US2664487A - Electrical resistor - Google Patents

Description

H. C. GORDEN ELECTRICAL RESISTOR Dec. 29, 1953 2 Sheets-Sheet 1 Filed Jan. 7, 1952 Enry a arden;

Dec. 29, 1953 H, c, GQRDEN 2,664,487

ELECTRICAL RESISTOR Filed Jan. 7, 1952 2 Sheets-Sheet 2 16 4 i if .18 x 15 50 I 26 28 am J1 26' Bill/4:25:25 :EsiiiW/l/IJ; 51 W .51

\\\\\\\\\\\\\\\\\\\\\\ &\\\\\\9 l 214972237 6. Garden Patented Dec. 29, 1953 UNITED STATES PATENT OFFICE ELECTRICAL RESISTOR Henry G. Gordon, Los Angeles, Calif., assignor to Gorman Manufacturing Corporation, Los Angeles, Calif., a corporation of California Application January 7, 1952, Serial No. 265,249

9 Claims. 1

This invention relates to an electrical resistance device for determining the amount of current flowing in a circuit for any given voltage applied to the circuit and has as its primary object the provision of a precision resistor of the type embodying an electrically conductive coil wound on a spool and encased in a housing which spool and housin are formed of an electrically insulating material; the invention residing in a construction and arrangement of parts and in a mode of assemblage whereby the device may be readily and economically manufactured and whereby a resistor will be produced that is characterized by its compactness and lightness and its affordin a maximum amount of performance with the smallest amount of weight and size, by its capability of withstanding great thermal change from hot to cold and vice versa, and by its immunity to the deteriorating eiiects of long exposure to adverse climatic conditions.

Another object is to provide a construction in the resistor which is particularly applicable to and facilitates the production of resistors of extremely small caliber particularly suitable for use in electronic systems such as sets used in radio and radar and television equipment and the like. Another object is to provide a construction for facilitating the positioning of a resistance coil on a spool together with laterally extending rigid terminals at the ends of the coil, arranging the assembly within a cylindrical shell and eflfectively sealing the coil within the shell.

Another object is to provide a wire-wound precision resistor of the above character which when constructed of extremely small or minute size will be quite strong and accordingly not subject to easy breakage and damage as is the case with the fragile small resistors now generally on the market, and which with the characteristics above set forth is rendered especially applicable for use in aircraft, air-borne missiles and equipment calling for maximum resistor performance under extreme variations in altitude ranging up to tremendous heights, as well as extreme variations in temperature as for example from minus 70 centigrade to plus 200 centigrade, and where extreme lightness in weight and small dimension is a desideratum.

A further object is to provide a construction in a resistor of the type specified whereby the terminals of the resistor coil may be either from the side or from the ends of the device according to requirements and to facilitate application of the resistor in a particular piece of equipment.

With the foregoing objects in view together with such other objects and advantages as may subsequently appear, the invention resides in the parts and in the combination, construction and arrangement of parts hereinafter described and. claimed, and illustrated by way of example in the accompanying drawing in which:

Fig. 1 is a perspective view of a preferential form of the resistor;

Fig. 2 is a view in longitudinal section and partly in elevation of the resistor shown in Fig. 1;

Fig. 3 is a perspective view of the resistor spool and coil assembly as removed from its housing or shell;

Fig. is a view in longitudinal section of the r assembly shown in Fig. 3;

Fig. 5 is a perspective view with portions broken away of a shell for receiving the assembly shown in Figs. 3 and 4 for encompassing and housing the resistor coil;

Fig. 6 is a view in section and elevation illustrating the manner of assembling the coil assembly in Figs. 3 and 4 within the shell depicted in Fig. 5;

Fig. 7 is a view illustrating the parts of the spool and coil assembly as separated;

Fig. 8 is a view in longitudinal section illustrating a modified form of the spool and coil assembly;

Fig. 9 is a view in vertical section showing another form of the invention;

Fig. 10 is a view in side elevation depicting a further form of the invention;

Fig. 11 is a view in horizontal section taken on the line llll of Fig. 10, with the coil removed; and

Fig. 12 is a view in vertical section and elevation taken on the line lE-l 2 of Fig. 11.

Referring to the drawing more specifically A indicates a cylindrical shell which is open at least at one of its ends and is provided at an end thereof with a wall H having an axial circular opening it which wall may be formed integral with the shell A as shown in Figs. 1, 2, 5, and 6 or may be formed independent of the shell and subsequently applied thereto to close one end thereof as shown in Figs. 9, 10 and 11.

In the construction shown in Figs. 1, 2, 5, 6 and 10 the cylindrical shell A is formed with a slot l2 adjacent its forward or open end and with a slot I l adjacent its other end closed by the wall I0.

The shell A is designed to receive a spool and coil assembly B particularly shown in Figs. 3 and 4 which assembly embodies a tubular cylindrical core 15 and which core is insertable in the open 3 end of the shell A with the inner free end portion thereof inserted in the opening I I and snugly engaged with the portion of the end wall I surrounding said opening as shown in Figs. 2, 9 and 11.

An annular flange i6 is formed on the outer end of the cylindrical core I5, the marginal portion of which is formed to abut the outer open end of the shell A and being formed with a reduced inner marginal portion I? dimensioned to snugly abut the inner peripherial portion of the shell A adjacent the outer end thereof.

The shell A with its end wall lcll andalso the spool comprising the core with its'end "flange I6, are formed of suitable insulating materfial such for example as a plastic compositionicoinposed of a phenolic thermo-setting compound, a cellulose product, a phenol resin product, nylon, pressed fibers, rubber and the like; being preferably molded of a non-hygroscopic ,heat resistant compound, with high dielectric strength and very low co-efiicient of expansion and highly resistantto thermal shock; the compound most suitably employed being onethat can withstand .over 200 centigrade and at least 1ninus 70 centigrade.

A resistance coil composed of a suitable Wire formed of an electrical conductive material of suitable resistance quality such as nichrome wire,

:is wound into a cylindrical coil C comprising a requisite number of convolutions imposed on the core l5. This coil C may either be wound digrectly on the core I 5 or may be wound on a suitable arbor and thereafter telescoped on the core. lhe terminals a--b of the wire forming cylindrical coil C may be threaded throughopenings l8 and I9 in the core I5 as shown in Fig. 8, or may be directed through the slots I2 and M in the shell A when, assembling "the element B therein, but the present invention contemplates the employment of a more substantial construction, which in the construction shown in'Figs.

l to Tinclusive consists in providing the device with a pair of rigidelectr'ically conductive terminalposts which project through the ,slots ;I2- -I4; the post D being forinedon the margin of an annulus encircling the core I5 .ibetween tlie fiange it and the adjacent end of the coil C to which-one end a of the wire forming the coil C isatlixed in suitable fa hion, preferably by welding. The post E is formed on the margin of 1 an annulus 2i encircling theinner end portion of the core I5 and to which the other terminal b of the wire forming coil C is affiXed as by welding. In connecting the ends ab of the coiled wire to the annuli- 20--2I strain loops 2223 are for e in such ends between their point of attachment to the annuli and the ends of the coil C.

Suitable insulating gasketsid. and are. provided to overlie the inner facesof the annular members 26 and 21 and the end faces of, the cylindrical coil C.

In the construction and assemblageof the .resistor as shown in- Figs. 1 to '7 the spool and c'oil assembly B isv made asshown in Fig. 4; the

annulusifi being first positioned on-the core I5 to abut the flange IS with the gasket. 24 abutting and covering the inner face of the annulus 20. The coil C is then provided on the core I5 with one end portion of the resistance. Wire thereof slightly extended from thecoil and formed into the strain loop 22 the outer endof which is'a'ffixedj to the; annulusfifl as before stated. I The other end portion of the resistance wire of 'the into the coil C is then formed into the strain loop 23 which is then welded to the annulus 2I which annulus is then positioned on the free end por tion of the core I5 in loose relation to the core and coil with the gasket 25 interposed between the annulus 2| and the adjacent end of the coil C. The assembly B and shell A are then put together by inserting the core and coil in the open end of the shell A as shown in full lines in Fig. 6 with the outer end of the post E presented to the slot I l. The core and coil are then advanced into the shell with the outer end portion of the post E passing through the slot I4,

as indicated in dotted lines in Fig. 6; the core and shell being thus advanced until the free end of the core I5 is moved into the opening II and disposedin close abutting contact with the marginal portion of the end wall In surrounding the openin ii and with the anulus 2| abutting the end wall It and with the coil cylinder C abutting the gasket 24 as indicated in broken lines in Fig. 6. The flange IE will then be disposed in its engaged position with the shell A and with the post D arranged in the slot I2.

The posts D and E will then pro'ect radially from the shell A to afiord connections for electrical conductors with which the resistor is to be associated.

.Where the assembly B is formed as shown in Fi g. 8, that is without the radial posts D and E and with the terminals a and b of the coil C leading from the ends of the core l5, the shell jAis applied over the assembly and disposed with its open with the applying the fr'eeend wall It theouter end of the core IE will be received in the opening II and engagedwith the wall iii.

In the construction shown in Fig. Qthe res stor is provided with copper wire terminals 2526 which lead into the open ends of the core i5 and through openings I8'-I9' in the core and have flattened ends 28-28 to which the termi- Inals of the wire coil C are attached by weld joints 0. Metal grommets 29-29 are fitted in the ends of the core and have holes 3ll-3II through which 7 the terminals 23- 45 extend, which terminals are anchored in the romtrets by solder plugs 3l-3i appliedin a molten state in the open outer end of the grommets against fiber plugs 3 l 3i after completing the assembl y. The plugsiSL-Si also serve to seal the holes 3ii 3fl.lead ing to theopenings I 8- i 9' thus sealingthe latter.

,In the construction shown in Figs. 10-12 wherein the end wall Ill is assembled on the shell A, the innerface of the wall I 0 as well as that of the flange H3, is formed with an annular reeess 32in which the annuli 2! and 20 are seated and arranged with the terminals E and D there- 'on extehded radially from the end wall and a flange through the slots I2 and I4 of the shell;

v The'iree end wall it, likethe flang IS form closuresiorltheends' of the cylindrical shell A and are snugly fitted to the latter "as" is tli con- 5 nection between the core and the end wall I 0, and if desired the joints between the parts may be sealed by a suitable adhesive. The slots 82-!4, and openings l8-|9 and I8-l9' are sealed around the terminals extending therethrough.

I claim:

An electrical resistor comprising a cylindr'cal shell open at one end and having an end wall at its other formed with an axial circular opening, a spool embodying a resistance coil receiving core insertable in the open end of said shell with an end thereof inserted in said opening in snug engagement with th portion of end wall surrounding said opening, an inteannular ilange on the other of said core abutting the open end said shell having a reduced inner marginal portion abutting the inner peripheral portion of said shell adjacent the open end thereof, a cylindrical coil of resistance wire encompassing said core, and terminals on coil leading exteriorly of said shell.

electrical comprising a cylindrical shell open at one end having an end wall at its other end formed with an axial circular opening, said shell being formed with a slot adjacent end thereof, a spool embodying a cylindrical core having a free end and formed with an integral annular flange at its other end, a cylindrical coil of resistance wire encompassing said core having terminals leading from said coil; spool and coil being arranged within said shell with said flange tightly abutting the open end of the shell and with the free end of said core extending into said end Wall opening snug rent with the portion of the end wall surrounding said opening, and with said terniin extending through the slots in said shell. The structure c lied for in claim 2 in which the terminals each comprise a rigid electrically conductive annulus encircling the core adjacent end of the coil and connected to the latter a post on and leading from said annulus and extending from the latter through one of the slots n said shell and pr ing from the latter.

4?. in electrical resistor comprising a cylindrical shell having an open end and a closed end. with closed end formed with an axial circular opening, said shell having a slot adjacent each end thereof, a spool embodying a cylindrical core having a flanged end and a free end, a metallic annulus encompassing each of the ends of said core, a post on each annulus projecting through of the slots in said shell, a coil of resistance wire encompassing said core having ends one or which is electrically connected to one annulus and the other of which is electrically connected to th other annulus; said core being arranged within said shell with its flanged end 6 engaging the open end of said shell and with its free end engaged with the opening in the shell end wall.

5. The structure called for in claim l in which said shell and spool are formed of a non-hygroscopic heat resistant material with high dielectric trength and very low co-efficient of expansion and highly resistant to thermal sh ck.

6. Th st ucture called for in claim a in which the resistance wire comprises nicrome wire and which the ends of said Wire are connected to their respective annulus through a strain loop and by a weld joint.

7. An electrica resistor comprising a cylindrical shel having open ends, an end wall closing one end of said shell formed With an axial circular opening, spool and coil assembly in said shell comprising a tubular core having open ends and formed with a flange on one of its ends seated on and engaging one end of said cylindrical shell, said core having a free end extending into the opening in said end wall and snugly engaged by the latter, a coil of resistance wire encompassing said core having terminals, said terminals extending through said core and out the open ends thereof.

8. The structure called for in claim 7 together with metal grommets which are inserted in the open ends of the core through which the terminals lead, and solder plugs in said grommets anchoring the terminals therein.

9. An electrical resistor comprising a cylindrical shell, an end wall closing one end of said shell and provided with an axial opening, a spool and coil assembly in said shell comprising a tubular core having open ends and a flange on one of its ends seated on and engaging the other end of said cylindrical shell for closure thereof, the other end of said cor being free and extending into the opening in said end wall and snugly engaged by the latter, a coil of resistanc wire encompassing said core having terminals, said terminals embodying annuli inset in said flange and end wall and posts extending from the annuli through said shell and projecting therefrom, and insulation gaskets interposed between said annuli and the ends of said coil.

HENRY C. GORDEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,387,522 Thornton Aug. 16, 1921 l.,7i5,872 Stickney Feb. 4, 1930 1,872,068 Brown Aug. 16, 1932 2,243,047 Addy et a1. July 8, 1941 2,547,465 Mitchell et a1 Apr. 3, 1951 2,556,973 Nickells June 12, 1951

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