US3060393A - Controllable inductor - Google Patents

Description

1962 c. e. SONTHEIMER CONTROLLABLE INDUCTOR Original Filed July 22, 1954 k m m RM n PM N R ETNI O V M w n I. A G W mi AB. C

United States Patent ()fiice 3,060,393 Patented Oct. 23, 1962 3,060,393 CONTRQLLABLE INDUCTOR Carl G. Sontheinrer, Riverside, Conn, assignor to Trak Electronics Company, inc, a corporation of Connecticut Original application Early 22, 1954, Ser. No. 445,146, new Patent No. 2,973,431, dated Feb. 28, 1961. Divided and this application Oct. 16, 1958, Ser. No. 771,935 6 Claims. (Cl. 336--2tl) The present invention relates to controllable inductors including magnetically saturable material and in which the effective inductance of a signal winding is controlled by varying the relative magnetic saturation of the saturable material. In particular, this invention relates to controllable inductors including adjustment mechanism for adjusting their operating characteristics. This application is a division of application Serial No. 445,146, which issued as Patent No. 2,973,431.

The various aspects and advantages of the present invention will be apparent from the following description of a controllable inductor incorporating the invention considered in conjunction with the accompanying drawings, in which:

FIGURE 1 is a perspective view of an adjustable controllable inductor embodying the present invention, the control winding being indicated diagrammatically; and

FIGURE 2 is an elevational view of the inductor of FIGURE 1.

In FIGURES 1 and 2 an embodiment of a variable inductor 240 is shown. This variable inductor 24% may be used for various inductance control applications, for example, it may be used with two other similar controllable inductors (not shown) to provide the control circuits in a radio receiver, for example, as shown in US. Patent No. 2,973,431. The controllable inductor 240 has a control winding 37a which in operation is supplied with an electrical current which is controlled so as to provide the desired inductance control action, for example, the control winding 37a may be connected in series with the corresponding control windings (not shown) of the other two similar controllable inductors, mentioned above, as will be understood. This inductor 240 includes a signal core portion 42a comprising two elongated bars of ferrite or ferromagnetic ceramic placed longitudinally adjacent one another. This ferrite material may be similar to that disclosed by Snock in US. Patents Nos. 2,452,529; 2,452,530; and 2,452,531. A generally elongated hexagonal signal winding opening is formed by trapezoidal recesses in the adjoining sides of the two bars. The signal core portion 42a carries a signal winding 4811 which is in two halves extending through the hexagonal opening and connected in series, so that their magnetic fields are in aiding relationship around the opening to induce flux flowing around this opening. Core 42a is bridged across between a pair of copper shimes Gila resting against the side legs 2421 and 242-2 of a control core portion 52a. The control winding 37a is wound on the back part of the core 52a. The core 52a is made of a flexible magnetizable material, for example a strap of soft iron bent into a U shape to form the two side legs 242 and 243, with the ends of the side legs being bent over again toward one another in a spaced overlapping relationship to form a magnetic path for the control flux between legs 242 and 243 in shunt with the path through the core 42a. An adjustment of the effective reluctance of this shunt path is provided by a large-headed machine screw 244 of non-magnetic material threaded through a hole in the outer end of the leg 242 and resting against the inner end of the leg 243. By tightening it, this shunt reluctance is increased, so that for any given value of the current in the control winding 37a the degree of magnetic saturation of the signal core portion 42a is increased lowering the effective inductance of the winding 48a thereon. In overall effect tightening the screw 244 is equivalent to adding some turns in the winding 37a.

When the three inductors similar to inductor 240 have their control windings connected in series there may be deviations of the controlled inductance values in the respective circuits being controlled thereby, so that due to individual differences they do not track properly. The shunt control flux path adjustment by the screw 244 enables compensations to be made for the individual deviations so that the inductance values are caused to track one another.

Another adjustment for tracking characteristics is provided by changing the reluctance in series with the control flux path through the core 42a with a non-magnetic machine screw 248 which serves to skew the right shim 60a to change the effective length of the reluctance region between the right end of the core 42a and the leg 243. To facilitate the tilting .of this shim, the end of the screw may be rounded to fit it into a socket in the shim. By adjusting the screws 244 and 248 all of the controllable inductors 244i used can be adjusted to track one another as desired.

Among the advantages of using separate controllable inductors instead of having them ganged upon a single control yoke is that each of them may then be located closely adjacent the portion of the receiver circuit desired, thus advantageously enabling the use of shorter interconnecting wires within the receiver.

The advantage of such arrangements will be understood both from the standpoint of convenience and utility as well as from the standpoint of ease of service and maintenance.

From the foregoing description it will be understood that the present invention provides an adjustable controllable inductor having many advantages as discussed above, and it is understood that the apparatus described can be adapted to a wide variety of different applications and that various changes or modifications may be made therein, each as may be best suited to the particular application desired and that the scope of the present invention is intended to include such modifications or adaptations, as defined by the following claims limited only by the prior art.

What is claimed is:

l. A controllable inductor comprising a U-shaped yoke of magnetically permeable material having two legs with a back portion therebetween, a magnetically saturable core portion bridged across from one leg of said yoke to the other leg, said magnetically saturable core portion having an opening therein, a pair of adjustable permeable elements spaced from each other and extending from the ends of the two legs of said yoke toward each other, a control winding on the back of said yoke, a signal winding on said magnetically saturable core portion, said signal winding being divided into two halves connected in series aiding relationship, each of said halves passing through said opening and around opposite sides of said magnetically saturable core portion, first adjustment means for regulating the spacing between said elements, and second adjustment means for changing the spacing between one of said legs and the magnetically saturable core portion.

2. A controllable inductor comprising a length of magnetically permeable material bent into a substantially closed loop with its ends closely spaced, a control winding on said loop at a position remote from said ends, a magnetically saturable core portion extending across said loop between regions on said loop spaced from said ends,

said magnetically saturable core portion having an elongated opening therein, a signal winding on said magnetically saturable core portion, said signal winding including two connected parts, each part passing through said elongated opening and surrounding the respective areas of said magnetically saturable core portion on opposite sides of said opening, a first adjustment screw of nonmagnetic material extending between said ends for adjusting their spacing, and a second adjustment screw for changing the spacing between one of said regions on said loop and said magnetically saturable core portion.

3. A controllable inductor comprising a flexible C- shaped control yoke of magnetically permeable material having a pair of end portions in closely adjacent relationship, a control winding on said yoke, a signal core portion of magnetically saturable material having two ends, one of said ends being adjacent to one side of said C-shaped control yoke with the other end being adjacent to the other side of said C-shaped control yoke and said signal core portion being bridged across from said one side of the C-shaped yoke to the other, said signal core portion having an opening therein, a signal winding on said signal core portion, said signal winding including two winding parts each passing through said opening and around opposite edges of said signal core portion, said two winding parts being connected in series aiding relationship with respect to magnetic flux in said signal core portion and surrounding said opening, and adjustment means for adjusting the spacing between the end portions of said yoke.

4. A controllable inductor comprising a flexible control yoke of magnetically permeable material having a pair of end portions in overlapping adjacent relationship, a control Winding on said yoke, a signal core portion of magnetically saturable material having two ends, one of said ends being adjacent to one side of said control yoke with the other end being adjacent to the other side of said control yoke with the body of said signal core portion being bridged across from said one side of the yoke to the other, said signal core portion having an opening therein, a signal winding on said signal core portion, said signal winding including two winding parts each passing through said opening and around opposite edges of said signal core portion, said two winding parts being connected in series aiding relationship with respect to magnetic flux in said signal core portion and surrounding said opening, and adjustment means for adjusting the spacing between the overlapping end portions of said yoke by deflecting the end portions of said control yoke apart.

5. A controllable inductor comprising a control yoke of magnetically permeable material, a control winding on said yoke, a signal core portion of magnetically saturable material having two ends, one of said ends being adjacent to one area of said control yoke with the other end being adjacent to another area of said control yoke with said signal core portion extending between said areas of the yoke, said signal core portion having an opening therein, a signal Winding on said signal core portion, said signal winding including two winding parts each passing through said opening and around opposite edges of said signal core portion, said two winding parts being connected in series aiding relationship with respect to magnetic flux in said signal core portion and surrounding said opening, a non-magnetic spacing element between one end of said signal core portion and the adjacent area of the control yoke, and an adjusting mechanism for skewing said spacing element, thereby to change the effective length of the reluctance region between said end or" the signal core portion and the control yoke.

6. A controllable inductor as claimed in claim 5 and wherein said adjusting mechanism is an adjusting screw which tilts said nonmagnetic spacing element.

References Cited in the file of this patent UNITED STATES PATENTS 349,611 Stanley Sept. 21, 1886 2,462,423 Polydoroff Feb. 22, 1949 2,488,393 Geiselman Nov. 15, 1949 2,581,202 Post .Tan. 1, 1952 2,771,587 Henderson Nov. 20, 1956 FOREIGN PATENTS 1,011,769 France Apr. 9, 1952

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