US2346584A - Coupling device - Google Patents

Description

April 11, 1944.

F. N. JACOB COUPLING DEVICE v Filed May 16, 1942 Patented Apr. 11, 1944 UNITED STATES PATENT OFFICE COUPLING DEVICE poration of Illinois Application May 16, 1942, Serial No. 443,321

9 Claims.

The invention pertains to an improved form of coupling device including coupled inductors provided with adjustable ferro-magnetic cores for pre-tuning purposes, so that the inductors of the device may be connected respectively in the circuits to be coupled, after which the circuits and included inductors may be pre-tuned to any desired frequency or frequencies. The coupling device of the invention is adapted for use in radio receivers generally, wherever coupled pro-tuned circuits are required, together with facilities for accurately adjusting the inductancs of the coupling device when connected in the circuits of which they are parts,'to accurately tune the circuits to a predetermined frequency-or frequencies, to compensate for'inductance and capacitance that may be included in said circuit respectively. The coupling device of the invention is particularl adapted for use as an intermediatefrequency transformer for superheterodyne receivers.

The coupling device of the invention consists essentially of two coaxially arranged inductors each including an inductance coil and a ferromagnetic core adjustable axially relatively to the coil, the coils being preferably arranged in endto-end relation and so spaced from each other as to secure the desired degree of coupling between said coils. The invention further provides a simple and inexpensive means for independ ently adjusting the inductance of the inductors from the same end of the coupling device, thereby avoiding the inconvenience in adjusting the inductors after they are mounted in a radio receiver, incident to adjusting the inductance of one of the inductors from one end of the'device and adjusting the inductance of the other inrotor from the other end of the device, as has frequently been done in the past.

Heretofore, it has been proposed to adjust the vice, provided with powdered iron cores for adlusting purposes, in a number of ways, for example, by providing a yoke or framework extending longitudinally of the coupling device for adjusting the inductor remote from the outer end of the coupling device which is readily accessible to the workman, which adjusting devices are relatively expensive to manufacture and tend to introduce undesired losses in the operation of the coupling device; second, to avoid the need for the connecting yokes-or framework referred to, it has been proposed to avoid the coaxial arrangement and dispose the inductors of the coupling device with their axes in spaced and parallel so coaxially arranged inductors of a coupling derelation, which arrangement besides resulting in a larger coupling device, also increases its cost of manufacture and introduces the possibilit of zero coupling occurring, as well as requiring for one of the adjustable inductors a long core stud presenting the possibilities of undesired operating effects in connection with the coupling device as a whole.

The difliculties experienced with earlier types of coupling devices of the kinds referred to, are entirely overcome by the construction of the invention, in which the coils of the inductors are mounted coaxially on a single supporting tube in which the cores are disposed for axia1 movement relatively to the corresponding inductance coils, the invention providing that the coreadjacent the outer or readily available end of the coupling device when in use, shall be tubular and be provided with a tubular and externally threaded adjusting stud extending through the outer terminal plate of the coupling device, to be readily accessible so that it may be turned by the workman to adjust the adjacent inductor as desired; the invention-also provides the core of the inductor remote from the outer end of the device, which may be a solid core, with a cross-slot or equivalent conformation in its end towards the outer adjustable core, as a result of which a correspondingl shaped tool of suitable material, may be inserted through the tubular adjusting stud of the outer inductor and engage the crossslot in the other core, to adjust the inductor remote from the outer end of the coupling device as desired.

,Another object of my invention, using cores of the construction described, is to so proportion the internal diameter or the tubular core to its external diameter, that its effective core to coil permeability is substantially the same as the effective core to coil permeability of the solid core:

The invention will best be understood by reference to the accompanying drawing illustrating a preferred embodiment thereof, in which:

Fig. 1 shows the coupling device of the invention in side elevation with the shield can thereof in vertical, central, sectional view,

Fig. 2 is a plan view of the coupling device shown in Fig. 1 with the shield can removed,

Fig. 3 is a vertical, sectional view through the coupling device to an enlarged scale, taken along the line 8-4 in Fig. 2,

Fig. 4 is a plan view of the coupling device with the shield can in place thereon,

Fig. 5 is a vertical, sectional view .to an en- 7 largedscale through the upper end of the shield can, taken along the line 5-5 in Fig. 4, and

Fig. 6 shows in elevation and to a scale corresponding to that of Fig. 3, an adjusting tool adapted to the purpose of adjusting the inductors @own in Fig. 3. i

Similar numerals refer to similar parts throughout the several views.

As shown in Figs. 1 and 2, the coupling device 7 case in pi form, although it will be understood. that the windings of the inductance coils may, ,have any other form as desired. Also extend-' ingbetween the plates I. and II are four-com ductive bus rods I! (Fig. 2) two of whichare shown in Fig. 1 as connected with the terminals of the windings-of the coil l5, and also connected.

with a tuning capacitor l8. The other two bus rods H. are similarly connected with the termi nals of the 'coil i6 and with a tuning capacitor [9. The inner ends of the bus rods i! are con-' ablesdjusting tool, for example of the had shown in Fig. 6, consisting of a rod M of insulating and non-magnetic material, having a diameter slightly smaller than the bore in the tube 23, and provided at one end with a iiatv extension 21a for engaging the slot 22a in the core 22, said rod 21 being provided adjacent its other end with a slender cross-rod 21b having projecting ends for entering the cross-slot 22a in the tube 23 when it is desired to adiust the core 2!.

As a result of the the coupling device has been connected in desired circuits, the coil l6 and its circuit may be pre-tuned to a desired frequency by inserting the end 21:! of the adjusting tool through the tube 23 and into engagement with the core 22,. and turning the rod 21 until the desired tuning of the circuit including the coil It is secured; similarly, by reversing the rod 21 and a in the sleeve-23 with the cross-rod 21b,

., the core 2! may be moved axially relatively to the coil I5 until the desired pre-tuning of the circuit including the said coil 15 is eiIected. It

will be observed that the construction described is simple and inexpensive to manufacture and that it permits .the coupling device to be of minimum size consistent with any contemplated use, The rods i2 and i3 although preferably metallic, by being connected with diagonally opposite corners of the plates II and II are subnected 'at the plate H, which is the mounting end of thecoupiing device, with terminal lugs 20 for circuit connection purposes. Asmore clearly shown in Fig. 3, tube ll cona first ferromagnetic'core 2| for coopera tion with the coil ii and a second ferromagnetic stantially spaced fromthe coils l5 and II so that their eflect on the operation of the inductors is so small as tobe negligible: the same is true of the bus rods H. The invention thus provides acompact and efiici'ent construction of couplinz core 22 for cooperation with the coil [6. The

core 2| is tubular and has molded into its outer or upper end, the end of an threaded tube 23 having a bore ofsubstantially the same diameter as the bore extending axially through device, and at the same time prczwide for convenient access for adjustment purposes, to either desired one of the. adjustable cores of the coupling device, through same end of the device,

thus avoiding the necessity in using the ecu-- .pling device, ofmaking any tuning adjustments the core 2|. The threads on the tube 23 engage internal threadsin' a sleeveu'which is shoul dered at its inner end to provide a centering seatfor the adjacent end or the tube It; said.

sleeve 24' extending centrally through and being rigidly secured to the plate It. As a result of the construction described, turning the tube a correspondingly moves the core 2! axially in the tube ii to change-the inductance of the coil Ii for the purpose of tuning the circuit in which the coil l5 may be included.

The core 22 is provided with a threaded stud 25 extending axially therefrom through the plate Ii, which is in threaded'engagement with a nut 25 secured to said plate, said nut being of any well known construction yieldingly engaging the threads on the stud 25 to prevent accidental turning of said stud. Said nut 28 is preferably provided with a tubular extension through the plate ii securing a disc its in centered relation on. the plate ii to form a centering seat. for the adjacent end or the tube id. The end of the stud 2d outside or the nut is provided with a slot 25a to facilitate initially assembling the stud 'in the nut it before the coupling device is connected for use, and said core is provided at s Outer pper end with a cross-slot 22a for accurately adjusting the core 22 to tune the circuit in which the coil in may be connected, by correspondingly moving the core 22 axially the'tube i6. 7

from the end of coupling device employed y to mount the device on a support or chassis. "As illustrated 1 and 4, the coupling device may conveniently be contained in a shield can 28 held in place'around the plates II and ii by nuts 29 engaging threaded extensions of the rods l2 and 83. The outer end of the shield can. is provided with an aperture 30 of substantially theexternal diameter of the tube 23,

and a shutter 8! is pivotally mounted on the inner surface of the end of the can 28, by a rivet 32 so that said shutter may be moved by a lug tietoclose or open the aperture 3! as desired. The shutterdi is preferably provided with an onset portion Mb entering the aperture lid for the closed position of the shutter, to-hold the shutter in its closed position unless it is desired .to open the aperture at which time the opening movement is permitted by the yieldhis nature of the material oi the shutter 3|. As shown in Fig. 2 a spring t3 engages at its midportion, the external suriace oi thetube 23, and esmnds at its ends into engagement with the extensions of the rods 52 and it, to hold the tube 28 and core 23 in any adjustment that may be given them.

for ens s ns a suit 35;

With the cores 2i and 22 constructed as described, and each having an external diameter or and with the tubular core 2i having an internal diameter of .2", I find that the core to coil permeability of the core 25 is substantially the cane as the core to, coil permeability of the core.

construction described, when a While I have shown my invention in the particular embodiment described, I do not limit myself thereto as I may employ equivalents thereof without departing from the scope of the appended claims.

Having thus described my invention, what I claim-is:

1. An adjustable ferromagnetic core assembly for use with high frequency alternating magnetic fields including in combination a tube of insulating material, a first ferromagnetic core having an axial aperture and mounted for axial movement in said tube and having a first screwthreaded holding connection, and a second ferromagnetic core mounted in said tube for axial movement and spaced axially from said first core and having a rod-engaging conformation accessible to an adjusting rod extended through said aperture in said first core and having a second screw-threaded holding connection, whereby said second core may be turned and adjusted.

2. An adjustable ferromagnetic core assembly for use with high frequency alternating magnetic fields including in combination a tube of insulating material, a first ferromagnetic core having an axial aperture and mounted for axial move ment in said tube and having a first screwthreaded holding connection, a second ferromagnetic core mounted in said tube for axial movement and spaced axially from said first core and having a rod-engaging conformation accessible to an adjusting rod extended through said aperture in said first core and having a second screw-threaded holding connection, whereby said second core may be turned and adjusted, and means independently restraining said cores against accidental turning.

3. An adjustable ferromagnetic core assembly for use with high frequency alternating magnetic fields including in combination a tube of insulating material, a first ferromagnetic core having an axial aperture and mounted for axial movement in said tube and having a first screwthreaded holding connection, a second ferromagnetic core mounted in said tube for axial movement and spaced axially from said first core and having a rod-engaging conformation accessible to an adjusting rod extended through said aperture in said first core and having. a second screw-threaded holding connection, whereby said 'second core may be turned and adjusted, a shield can containing said tube and said cores and having an end wall adjacent said first holding connection and apertured in line therewith, and a shutter pivotally connected with said end wall for closing said can aperture.

4. An adjustable ferromagnetic core assembly for use with high frequency alternating magnetic fields including in combination a tube of insulating material, a first ferromagnetic core having an axial aperture and mounted for axial move ment in said tube and having a first screwthreaded holding connection, and a second ferromagnetic core mounted in said tube for axial movement and spaced axially from said first core and having a rod-engaging conformation accessible to an adjusting rod extended through said aperture in said first core and having a second screw-threaded holding connection, whereby said second core may be turned and adjusted, said first screw-threaded holding connectlon including an externally threaded sleeve extending axially from said first core and having a bore for loosely receiving said adjusting rod.

5. An adjustable ferromagnetic core assembly for use with high frequency alternating magnetic 6 fields including in combination a tube of insulating material, a first ferromagnetic core having an axial aperture and mounted for axial movement in said tube. and having a first screwthreaded holding connection, and a second ferromagnetic core mounted in said tube for axial movement and spaced axially from said first core and having a rod-engaging conformation accessible to an adjusting rod extended through said aperture in said first core and having a second screw-threaded holding connection, whereby said second core may be turned and adjusted, said cores having substantially the same external diameters as each other.

6. An adjustable ferromagnetic core assembly 20 for use with high frequency alternating magnetic fields including in combination a tube of insulating material, a firstferromagnetic core having an axial aperture and mounted for axial move ment in said tube and having a first screw- 25 threaded holding connection, and a second fermmagnetlc core mounted in said tube for axial movement and spaced axially from said first core and having a rod-engaging conformation accessible to an adjusting rod extended through 3 said aperture in said first core and having a second screw-threaded holding connection, whereby said second core may be turned and adjusted, said first core having an internal diameter not substantially in excess of half of its 35 external diameter.

7. An adjustable ferromagnetic core assembly for use with high frequency alternating magnetic fields including in combination a tube of insulating material, a first ferromagnetic core having an axial aperture and mounted for anal movement in said tube and having a first screwthreaded holding connection, and a second ferromagnetic core mounted in said tube for axial movement and spaced axially from said first core and having a rod-engaging conformation accessible to an adjusting rod extended through said aperture in said first core and having a second screw-threaded ,holding connection, whereby said second core may be turned and adjusted, said cores having substantially the same external diameters as each other, and said first core having an internal diameter not sill stantially in excess of half of its external diameter.

8.4m adjustable ferromagnetic core assembly for use with high frequency alternating magnetic fields including in combination a tube of insulating material, a first ferromagnetic core having an axial aperture and mounted ior axial movement in said tube and having a first screwthreadecl holding connection, and a second ferromagnetic core mounted in said tube for axial movement and spaced axially from said first core and having a rod-engaging conformation accessible to an adjusting rod extended through said aperture in said first 'core and having a second screw-threaded holding connection, whereby said second core may be turned and adjusted, said cores having substantially the same high-frequency permeability.

9. An adjustable ferromagnetic core assembly for use with high frequency alternating magnetic 4 messes s an si aperture and mounted for asdai movemeat in said tube and having s fisst screwi ii'eeclezi holding connection, and a second imaetic core mounted in said tme for axial vement and spaced axially from said first core and having a tori-engaging conformation accessible to an adjusting rod extended through said wee in said first sore and having a second screw-threaded! holding connection whereby said second core may be turned and adjusted, said cores having substantially the same external diameters as eech other, and said first core ha aninternal diameter not substsntiaily in excess of half of its external diameter, said cores having substantially the same high-frequency permeability.

1- N. JACOB.

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