US2274845A - Resistance device - Google Patents

Description

March 3, 1942. R A. OGG

` RgsIsTANcE DEVICE Filed Feb. 21,` 19401 2 Seets-sheet 1- /Nl/ENTOR R. A, OGG

A TTORNE Y March 3, 1942. R. A. vo'cacs RESISTANCE DEVICE Filed Feb. 21, 1940 2 Sheets-Sheet 2 /NVENTOR RA. OGG

A TTORNEV Patented Mar. 3, 1942 RESISTANCE DEVICE Robert A. Ogg, Towaco, N. J., assignor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application February 2l, 1940, Serial No. 319,995

3 Claims.

This invention relates to electrical resistance devices and more particularly to a type of resistance device commonly known as a at type resistance device. A resistance device of the type mentioned is disclosed in F. S. Koehendorfer et al. Patent 1,677,240, dated July 17, 1928.

The object of this invention is to improve and simplify the construction of such resistance devices and lower the manufacturing cost thereof.

A feature of the invention resides in the struct'ure and arrangement of terminal members on the device.

Another feature resides in a mounting bracket two terminals has also a channel shaped portion extending the full length of the resistance device and clamped to an edge of the resistance device.

, Extending longitudinally of the channel shaped provided on the device and by means of which the device may be suitably mounted on a support.

Another feature resides in a resistance pad comprising a plurality of the resistance devices and a modification of the mounting bracket which serves as a common mounting means for the resistance devices in the pad.

In the drawings:

Fig. l is a view in perspective of the resistance device equipped with the mounting bracket;

Fig. 2 is a view corresponding to Fig. 1, but with certain parts broken away to disclose inner portions of the structure;

Fig. 3 is a cross-sectional view of the device taken on the lines 3-3 in Fig. l;

Fig. 4 is a view in perspective of a modification of the resistance device and a modified form of the mounting bracket;

Fig. 5 is a view in perspective of a resistance pad made of a plurality of resistance devices and having a mounting bracket common to the resistance devices in the pad; and

Fig. 6 is a view in perspective of a resistance device of the form shown in Fig. 1 but with the mounting bracket located on the other end of the resistance device.

Itis common practice to use in central oilices of telephone systems a large number of fiat type resistance devices. The resistance devices are often mounted side by side in rather closely spaced relation and arranged in rows on a supporting frame and with the terminals of the resistance devices projecting through an apertured panel in the frame and the body portions of the resistance devices projecting normal to the plane of the panel.

In the common and well-known form of the portion is a male threaded stem portion adapted to extend through an aperture in the panel and arranged to receive a nut to hold the resistance device on the panel. The terminals are rather expensive to produce and attach and are found in some cases to be an objectionable form because rather closely spaced resistance devices on the panel are often accidentally short-circuited or cross-connected through a screwdriver or other tool when a wireman or repair man is doing wiring `or repair work on the panel. It has been found that in some cases undesirable capacitance effects are also produced by reason of the form and arrangement of the terminals and the relativelyyclose spacing of the resistance devices on the supporting panel.

My invention provides a cheaper construction of resistance device than the form above mentioned and does not have the objectionable features inherent in that form.

The resistance device shown in Figs. 1, 2 and' Vextending across the Ilat faces of the core I. The strips 3 and 4 and the core I are preferably made of the same kind of insulating material and this material is such that the strips and core may be bonded together to form a substantially homogeneous structure. The material may be, for instance, phenolized asbestos and the parts may be bonded together by applying heat and pressure to the strips 3 and 4 and the core I. The core I except for the endportions 5 is made slightly smaller in width than the strips 3 and 4, the end portions 5 being about the same width as the strips 3 and 4. This arrangement makes the portions of the wire 2 passing over edges of the core I to come about usli with the edges of the strips 3 and 4 as shown in Figs. 2 and 3.

Terminals for the resistance' device are provided in the structure, the number of terminals provided being dependent upon the type of resistance required. In the resistance shown in Figs. 1', 2 and 3, four terminals, 1, 8 and 9 are provided in the structure. Each terminal extends to and is connected to the resistance wire 2 at some predetermined point in the resistance wire. It Will be assumed merely for the purpose of illustration that the terminal S is connected to one end of the resistance wire 2, the terminal 1 is connected to the other end of the resistance wire 2, and the terminals 8 and 9 are each connected to some predetermined intermediate point in the resistance wire 2. If the whole resistance wire 2 is required in a circuit, the terminals 6 and 1 may be brought into connection with the circuit wires. When a resistance of lower value than the total value of the resistance wire 2 is required, the same resistance may be used for this lower value requirement by making connection of the circuit wires to other of the terminals provided. For instance 6 and 9 or 6 and 9 may be brought into the circuit instead of 6 and 1. Other resistance values may also be obtained by other suitable selections of the terminals.

Each of the terminals 6, 1, 8 and 9 is a fiat strip of metal extending almost the full length of the resistance device. The terminals may be conveniently made by cutting or stamping them out from a sheet of metal. One end of each terminal is reduced in width to provide an end lug I0. The lug I is bent to extend normal to the plane of the main portion of the terminal and is then bent again at about 90 degrees to extend in a plane parallel to the plane and longitudinally of the main portion of the terminal. Spaced apertures II, not visible in the drawing, are provided in one end portion of the core I, the apertures I I being adapted to receive the lugs I0 of the terminals. Spaced apertures I2 are also provided in the strips 3 and 4, the apertures I2 being in register with the apertures II in the core I and being adapted to receive the lugs ID of the terminals. The terminals 1 and 8 lie v against the outer face of the strip 3 and with the lugs I0 extending through the apertures I2 in the strip 3, and through the associated apertures II in the core I, and thence through the associated apertures I2 in the strip 4 and so that the end portions of the lugs I0 lie against the outer face of the strip 4. The terminals 6 and 9 lie against the outer face of the strip 4 and with the lugs I0 extending through the apertures I2 in the strip 4, and through the associated apertures II inthe core I and thence through the associated apertures I2 in the strip 3 and so that the end portions of the lugs I0 lie against the outer face of the strip 3. It will be understood that one end of the resistance wire 2 is electrically connected to the lug I0 of one of the terminals and that the opposite end of the resistance wire is connected to another of the terminals. Since the strips 3 and 4 are 1ocated on opposite faces of the core I and the terminals are located on the outer faces of the strips 3 and 4 and the lug portions I0 of the terminals are bent over against the outer faces of the strips 3 and 4, the electrical connections between the resistance wire 2 and the terminals are made by bringing portions of the resistance wire 2 over an edge of the strips 3 or 4 and to the required terminals. As shown in Fig. 2 one end of the resistance wire 2 is brought over the upper edge of the strip 3 and then downward against the outer face of the strip 3 to the lug i0 of the terminal 6 and is electrically connected at I3 to the lug I0 of the terminal S. The other end of the resistance wire 2 is electrically connected to the terminal 1 by bringing the wire 2 over an edge of the strip 3 and over an outer face of the strip 3 and then lsecuring the wire to an outer face of the terminal l. The latter electrical connection is notshown in the drawings since it is hidden by the outer covering of the resistance device. The manner in which it is made can be understood, however, by looking at terminal 8 in Fig. 2. Terminal 8 is shown as being electrically connected to an intermediate portion of the resistance wire 2y a portion of the wire 2 being brought over an edge portion of the strip 3 and over an outer face of the strip 3 and then solder connected at I4 to an outer face of the terminal 9. Terminal 9 is electrically connected to some other predetermined pointof the wire 2 in the same manner as shown for terminal 3, except that in this case the wire is brought over an edge and an outer face of the strip 4 and is electrically connected to an outer face of the terminal 9. Such connections may be made, for instance, by soldering the resistance wire to the required terminal or by providing a suitable lead-in wire between the terminaland the resistance wire at the point required, the lead-in wire being electrically connected to the resistance wire 2 and to the required terminal.

An outer covering I5 of insulating material is provided on the resistance device. This outer covering I5 extends over the main portions of the terminals 6, 1, 9 and 9 and over the outer surfaces of the strips 3 and 4 and the upper and lower edges of the core I. The covering I5 is preferably made of a material adapted to be bonded under heat and -pressure to the strips 3 and 4 and may be made, for instance, of phenolized asbestos applied in sheet form over the outer faces of the strips 3 and 4, the terminals 6, 1, 8 and 9 and over the upper and lower edges of the strips 3 and 4, the core I and the portions of the resistance wire 2 lying adjacent the upper and lower edges of the core I, After the covering I5 is applied the resistance device is subjected to heat and pressure to make the covering I5, the strips 3 and 4 and the core I to become, in effect, a homogeneous structure, with the resistance wire 2 and the main portions o. the terminals 8, 1, 8 and 9 embedded therein. When the heat and pressure is applied to the parts, embossings I6, I1, I8 and I9 are formed on the outer surface of the covering I5 due to the underlying terminals 6, 1, 8 and 9.

The terminals 6, 1, 9 and 9 are made of suicient length to leave leg portions 20, 2|, 22 and 23 extending outwardly from one end of the resistance structure. Each leg Iportion is apertured at 24 to facilitate connecting of the leg portion to a circuit wire and is offset from the plane of the main portion of the terminal. The leg portions 20 and 22 of the respective terminals 8 and 8 are located near the upper edge of the resistance device and the leg portions 2| and 23 of the respective terminals 1 and 9 are located near the lower edge of the resistance device. This arrangement of the leg portions of the terminals leaves a relatively large space at one end of the resistance device to accommodate a portion of a mounting bracket 25, the structure and function of which will be subsequently explained. The lug portion HI of the terminal 6 is located near the upper right corner of the structure as shown in Fig. 2 and the leg portion of this terminal projects frorn the structure near the upper left 4porltion of the resistance device. v This terminal may therefore be made substantially straight from the end on which the lug portion I0 is formed to the point of emergence from the opposite end of the resistance device. The terminal 8 is made vplanes or the main portions ot the respective terminals.. The terminal 1 may be of about the same iorm as the terminal t since the terminal 1 extends in about a straight line from apertures yin the strips 3 and 4 and in the core I. but located in the lower right portion oi the structure to the lower left portion of the device. 'I'he termina'l I follows about the same i'orm as the'terminal t since the lug portion Il oi' the terminal I is located in apertures in the strips l and 4 and in the core I and located above the apertures accommodating the lug portion Il o! theY terminal 1. The terminal l therefore extends for the greater portion ot its length in a plane above that oi terminal 1 and then bends downward to bring the leg portion 22 out near the leg portion 2| of the terminal 1, the leg portions 2| and 2l of the respective terminals 1 and l being oppositely onset from the planes o! the main portions of the terminals.

The mounting bracket 2l is made from a single piece of sheet material capable of being bent to required form. It will be assumed merely tor the purpose of explaining the structure and not in the sense oilimiting the structure to the use oi such material, that it is made o! sheet metal. 'I'he bracket 25 is made in the form of a skeleton casing comprising two reclining T-shaped side wall portions 21 and 28 joined by an integral reclining U-shaped end portion 29 which passes in spaced relation acro an end portion o! the resistance device and in spaced relation with the terminals 6, 1, 8 and t. A T-shaped aperture Il is provided in carlal ide wall portion 21 and 28 to lighten the structure and to reduce capacitance between the wire winding and the bracket. I'he side wall portion 21 bears against one lace of the resistance device and the side wall poring within the spaces denned by the apertures 8|. Ihe U-shaped end portion 20 o! the bracket 2l is apertured and tapped at'spaced points Il and I4 to receive machine screws or bolts,y not shown, ior securing the bracket 2l to a support. The support might be an apertured panel or cross-baroiairame. It willbeseen that the bracket 2l clcly'srips the resistance device and provides a means for supporting the resltsance device on a supporting trame, not shown, that theterminalsl,1,landlarenotutilizedasa supportingmeans for the resistance device and that the terminals do not extend along outer edge portions o! the resistance device, but are for the greater portions of their length enclod in the homogeneous .structure cooperatively -iormed by thestrlps I and 4' and the outer covering Il. Itwillalsobeseen that theterminals C, 1,) and O are substantially ilat strips of metal resistance device. 'I'he upper and lower ends oi v the side wall portion 21 are bent to extend transversely across the respective upper and lower toward the center o! the side wall portion 21. The upper and lower ends o! the side wall portion 22 are bent transversely across the respecand that no expensive machining or forming operations are required to pmduce them.

In Fig. 4 the resistance device l! is made in the same general form as the resistance device shown in Pig. l. The terminals 38, 21, l2 and Il corresponding to the respective terminals t, 1,

I and 0 are in this case, however, led outwardlyv '44 are integral with the side wall portions and 42 and pass in spaced relation across an end portion oi the resistance device 25. 4l is provided in each side wall portion 4I and 42 to lighten the structure and to reduce capacitance between the wlre'winding and the bracket. The upper and lower ends o! the side wall portion 4| are bent transversely across the respective upper and lower edges oi the resistance device and are apertured at 4B to accommodate the tongues 41. The tongues 41 are extensions from upper and lower leg portions 48 and 49 oi the side wall portion 42, the leg portions 48 and 49 being bent transversely across the respective upper and lower edges oi the resistance device 25 and lying in overlapping relation with the respective bent over end portions oi the side wall portion 4i. The tongues 41 are pressed into the apertures 4B to hold the side wall portions 4| and 42 against outward movement in the same manner as the side wall portions o! the bracket 2l inl'ig. lareheldinposition. Theendportions 43 and 44 of the bracket 4l are equipped with threaded studs or bolts il to facilitate mounting oi the bracket 4l. on a support, not shown. It will be sem that the main portions oitheterminals3,21,3landareembedded inthereslstancedevicellandthattheoutspaced portions 42 and 44 of the bracket also in spaced relation with the for.

in Pig. 5 the mounting bracket 6I is conin same ionn as the mounting An aperture o 54 and 5I are shown in Fig. 5 as having only two terminals on each resistance. Resistance devices having more than two terminals may be used, however, if such resistances are required. 'I'he mounting bracket Il may also be made in a different size if the plurality of resistance devices to be supported therein is more or less than four. The resistance devices shown in Fig. 5 are arranged to cooperatively form a resistance pad and are stacked together in iiat faceto-tace relation within the mounting bracket Il. The mounting bracket 5i clamps the resistance devices in the required positions and serves as a mounting bracket common to the resistance devices 52, 53, 54 and 55. Both terminals on each of the resistance devices 53 and I4 have been shortened to leave only stub portions oi the terminals projecting from the end portions of the resistance devices. One terminal on each of the resistance devices 52 and 55 has also been shortened to leave only a stub portion of the terminal projecting from the end of the resistance device. The unshortened terminal 58 of the resistance device 52 serves as one terminal for the resistance pad. The other terminal for the resistance pad is the unshortened terminal l1 of the resistance device 55. The stub portion of the terminal 58 on resistance device 52 is connected by means of a conductor 59 to the stub portion of the terminal 80 on resistance device 5I. The stub portion of terminal 8l on resistance 5l is electrically connected to the stub portion of terminal 62 on resistance device N by means of a conductor 63. Conductor I4 is electrically conriected to the stub portion of terminal $5 on resistance device 54 and to the stub portion of terminal 88 on resistance device 55. The resistance devices 52, 53, 64 and 55 are therefore connected in series and are held together by means of a single mounting bracket 5I which may be secured to a support, not shown.

In Fig. 6, the mounting bracket 25 is identical in structure to the mounting bracket 25 in Fig. l, but is positioned on an opposite end portion of the resistance device to the position occupied in Fig. i.

The resistance devices above described may be given a coating ll of paint to protect them from moisture. The coating il may be extended over the required portions of the resistance devices and over the mounting brackets.

What is claimed is: 1. A resistance device comprising an core of insulating material, a resistance `wire wound thereon, apertured-strips of insulatingmaterial covering said core and said wire, aniinsu-l lating covering over said strips, said covering.

' mediate portions embedded in said covering.

2. A resistance device comprising an apertured core of insulating material, a resistance coil wound thereon, apertured strips of insulating material disposed against opposite faces oi said core and covering said core and said coil, the apertures in said strips being in register with the apertures in said core, terminals extending along outer faces oi said strips and through apertures in said strips and in said.core and hooked into engagement with said strips and said core, said terminals being electrically connected to said coil, a covering of insulating material covering said strips and the terminal portions extending along said strips and covering edge portions of said core, said core, strips and covering being bonded into a homogeneous structure and end portions of said terminals extending longitudinally outward of said structure.

3. A resistance device comprising an apertured core o! insulating material, a resistance wire wound thereon, apertured strips oi' insulating material disposed against opposite faces oi said core and covering said wire, the apertures in said strips being in register with the apertures in said core, terminals for said wire having main portions extending along outer faces o! said strips, end lugs on said terminals extending through the apertures in said strips and cox e and clamping said core and strips together, an outer covering of insulating material enclosing said core, said strips and the main portions of said terminals, said covering, strips and core being bonded together into a homogeneous structure and leg portions on said -terminals extending beyond one end of said structure.

ROBERT A. OGG.

apertured',l

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