US1641925A - Inductive coupling device - Google Patents

Description

1,641,925 Sept. 6,1927. J. G GABRIEL 1 INDUCTIVE COUPLING DEVICE Original Filed -29, 1923 {J [6 4 J 4 RECEIVER T L6 9 9o" we Angular Rofafion [5 to secure this result by providin Patented Sept. 6, 1927.

UNITED STATES PATENT OFFICE.

JOHN C. GABRIEL, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

/ INDUCTIVE COUPLING DEVICE.

December 29, 1925. Serial No. 78,149.

Original application filed December 29, 1928, Serial No. 688,299. Divided and this application filed This invention relates to a coupling device and more particularly to an arrangement whereby the coupling between two circuits may be varied.

I This application is a division of the application Serial No. 683,299 for high frequency transmission, filed December 29, 1923,

' to J. C. Gabriel.

In connection with certain apparatus, for

W example, that used in radio systems, it is desirable to be able to accurately adjust the degree of coupling between associated circuits.

- In general it has heretofore been pro osed a justable coupling devices or vario coup ers comprising solenoidal coils, one of whlch 1s rotatable relatively to the other.

In this type of vario coupler the ad ustment for the entire range of coupling variation is aiiected by a 90 rotation of the rotatable coil. For equal angular ad ustments of the coil the rate of change of coupling is non-uniform throughout the range of adjustment and increases sharply near the positions of minimum and maxlmum couplin This rapid and irregular variation of the coupling constitutes a marked disadvantage, I 9 since it increases the difliculty of efiectlng an accurate adjustment of the coupling, es-

pecially at or near the minimum limit.

An object of this invention Is to permit the couplin between electrical clrcuits to be 5 varied uni ormly from maximum to minipling device throughout the range of operation.

A feature of the inventlon relates to the provision of a vario coupling having windings such that the variation of coupling is substantially a linear function of the angle of rotation of the movable element over 180 de ees.

The novel features and combmations which are believed to be characteristlc of this invention will be defined in the subjoined claims.

The invention both as to its constructlon and operation may be understood by reading the following descri tion in connection with the accompanying rawings, in which Fig. 1 shows the construction of a coupling unit or vario coupler in accordance with this invention; Fig. 2 shows diagrammatically a circuit including the coupler; and Fig. 3 illustrates curves which serve to explain the operation of this invention.

In Fig. 1 there is shown a variable inductance or vario coupler comprising two coils, 1 and 2. Each of these coils comprises a cylindrical supporting form having a slotted portion at one end upon which the conducting wire is wound to constitute a solenoidal winding and a figure 8 winding. By figure 8 type is meant the general type illustrated in the U. S. patent to Ourtis 1,367,734, February 8, 1921.

Coils 1 and 2 are 'so arranged that the slotted portions of the supporting forms, upon which the figure 8 turns are wound, face one another and are directly opposed. As herein shown coil 1 is stationary'while coil 2 is mounted on the shaft 7 carrying the knob or dial 12 by which it may be rotated. The movable coil is connected to an external circuit or apparatus by leads 8 and 9 brought out through the shaft 7. If desired these leads may be connected to flexible conductors 10 and 11.

In Fig. 2 a coupler, such as has been described above, is shown included in a radio receiving system. The stationary coil is included in the antenna circuit and the movable coil is included in the tuned receiving circuit associated with the antenna.

Fig. 3 is a graphic representation of the coupling variation obtainable with a vario coupler having solenoid windings and that which may be obtained by using the vario coupler described above. The coupling characteristic of vario couplers having solenoid coils is represented by curve B, while the characteristic of the coupler hereinbefore described is represented by the curve A.

grees. Moreover, as shown in curve 38, the rate of change of coupling is variable at all points throughout the range of adjustment of the movable coii and this variation is especially marked at or near the maximum or minimum values. in accordance curve A, the rate of change of cor uniform between maximum and .1 values.

As stated above, each coii comprises both solenoidal and figure ii windings. The numher of turns in the solenoid-e1 winding for each coil in relation to the number of turns oi the figure 8 winding is proportioned in such a manner that the mutual inductance of the two solenoidal windings is substantially equal to that of the two figure windings. When the coils consist of a few turns the number of each type will be approximately equal, the exact proportion being determined experimentally.

As coil 2 is rotated the mutual inductance between the solenoidal windings of the two coils will remain constant. The mutual inductance between the figure 8 windings, however, will be continuously variable and, beyond a certain point, the electromotive force thereby induced in coil 2 will oppose that induced by the cooperation of the solenoidal windings. When the coils are in such a position that the figure 8 windings of each coil are directly opposed, the direction of the E. M. F. induced in the figure 8 windings of coil 2 will be the same as the direction of the E. M. F. induced therein by the solenoidal windings of coil 1. Maximum coupling will occur in this position, since the E. M. F. induced in the figure 8 windings is added to the E. M. F. produced by the solenoidal winding. With the rotation of coil 2 the value of the current in the figure 8 winding decreases, until it reaches zero when the angle of rotation is 90. As coil 2 is rotated further, that half of the figure 8 winding which was initially opposed to the upper half of the figure 8 winding of coil 1 is now approaching the lower half of the figure 8 winding of coil 1. Since, due to the figure 8 construction of the windings, the direction of flow of current in the lower half of coil 1 is opposite to the direction of flow in the upper half, the E. M. F. induced in the figure 8 winding of coil 2 will be changed in direction and will consequently oppose the E. M. F. induced in the solenoidal winding of coil 2. As the angle of rotation of coil 2 is increased from 90 to 180, the opposing E. M. F. induced in the figure 8 winding increases until minimum coupling is reached, at which time the E. M. F. induced in the solenoidal winding is entirely offset by the E. M. F. induced in the figure 8 winding. In other words, at maximum couplin the effect of the mutual inductance of the gure 8 windings is equal and added menace to the mutual inductance of the solenoidal windings, while at minimum couplin the efi'ect of the mutual inductance of the figure t3 windings is equal and opposed to the mutual inductance of the solenoidal windings.

Eetween and minimum the coupling value varies by an amount which proportional to the de ree of angular rotation of the coil 2, there hy giving a chan e of coupling value which is linear over the entire adjustment range.

in view of the preceding description it will be seen that this invention provides an arrangement in which rotation of the movable element through an angle of 180 is necessary to vary the coupling over the complete range, and in which the rate of change of coupling is the same for equal angular adjustments of the movable element at. all points in its operation, whereby very fine coupling adjustments may be readily and accurately made. While applicant for the purpose of disclosing the invention has described a coupler comprisin two coils, modifications such as the use 0 additional coils will readily suggest themselves, audit is to be understood that this invention is limited only by the attached claims.

What is claimed is:

1. A coupling arrangement com rising coaxially arranged stationary an movable coils havin windings composed of a solenoid section an a figure 8 shaped section, and means for rotating said movable coil through 180 to produce a coupling variable in the same sense and substantially linearly from maximum to minimum.

2. A variable inductivedevice, comprising coils having windings composed of a solenoid section and a figure 8 shaped section.

3. A coupling device comprising a. plurality of coils electroma netically related, each coil being compose of a solenoidal winding and a figure 8 winding, and means for rotating one of said coils.

4. A coupling device comprising two coils coaxially mounted and rotatable relatively to one another, each of said coils including a solenoid winding and a figure 8 winding.

5. A coupling device including electromagnetically related coils, means for relatively rotating said coils, each of said coils comprising a cylindrical supporting form having an unslotted portion and a slotted portion, and a winding consisting of solenoidal turns and figure 8 turns wound respectively uponsaid unslotted portion and said slotted ortion.

6. A coup ing arrangement comprising a plurality of coils electromagnetically related, each of said coils comprising a. substantially cylindrical form, a portion of which is slotted to permit figure 8 turns to be wound upon it, a. winding consisting of. solenoidal turns in series with said figure 8 turns wound upon said form, and means for rotating one of said coils through 180 to vary the coupling from minimum to maximum.

7. A coupling arrangement consisting of two inductively related coils each of which is composed partly of solenoidal windings and pzrtly of figure 8 windings, said windings ing arranged to establish a constant mutual inductance between the coils, the rotation-of one of said coils controlling the electromotive force induced in the secondary coil by inducing a second elecihomotive force which over one part of the range of adjustment of the rotary coil tends to increase, and over another part of the range of adjustment of the rotary coil tends to decrease said first mentioned electromotive force at a substantially uniform rate, whereby there is produced a coupling variation which is adjustment.

8. In a variable coupling arrangement, means for varying the coupling between two circuits with a greater degree of uniformity than can be obtained by varying the relative position between two solenoids, comprising coupling coils each made up of a combination of a solenoid section and a figure 8 section of coil.

9. In a radio system, means for tuning the receiver for incoming waves comprising a coupling coil made up of a combination of a solenoid section and a figure 8 shaped section.

In witness whereof, I hereunto subscribe my name this 28th day of December A. D., 1925.

JOHN C. GABRIEL.

substantially linear over the entire range of i

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