US3400352A - Encapsulated inductor with external adjustable means for selectively varying the inductance - Google Patents

Description

Sept. 3, 1968 G. w. HENKE 3,400,352 ENCAPSULATED IND UCTOR WITH EXTERNAL ADJUSTABLE MEANS FOR SELECTIVELY VARYING THE INDUCTANCE Original Filed Jan. 2, 1962 J /a /3 l4 F IG 2 FIG FIG 3 FIG. 4

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United States Patent ENCAPSULATED INDUCTOR WITH EXTERNAL ADJUSTABLE MEANS FOR SELECTIVELY VARY- ING THE INDUCTANCE Gustave W. Henke, Freeport, N.Y., assignor, by mesne assignments, to Varian Associates, Palo Alto, Calif., a corporation of California Original application Jan. 2, 1962, Ser. No. 163,936, now Patent No. 3,239,782. Divided and this application Mar. 7, 1966, Ser. No. 558,154

4 Claims. (Cl. 336-75) ABSTRACT OF THE DISCLOSURE There is disclosed encapsulated variable inductors provided with externally adjustable means in the form of a coaxial ring or nut adapted to be moved along the length of the inductor for adjusting the inductance. The ring is provided with a resilient inner portion which engages the encapsulated inductor to maintain the adjusted inductance.

This is a division of application Ser. No. 163,936, filed Jan. 2, 1962, now Patent No, 3,239,782.

This invention relates to continuously variable inductors and more specifically to those of miniature type which might also be encapsulated to exclude the effects of moisture and other effects.

One of the objects of the invention is to provide exact adjustment of inductance with minimum cost in construction and assembly.

A specific object of the invention is to improve over the prior methods of varying an inductance; these prior methods consist mainly of the insertion of a ferrous or non-ferrous metallic slug inside the windings of an inductance.

Another object of the invention is to provide a solenoid inductor of cylindrical external shape or any shape allowing for the placement of a screw thread coaxially with the winding of the inductance. A metallic nut or sleeve screwed over these threads will cause the inductance to decrease as the position of the nut moves to the center of the coil.

These and other objects of the invention will be more fully apparent from the drawings enclosed herewith in which FIG. 1, shows a miniature type of variable inductor.

FIG. 2 represents a corresponding circuit diagram.

FIGS. 3 and 4 show a modification of this embodiment in a more simple form not requiring the use of a screw thread.

FIG. 5 illustrates another modification of the invention involving a thread on insulating material.

FIG. 6 represents variable inductor embodying the invention in the form of an auto-transformer.

FIG. 7 represents a corresponding circuit diagram.

FIG. 8 shows two inductors in accordance with the invention adjustable simultaneously.

FIG. 9 shows a variable inductor adjustable by means of a special tool which is illustrated in a side view shown in FIG. 10.

FIG. 11 shows the invention as applied to a radio frequency transformer.

FIG. 12 shows an adjustable miniature inductance in accordance with the invention permitting fixation of the adjustment.

FIG. 13 shows a modification of the embodiment shown in FIG. 12.

FIG. 14 shows a variable inductance in accordance with the invention in the form of a double tuned circuit, and FIG. 15 shows the corresponding circuit diagram.

3,400,352 Patented Sept. 3, 1968 In FIG. 1 a plastic or other insulating capsule 1 containing a coil not shown is provided at least at a portion thereof with a thread schematically indicated at 2 over which metal nut or ring 3 is adjustable to permit adjustment of the inductance in accordance with the equivalent circuit diagram of coil 4, shown in FIG. 2.

The actual size of such a miniature type variable ind-uctance can be of the order of less than an inch, its length for example being half an inch and its outer diameter /s of an inch, while the metal ring 3 has an outer diameter of A of an inch. The terminal leads are indicated at 5, 6, respectively.

The modification of FIG. 3 shows in schematical form a coil capsule or cylinder 7 having axial end leads 8, 9 extending therefrom. Movable along the outside of cylinder 7 is a shorted turn of wire schematically indicated at 10, permitting the inductance of the coil enclosed in 7 to be changed in a continuous movement.

As apparent from FIG. 3 shorting wire 10 is also connected to axial lead 8 by means of a wire 11 permitting to the adjustment of the inductor to be held at a fixed value, if desired.

FIG. 4 shows a metallic ring 12 with diagonal clips 13, 14, and arranged to be movable over the outer surface of capsule 15. In this way, threads on the capsule are not required.

According to FIG. 5, the inductor capsule 16 is provided with a sleeve of insulating material 17 which is arranged with push-fit over capsule 16, and which has an outer thread permitting adjustment of metal nut 18 over sleeve 17.

In the embodiment of FIG. 6, the inductor capsule 19 is provided with two axial end leads 20, 21 and a center tap lead 22 permitting it to act as an auto transformer with variable tap.

Adjustment of inductance is elfected by nuts 23, 24 adjustable over corresponding threads, or thread portions of capsule 19.

The equipment circuit diagram is indicated in FIG. 7.

FIG. '8 shows two inductor capsules 25, 25 arranged in parallel and provided with adjustment rings 27, 28 movable over outer threads under control over a common gear element schematically indicated at 29 and meshing with outer gears formed on nuts 27 and 28, respectively.

FIG. 9 shows the adjustment element or ring 30 movable over thread 31 of an inductor capsule under control of grooves 32 peripherally provided on the outside of nut 30. In the side elevation of FIG. 10, an adjusting tool 33 is indicated which has projections fitting into grooves 32 or nut 30 and permitting adjustment of inductance.

FIG. 11 illustrates the invention in the form of a radio frequency transformer.

The coil in the capsule of FIG. 11 consists of two separate winding-s, primary and secondary, indicated at 35, 36, respectively with corresponding terminal leads projecting at one end at 37, 38, 39, 40, respectively.

Adjustment nut 41 is movable over thread 42 to adjust or trim the inductance. If desired, windings 35, 36 may be provided instead of inside capsule 34, outside thereof, and of proper diameter and pitch to form a thread for direct application of adjustment nuts.

FIG. 12 shows an adjustment nut consisting of an inner core of insulating material schematically indicated at 43 which is pressed into a metallic outer ring or sleeve of metal schematically indicated at 44. The soft inner ring 43 is threaded over the thread provided on inductance capsule 45 to permit the soft material to hold adjustment.

In the arrangement of FIG. 13 metal nut or nuts schematically indicated at 46 are used to adjust the inductance capsule 47.

A nut of flexible material 48 may be used to hold metal nut 46 in adjustment.

Nut 48, may also be of metal to act as a lock nut, but it should be noted that additional metal nut or nuts decrease the inductance value.

It should also be noted that all rings, sleeves or nuts which are used for adjustment with respect to the inductor capsule may be covered with insulating material to prevent possible electrical contact and short circuit with other components or wiring.

FIG. 14 shows a variable inductor in the form of a double tuned circuit as illustrated in the equivalent circuit diagram of FIG. 15.

In this case, the inductor capsule schematically indicated at 49 contains three windings or coils schematically indicated at 50, 51 and 52 and extending into end leads or terminals 53, 54 and 55, respectively.

Capsule 49 is provided with an external screw thread 56 on which they arranged three nuts adjustable in accordance with the invention and schematically indicated at 57, 58, 59.

The invention is not limited to the particular shape of the inductor capsule nor to the arrangement and number of windings or coils shown and described nor to the particular circuit configuration and adjustment means which have been illustrated but may be applied in any form or manner whatsoever without departing from the scope of this disclosure.

I claim:

1. An inductor comprising a substantially cylindrical encapsulating means having opposite closed ends, at least one winding located in and extending axially of said encapsulating means, said winding having terminal leads projecting through at least one of said closed ends of said encapsulating means, and at least one ring means circumferentially surrounding said encapsulating means and said winding therein and being axially movable along said encapsulating means between said ends thereof, said ring means comprising metallic material for adjusting the inductance of the winding as the ring means translates axially of said winding, wherein said ring means is provided with gripping means flexibly holding said ring means against said encapsulation.

2. The inductor of claim 1 wherein said ring means comprises an outer metal ring portion and an inner ring portion, said gripping means comprising said inner ring portion, said inner ring portion being of resilient material engaging said capsule for holding adjustment.

3. The inductor of claim 2 wherein said inner ring consists of insulating material.

4. The inductor of claim 1 wherein said ring means comprises an outer metal ring portion and an inner ring portion, said gripping means comprising said inner ring portion, for holding adjustment.

References Cited UNITED STATES PATENTS 7/1956 Ashby et al. 336l36 XR 5/1959 Fleming 336-96

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