a terminal H9. The outermost conductive plate" of the condenser is resilient and is bowed. A screw 29 is passed through the condenser plates without contacting them, and through the block I2, a nut 2| is threaded onto the screw 29. The nut H is received in a recess in the block and is held by 45 the walls of the recess against rotation. Thescrew is separated from the outermost conductive plate of the condenser by an insulating washer 22 and a metallic washer 23. The screw and nut serve both to hold the condenser parts in place and to adjust the capacity of the condenser. The terminal 13 is connected to the outer end of the coil 8 through a conductor 22a, and the terminal is is connected to the inner end of the coil 8 through a conductor 23a. The conductors 22a and 23a, are preferably wire ends integral with the winding of the coil 8.

The condenser 15 is desirably identical in construction with the condenser it, and will not be described in detail. It may, however, be made to cover a different range of capacities if desired. Alternate conductive plates of the condenser l5 are connected to a terminal E i, and the other alternate conductive plates of the condenser are connected 'to a terminal 25. The terminal 2 1 is connected to the inner end of the coil 9 through a conductor 25, and the terminal 25 is connected to the outer end of the coil 9 through a conductor 27. The conductors 2% and 27 are desirably integral end portions of the winding of the coil 9.

Conductors 28 and 29 are connected respectively to the terminals i8 and i9 and form elements of the stage of which the coil 8 and condenser I4 form parts. Conductors'3i] and 31 are connected to the terminals 24 and 25 and form elements of the stage of which the coil ii and the condenser i5 form parts.

Spacer plates 32 and 33 of insulating material are mounted upon the sleeve 5, the former substantially against the forward or upper face of the coil 9, and the latter substantially against the rear or lower face of the coil 8. The spacer plates 32 and 33 are of insulating material, being desirably made of paper.

The spacer plate 32 is seen in Figure 5. It is provided with a central opening 34 shaped to fit the sleeve I. A slit 35 extends from the opening 34 through the periphery of the plate so that the plate may be deformed and passed around the sleeve I after the other described parts have been fully assembled. Adjacent each corner of the plate provision is made of an open ing 36 for receiving one of the conductors 23, 29, 30 and 3|, and each of these openings communicates through a slit 3'! with the periphery of the plate so that the conductors can be inserted into the openings 36 through the marginal portions of the plate.

The spacer plate 33 may be or identical construction but, as shown, this spacer plate not provided with the slits 35 and 37!.

The spacer plates support the conductors 28, 29, 30 and 3| at predetermined equal distances from the coils and from one another and cause them to extend in parallelism with the common axis of the coils. The inherent couplings between the conductors and the coils are therefore substantially constant as the conductors cannot shift position and thus cause changes in the resonant frequencies of the coils.

When the parts have been assembled as described, they are inserted into a metallic, shielding housing 33 which substantially fits the insulating block i2 and the spacer plates 32 and 33. The stem iii is passed through a central opening in the top of the housing and is secured to the housing by threading a nut 39 onto the stem. The housing is made long enough to extend a substantial distance beyond the end of the sleeve i, and hence serves to space the lower coil 8 a substantial distance away from the supporting base or chassis section :10 upon which the housing is mounted. The coil 8 is thus protected against undesired inductive interference. The housing is provided with threaded legs M which are passed through the supporting base and secured to the base by means of nuts 42.

The housing is provided with openings 33 in its top face through which access may be had to the adjusting screws 72E of the condensers M and l5 after the parts have been fully assembled as described.

The structure shown and described is capable of being made very accurately and yet inexpensively. Because of the high degree of accuracy which can be secured, receiving sets employing the disclosed structure may be made to possess a very high degree of selectivity. In this connection it it of particular importance that the coupling between the coils may be made of just the proper value to assure the maximum eiiiciency of transmission while avoiding the detuning of one circuit by the other.

I have described what I believe to be the best embodiments of my invention. I do not wish, however, to be confined to the embodiments shown, but what I desire to cover by Letters Patent is set forth in the appended claims.

I claim:

1. In a high frequency coupling device for radio sets, in combination, an insulating support, an insulating rod and means securing one end thereof to said support, a pair of ferromagnetic cores each comprising powdered magnetic material having the form of a cylinder with a bore extending axially therethrough, said cores being mounted upon the rod at predetermined positions longitudinally thereof, a single insulating sleeve conforming to and snugly fitting the cores, transformer coils mounted upon the sleeve around the mid-portions of the respective cores, and means for mounting said support on a chassis.

2. In a high frequency coupling device for radio sets, in combination, an insulating sleeve having a wall of substantially constant thickness, a pair of ferromagnetic cores each comprising powdered magnetic material having the form of a cylinder with a bore extending axially therethrough, said cores being mounted in the sleeve in predetermined positions longitudinally thereof, transformer coils fixed upon the sleeve around the mid-portions of the respective cores, and means including a rod extending through said sleeve and secured to said cores for mounting the assembly.

3. In a high frequency coupling device for radio sets, in combination, an insulating sleeve having a wall of substantially constant thickness, a pair of ferromagnetic cores each comprising powdered magnetic material having the form of a cylinder with a bore extending axially therethrough, said cores being mounted in the sleeve in predetermined positions longitudinally thereof, identical transformer coils wound in situ upon the sleeve around the respective cores, and means including a rod of non-magnetic material snugly fitted within said cores for mounting said coupling device on a support.

4. A high frequency transformer for radio sets comprising a block of insulating material, a paper insulating tube and means mounting the same upon said block, a pair of ferromagnetic cores mounted in predetermined spaced relation within said tube, a transformer coil at the exterior of and fixed to said tube around the mid-portion of each core, conductive members extending from the terminals of said coils, and spacer plates of insulating material mounted on said tube adjacent said coils and extending outwardly beyond said coils, said spacer plates having openings for receiving and retaining said conductive members in fixed position with respect to said coils.

5. In a transformer for radio sets, an insulating block, a pair of adjustable condensers moun1;

ed on one face of the block, a rod of insulating material secured to and extending from the opposite face of said block, a pair of tubular cores of magnetic material fitted upon said rod in axially spaced relation, a pair of coaxial transformer coils mounted about and insulated from the respective cores in predetermined spaced relation, said condensers being shunted across the respective coils, a shield housing having a top through which said rod extends, means threaded on the extended end of the rod to secure the same to the top of said housing, thereby to suspend said rod and cores and coils thereon from the top of said housing, means at the other end of said housing for mounting the same on a chassis, the top of the housing being apertured for access to said condensers to adjust the same.

6. In a transformer for radio sets, an insulating block, a pair of adjustable trimming condensers on one face of said block, an insulating sleeve extending from the opposite face of said block, a pair of axially spaced cores within said sleeve, transformer coils on said sleeve and surrounding the respective cores, said condensers being shunted across the respective coils, a shield housing telescoped over said block and sleeve from the block end thereof, means including a threaded rod attached to said sleeve securing said sleeve to said block, means including said threaded rod suspending said block from the top of said housing, apertures in the top of said housing affording access to said condensers for adjusting the same, and means at the bottom of said housing for mounting the same on a chassis.

'7. The method of making a radio frequency transformer of the type including an insulating sleeve, tubular ferromagnetic cores on an insu lating rod and within the sleeve, and transformer coils surrounding the respective cores, said method comprising mounting the cores on the rod in predetermined spaced relation, inserting the assembled rod and cores into the sleeve in predetermined position longitudinally thereof, and then winding a pair of transformer coils simultaneously on said sleeve and about the respective cores.

8. The method of making a radio frequency transformer of the type including an insulating sleeve, tubular ferromagnetic cores on an insulating rod and within the sleeve, and transformer coils surrounding the respective cores, said method comprising mounting the cores on the rod in predetermined spaced relation, inserting the assembled rod and cores into the sleeve in predetermined position longitudinally thereof, and then winding a pair of identical transformer coils simultaneously on said sleeve and about the mid-portion of the respective cores.

9. In a radio frequency transformer, in combination with an insulating rod, a pair of ferromagnetic cores of tubular form mounted on and snugly fitting said rod, windings surrounding each of said cores, a single elongated sleeve of insulating material surrounding said rod and snugly fitting said cores and means for securing one end of said rod to a chassis, thereby to mount said transformer on the chassis.

10. A transformer as claimed in claim 9, wherein said mounting means comprises a shield can enclosing said transformer having an upper apertured end through which one end of said rod extends, means on the extended end of said rod to secure the same to said can to suspend said transformer therefrom, and means at the opposite end of said can for securing the same to a chassis.

11. A transformer as claimed in claim 9, wherein said mounting means comprises a block of insulating material having an opening through which one end of said rod extends, means securing said block to said rod in fixed position thereon, and a shield can enclosing said block and transformers, the end of said rod which projects through said block being secured to said can to mount said transformer and block within the same.

12. In a tuned coupling circuit for radio receivers, the combination of two members of insulating material spaced from each other and in substantially parallel relation, an element of nonconducting material supported between said members, inductively related high-frequency inductance coils supported by said element between said members, cores of magnetic material for said coils, conductor members extending between said insulating members near said coils, said conductor members being spaced from each other and from said coils in predetermined positions by said insulating members and being electrically connected respectively with the terminals of said coils, and tuning condensers carried by one of said members and having terminals electrically connected respectively with said conductor members, whereby the coils are tuned by said condensers to form coupled resonant circuits and said conductor members have fixed capacitive couplings with the coils with which they are not connected.

13. In a tuned coupled unit for radio receivers, the combination of two heads of insulating material spaced from each other and in substantially parallel relation, a supporting element of non-conducting material connecting and secured to the central portion of said heads, annular cores of magnetic material secured to said supporting element, high-frequency coils around said cores, the relation of said cores inductively coupling said coils, conductor members spaced from each other and from said coil and extending between said heads, said conductor members being substantially parallel with each other and with said supporting element and electrically connected respectively with terminals of said coils, and tuning condensers carried by one of said heads and having electrical terminals connected respectively with said conductor members connected to the coils to be tuned by said condensers to form coupled resonant circuits, whereby said conductor members have fixed capacitive coupling with the coils with which they are not connected, said condensers having connection lugs connected directly with said conductor members.

14. In a tuned coupled unit for radio receivers, the combination of two heads of insulating ma terial spaced from each other and in substantially parallel relation, a supporting element of non-conducting material connecting and secured to the central portion of said heads, annular cores of magnetic material secured to said supporting element, high-frequency coils around said cores, the relation of said cores inductively coupling said coils, conductor members spaced from each other and from said coil and extending between said heads, said conductor members being substantially parallel with each other and with said supporting element and electrically connected respectively with terminals of said coils, and tuning condensers carried by one of said heads and having electrical terminals connected respectively with said conductor members connected to the coils to be tuned by said condensers to form coupled resonant circuits, whereby said conductor members have fixed capacitive coupling with the coils with which they are not connected, said conductor members extending through the head remote from said condensers and comprising connection terminals for said tuned coupling unit.

15. In a high-frequency resonant coupling unit for radio receivers, the combination of an insulating support, inductance coils mounted in inductive relation to each other on said support, adjustable condensers having fixed relation to said support for tuning said coils, said condensers having connection terminals, conductor members connected electrically to the terminals of said coils and to the connection terminals of said condensers, and means retaining said conductor members in fixed relation to said support near said coils, thereby establishing fixed capacitive effects between said conductor members and other parts of said coupling units.

7 16. In a high-frequency resonant coupling unit for radio receivers, the combination of a supporting rod of non-magnetic material, annular magnetic cores mounted in fixed position on said rod, inductive windings around said cores, a base of insulating material secured to one end of said rod, adjustable condensers mounted on said base for tuning said windings, conductor members spaced from said windings, and means holding said conductor members sub stantially parallel with said supporting rod and with each other, said conductor members being electrically connected to the terminals of said condensers and the terminals of said windings, whereby fixed capacitive effects are established between said conductor members and the other parts of the coupling unit.

JOHN V. FILL.

Images