US2946029A

US2946029A - Impedance assembly

Info

Publication number: US2946029A
Application number: US554872A
Authority: US
Inventors: Abrams Ralph; Jr Danforth W Comins; William A Melanson
Original assignee: Cambridge Thermionic Corp
Current assignee: Cambridge Thermionic Corp
Priority date: 1955-12-22
Filing date: 1955-12-22
Publication date: 1960-07-19
Anticipated expiration: 1977-07-19

Description

July 1'9, 1960 R. ABRAMS ET AL IMPEDANCE ASSEMBLY Filed Dec. 22, 1955 L.. im m.; W w mma d n am n I www y Bbw f nited States Patent O IMPEDANCE ASSEMBLY Ralph A'brams, Sharon, Danforth W. Comins, Jr., Con` Filed Dec. 22, 195s, ser. No. 554,872

s claims. (c1. 336-136) The present invention relates to tunable impedance devices of the type having an adjustable core member.

`Objects of the invention are to provide adjustable impedance devices, such as for example coil forms, that are especially suitable for miniature or near miniature embodiments, to provide such devices that are shock resistant, exceptionally rugged and precise, and yet comparatively inexpensive, to provide such devices which are electrically shielded against radiation and therefore especially suitable for use in close proximity of other elements in circuits where adjacent mounting is necessary, to provide such devices which give awide variety of possibilities of mounting -as well as modification of electric characteristics such as type of windings or electrodes, or number ofl terminals, and to provide devices of this type which permit partial assembly at the factory and easy and secure com pletion and mounting with basic tools.

A brief summary of the invention, yindicating its nature and substance for attaining the above objects, is as follows. A tunable impedance device according to a principal aspect of the `invention comprises tubular form means such as a coil form, housing means which have at one end stud means with mounting means on the outside of a cavity that lits the form means and which housing means has at the other end shell means forming a chamber that is wider than the -form means, the form means extend-ing from the cavity into the shell means with clearance to accommodate an impedance element such as -a coil and stationary cup core members, and means axially penetrating the stud means into the space within the form means, for carrying an internal core member and for axially adjusting it within the form means. In a preferred embodiment, the shell contains cup core members surrounding a coil on the form means and elastic spacing members within the shell which are compressed by a terminal board that is yfixed to the open end of the shell with a spring ring or a cap, which ylatte-r can be provided with a ground tab.

. These and other objects, and aspects of the nature of the invention will appear from the herein presented description of several typical embodiments illustrating its novel characteristics.

The description refers to a `drawing in which Fig l is the top elevation of an assembly according to the present invention with part of the spring ring broken away to show the terminal board key rin Iits shell notch;

Fig. 2 is a section on lines -2-2 of Fig. l;

Fig. 3 is a section on lines 3-3 of Fig. 2;

Fig. 4 is a section lon lines -4--4 of Fig. 2;

Fig. 5 is a top elevation of the spacer that can be incorporated in the assembly;

` Fig. 6 is a top elevation of the cup core cap incorporated in the assembly;

Fig. 7 is an axial section through the retaining cap of a second embodiment of the invention; and

Fig.,8 is an axial section similar to Fig. 2, of a second embodiment of the invention.

In Figs. 1 to 4, the housing 21 has a shell portion 21.1 and a stud portion 21.2. The shell portion has, in the embodiment shown, an annular recess 21.11 for the retaining spring ring to be described below, and a notch 21.24 for the key 32.7 of the terminal assembly to be described below. The stud portion 21.2 has a cylindrical portion 21.21, threaded on the outside, and a hemispherical portion 21.22which latter is provided /with a plurality, for example four slits 21.23. The hemispherical portion 21.22 of the stud portion 21.2 of the housing 21 has an axial perforation 21.3 with an inside thread to receive vthe spindle 25 of the tuning core.

The chamber of the shell portion 21.1 leads into the `cavity of the stud portion by way of a shoulder 21.9.

A form 23, made of insulating material, fits the cavity 21.4 of the stud portion 21.2. Within the form 2.3l is slidably inserted a tuning core or slug 24 which is mounted on the above mentioned spindle 25 that is threaded into the axial hole 21.3 of the hemispherical portion 21.22 of the stud portion 21.2 of the housing.

In the present embodiment which represents a tuning reactance, the core is made of iron powder and has a slot 24.1 for screwing it onto the spindle 25 by means of an inside threaded recess 24.2.

On the form 23 is wound a wire winding 27, indicated by cross-hatching in Figs. 2 and 3. The winding is surrounded by a cup core 28 and a cup core cap 29, both made of iron powder material. As indicated in Fig. 2, the cup core cap has a recess 29.1 and a number, such as four, notches 29.5, as indicated in Fig. 6. On the cup core cap tits a spacer 31 of elastic material such as sponge rubber which is also shown in Fig. 5 and which has a number, for example four, notches 3.1.1. Between the bottom of the cup core 28 and the shoulder 21.8 is a rubber washer 21.9.

On the spacer 31 lits the terminal board assembly 32 which, as shown in Fig. l, has ya number, for example four, terminals 32.1. 'These terminals are hollow as indicated at 32.5, permitting a wire to be threaded therethrough and soldered thereto from the outside thereof.

A retaining spring ring 35 i-s inserted in the recess 21.11 in conventional manner, as indicated in Figs. il and 2.

In this embodiment of the invention, the spindle 2S with slug 24 is lixed relatively to the housing 21 by means of a lock nut 25.1'which serves for tightening the hemispherical portion 21.22 on the spindle 25, by means of the slits 21.23 which reach somewhat into the threaded portion of the spindle region 21.2, the lip 25.2 of the lock' nut 25.1 serving to compress the slotted hemispherical .portion 21.22 when the lock nut is tightened. 'Ihe core- 24 is adjusted by means of rotating the slotted spindle 25. with a simple tool. position by means of tightening the lock nut \25.11 as above described.

The assembly can be mounted on a support such as a panel indicated at l41 of Fig. 2.,.by means of a lock washer' `42 and a nut 43, likewise shown in Fig. 2.

The housing 21 is conveniently made from brass, the coil form 23 from phenolic resin, the spacers `21.9 and 31 from sponge rubber and the terminal board 32 for exam- The above described device is assembled and operated as follows.

These assemblies are usually shipped from the factor with the tuning core 24 on the spindle 25 assembled with-V in the housing 21, whereas the parts that go into the,

shell portion 21.1 are furnished in bulk.

After adjustment, the core is set inl Before completely assembling the device, the impedl the lower end ofthe form restingv at thel conical bottom of the cavity with the washer 21.9. inserted in theA shellV ont the shoulder 21.8, as indicated in Fig. 2. The upper endy ofthe form extends into the chamber of the shell. portion 21.1. The cup core can then be filled with irnpregnant as required' according to conventionwtech.- niques;

If it is desired to. pot the coil assembly outside ofthe shell, for example for the purpose of baking it to properly cure the impregnant, various expedients are feasible, for example the` following' one. The coil form with the winding on iti is inserted into the powder metal cup core by means ofI a jig which has a plurality of raised. portions corresponding in shape to that of the cup core cap 29, thus properly positioning the form within the cup. By means of an eye dropper, some adhesive agent such yas available under the trade designation Epoxy is then applied to the gap between the cup core and the form, andv permitted to cure. These Epoxy materials, well known at this time, are resin polymers that together with a curing agent such as a catalyst or cross-linking agent set at room temperature within abouty one hour, and completely lill a gap due to their surface tension properties. The subassembly of form and cup can then be handled in any desirable fashion, and since the gap therebetween is sealed, the impregnant is with safety confined in the void between the. coil and cup core during filling as well as baking.

Care has to be taken in all cases not to allow any of: the impregnating compound to become deposited on the inside of the form since this would impair movement of the tuning core. This however is effectively prevented by the above described sealing technique or one similar thereto.

No matter how the shell, the coil. form andY the cup core are assembled the cup core cap 29 is then put on and then the sponge rubber spacer 31, care being taken to orient the coil leads to pass through the notches of 29 and 31 (Figs. 5 and 6) and to mate them correctly with the terminals whenthe terminal assembly 35 is nally put.

on. The core leads are left extending through the cup corey notches at least one inch; for easy insertion through the terminals. They are then stripped and tinned to within about one-eighth of an inch of, the cup core.

The coil leads are threadedv through' the terminals of the terminal board, through the holes 32.5 indicated in Figs. 1 and 2 and the terminal board is then placed over the spacer 31. The terminal board is pressed down to compress the spacers, and the retaining ring 35 is inserted into the groove 21.11. The bent ends protrude, as shown in Fig. 1, through the housing notch 21.24 which also accommodates the key 32.7 of the terminal board.

The leads can then be soldered to the terminals in conventional manner or otherwise connected.

It will be evident that the terminal assembly can be furnished with any desired number of terminals, four being shown in the present embodiment.

The embodiment according to Figs. 7 and 8 is in principle similar to that abovedescribed, with the following modications.

^ Instead off holding the assembly together by means of a spring ring such as component 35 of Figs. 1 and 2, a cap. 51 with slots 51.1 is sometimes preferable. This cap is slightly collapsed after slotting so that it fits snugly on the shell outside diameter. For permanent assembly the cover can be secured to the shellwith a dot of solder indicated at 52 of'Fig. 8. This construction has the advantage that the assembly can be provisionally secured without the use of any tool whatsoever and can then be permanently fixedA without any danger of a` confining member such as spring 35 becoming detached.

Fig. 8 also indicates a somewhat different embodiment of the form 53, which has in this instance flanges 53.1, 53.2 for better confining a winding, for example of very fine wire. In this instance the cup core cap 59 can be flat on both sides.

Fig. 8 also indicates another mode of fixing the adjustabler core. member 2`4 with` its spindle 25, by means of` a torsion spring ring member 62 on a neck portion 27 of thestudy portion 61.2 of'v the housing 61 with its shell portion 612.1, In this instance the outside thread ofthe stud end 61.2Y is-,sornewhat wider than the spring ring 62, so that a mounting washer 42 and a nut 43 can be inserted over the end ofy the stud portion with the spindle 25 protruding therefrom.

This embodiment lends itself especially well for providing a grounding terminalA for the assembly` as a whole. Forthis` purpose a tab 65 is` stamped from the metal for the cap 51 and bent upwardly as indicated in Fig. 8-.

It will now be evident that the above described construction provides a firm and positive support for the form 23, in the cavity 21.4 and at the same time permits complete withdrawal of the core 24 from the

cup core

28, 29 thus permitting a wider range of adjustment. It will be further apparent that the stud portion 21.2 not only provides the above mentioned cavity forv better securing the form and for fully withdrawing the adjustable core but also has the function of a mounting member by way of' its outside thread 21.21. This construction thus provides unusually versatile and yet compact and simple construction, due to this triple function of the stud portion 21.2 of the housing-21.

It will be also apparent that the unobstructed outsideof the chamber portion of the housing shell 21.1 permits the use of a spring ring such as 35 of Figs. 1 and 2 alternatively with that of a slotted cap as shown in Figs. 7 and 8, since it is possible to use a housing according to Figs. l and 2, provided with the annular recess 21.11, also with a cap 51, according to requirements.

It will be further apparent that the assembly according to the present invention is unusually well shielded electrically and is particularly well suited for applications that require miniature size, a rugged and shock resistant construction' and a mechanically enclosed and thus fully' protected coil.

' The construction according to Fig. 8, with a cap 51 having a grounding tab 65, lends itself especially well" for mounting on a printed circuit panel such as indicated at 40 ofy Pig. 8. In this instance the terminals 32 and the tab 65 are inserted into perforations of the panel 40 and the protruding ends dip soldered thereto in conventional manner. It will be evident that the stud mounting means such as the outside thread of the stud portion, for the washer 42 and the nut 43, can then be omitted.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

We claim:

l. A tunable impedance ydevice of the type having an adjustable core member, comprising: smoothly tubular form means; a housing which has at one end stud means with fastening means on the outside and with a `cavityl that lits said form means, and' which housing has at the other end integrally therewith a chamber that is wider than said form means, said cavity being contracted at the extreme end of the stud means and communicating on the opposite end with said chamber with a shoulder, said form` means extending from said cavity into said chamber; in said chamber a cup-shaped `core with its' bottom resting on said shoulder and having in said bottom an opening for said. form means, the clearance between said core and Said form means accommodating a Winding; a disk-shaped core cap fitting into the open end of said cup-shaped core and resting on said form means; loosely inserted into said chamber elastic washer means extending over both core and core gap; means including a terminal board secured to the outer end of said chamber for compressing and confining said core, core cap, and washer means; and axially threaded into said extreme end of said stud means and penetrating into the space within said form means, a spindle for carrying said core member and for axially adjusting it Within said form means; whereby said core means can be substantially fully withdrawn from the chamber region of said form means into its stud cavity region, such as essentially to disassociate said core means from said chamber.

2. A tunable impedance device of the type having an adjustable core member, comprising: tubular form means; a metal housing which has at one end'a stud portion with mounting means on the outside and with a cavity snugly tting said form means along a portion long enough substantially to receive said core member and' which housing has at the other end a shell portion integral therewith with a chamber that is wider than said form means, said cavity being contracted at the extreme end of the stud portion and leading on the opposite end of the stud portion with a shoulder into said chamber, and

said form means extending from said cavity into said chamber where it has a peripheral clearance to accommodate an impedance element; within said chamber a cup shaped iron core member placed with its bottom resting on said shoulder; a' terminal board' member tting the inside of said chamber; resilient plate means arranged adjacent to said cup core member; means for holding said cup core member, said terminal board member and said resilient plate means under compression Within said chamber; and, attached at said contracted extreme end of said stud means and extending into the space within said form means, means for carrying said core member and for axially adjusting it within said form means; whereby the core means can be substantially fully withdrawn from the shell chamber region of the form means into its stud cavity region, such as essentially to disassociate the core means from the chamber, and the form means, cup core member, plate means and terminal board member are iirmly and compactly confined within the chamber.

3. Device according to claim 2 wherein said holding means includes an annular recess on the inside of said chamber near the outer rim of the shell portion, and a spring ring inserted therein.

References Cited in the iile of this patent 'UNITED STATES PATENTS Re. 22,103 Harvey May 26, 1942 2,130,815 Riepka Sept. 20, 1938 2,482,902 Clark Sept. 27, 1949 2,669,700 Rauch Feb. 16, 1954 FOREIGN PATENTS 479,880 Great Britain Feb. 14, 1938