US2303958A - Electrical resistance pad device - Google Patents

Description

Dec. 1, 1942. w c sc 2,303,958

ELECTRICAL RESISTANCE PAD DEVICE Filed Sept. 24, 19 41 2 Sheets-Sheet l INVE N TOR W. c. SCHM/D r ATTORNEY Dec. 1, 1942. w. c sc m p'r 2,303,958

ELECTRICAL RESISTANCE PAD DEVICE Filed Sept. 24, 1941 2 Sheets-Sheet 2 F/GB 'YNVE/VTOR Y WCSCHM/DT ATTORNEY Patented Dec. 1, 1942 UNlTED STATES entrant OFFICE.

Bell Telephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New York Application September 24, 1941, Serial No. 412,058

3 Claims.

This invention relates to electrical resistance devices and more particularly to resistance devices in which a plurality of resistance elements Fig. 3 is a lower end view of the device shownin Fig. l but minus the cover on the lower end of the casing;

Fig. 4 is a view in perspective of the connector block and with a portion of the outer covering broken away to show interior portions of the structure;

Fig. 5 is an exploded view of the parts shown in Fig. 1;

Fig. 6 is a View of a lower portion of the casing minus the lower cover and with terminals of the resistance elements and of the terminal block projecting below the lower end of the casing. A strap connection is shown electrically connecting two of the terminals;

Fig. 7 is a top plan view of a blank from which the body of the casing is formed; and

Fig. 8 is a top plan view of a blank from which the lower cover is formed.

In such cases where resistance pads are required in an electrical system it is common practice to select and assemble a plurality of resistance elements and to electrically connect the resistance elements to form the required resistance pads. The resistance elements may be of various forms and values. Some of the resistance elements employed and particularly in electrical communication systems are known as fiat type resistances. These resistances are usually separately mounted on a supporting frame and in order to connect them to form the required resistance pad conductor wires are connected to the terminals of the resistances to form strap connections between the various resistance elements. A relatively large number of strap connections are often required to interconnect the resistance elements and to connect the resistance elements to suitable terminals so that the resistance elements will be combined to form the required resistance pad. The strap connections and the wires leading to the terminals are rather loosely arranged and present an untidy appearance. The wiring operations are costly and somewhat confusing.

The present invention provides a neat and compact resistance pad. The resistance elements are enclosed in a casing particularly adapted to hold them together as a unit and which may be mounted on a suitable support. A connector block is provided in the unit to facilitate interconnecting the resistance elements and to reduce the number of wires required in making the interconnections. The terminals of the resistance elements and certain terminals of the connector block and the wires forming the interconnections are enclosed in and protected by a removable lower cover of the casing structure.

Fig. 1 shows a resistance pad unit 9 embodying the invention and comprising a plurality of flat type resistance elements 10, H, l2, l3, l4 and IS, the connector block l6 and the casing ll,

The casing I! is made in the form of a rectangular can comprising the body I8, an apertured top cover l9 and a removable lower cover 20. The parts of the casing H are made of sheet material suitable for fabrication into a substantially rigid protective casing for the resistance elements and the connector block. For the purpose of simplifying the description of them and not in the sense of limiting the invention to the use of such material, it will be assumed that they are made of sheet metal of the type commonly used in making can type containers. The body 18 is made from a cut-out blank 2| of the sheet material as shown in Fig. 7. The blank 2! is apertured at 22 and is upwardly folded along the dotted lines 23 and 24 and upwardly along the dotted lines 25 and 26. The flaps 21 and 28 are folded upwardly along the respective dotted lines 29 and 30. When the blank 2| is folded along the lines mentioned it will be in the form of the partly formed body 3! shown in Fig. 5. Further folding along the dotted lines 23, 24, 25 and 26 will bring the partly formed body 3| to the form of the body 18 shown in Figs. 1 and 6. The front wall of the casing is formed by two parallelly arranged half sections which are partly overlapped by the folded up flap 28. The back wall is of similar construction. After the body IB has been formed in the manner described, the resistance elements I0, H, l2, l3, l4 and I5 and the connector block I6 are inserted in the body l8. The top cover I9 is then applied to the body 18. The top cover l9 has a downwardly turned.

edge flange 32 to encompass the upper end of the body l8 and is welded or otherwise fastened along the edge flange 32 to the upper end of the body I8.

The lower cover 20 is formed from a suitably cut-out blank 33 shown in Fig. 8. The blank 33 is folded upwardly along the dotted lines 34 and 35 and upwardly along the dotted lines 36 and 31. It is also folded upwardly along the dotted lines 38 and 39 to form the partly completed lower cover 40 shown in Fig. 5. Inwardly extending embossings 4i and 42 are formed in the walls 43 and 44 of the part 40 shown in Fig. 5. Further folding along the dotted lines 34, 35, 36, El, 38 and 39 will bring the partly completed lower cover shown in Fig. to the form of the lower cover 253 shown in Fig. 1. In its completed form the front wall of the cover 25 is cooperatively formed by the wall 45 and the two walls 46 and 4?, the walls 45 and 4! overlapping a portion of the wall 45 and being spot-welded or otherwise secured to the wall 45 at the points 48 and 39. The back wall of the lower cover 20 is formed in the same manner as the front wall. It will be seen by looking at Fig. 1 that the wall 45 is about half the height of the lower cover 29 and abuts against the lower end of the body [8 when the cover 2% is applied to the body I8. The inwardly directed embossings 4| and 42 eX- tend over the upper edge of the flap 28 to hold the lower cover 20 from accidental dislodgement from the body l8. A U-shaped handle 55 is secured to the lower end of the lower cover 20 to facilitate handling the lower cover 28. When the lower cover 29 is being applied or removed the walls 45 and 4'! will be flexed sufficiently in the region of the embossings 4i and 42 to allow passing of the embossings 4i and 42 over the upper edge of the flaps 27 and 28.

The resistances H], H, l2, [3, I4 and I5 are flat type resistances comprising a rectangular body portion 5% and terminals 52 and are inserted in the body 58 of the casing I! so that the terminals 52 extend through the aperture 22 in the lower end of the body l3. as shown in Fig. 6. It will be understood that the resistances comprise in each case a resistance element enclosed in the insulating body portion 5| and that the terminals 52 of each resistance are electrically connected to the resistance element.

The connector block l6 as shown in Fig. 4 comprises a laminated rectangular block 53 of insulating material equipped with two sets of terminals 54- and 55. The terminals in each set 54 and 55 are relatively long fiat strips of conducting material and are secured to the block 53 by means of eyelets or rivets 56 which project through apertures provided in the terminals and into the block 53. The terminals are arranged in parallel spaced relation and have end portions extending longitudinally outward of the block 53. The set 54 is shown as comprising four terminals 5?, 55, 59 and E3, the projecting end portions of which are notched at El to facilitate the connecting of wires thereto. The set 55 is also shown as comprising four terminals 62, 63, 64 and 65 with the projecting end portions apertured at 65 to facilitate the connecting of circuit wires thereto. The terminals 51 and 58 are rather widely spaced apart on one face of the block 53 and the terminals 59 and Gil are likewise spaced apart on the opposite face of the block 53. The terminals 62 and 63 are located between the terminals 5? and 58 and extend in parallel spaced relation therewith. The terminals 64 and 65 are located between the terminals 59 and 60 and extend in parallel spaced relation therewith. Each terminal in the set is electrically connected by means of a conducting strap $31 to an adjacent terminal in the other set at some convenient point along the structure of the connector block l6. It will be seen that the projecting ends of the terminals in the set are in more closely grouped formation than the projecting ends of the terminals in the set 54 and as shown in Figs. 1 and 2 project upwardly through an aperture 58 in the top cover l9. The terminals 53, S4 and 65 therefore project outwardly of the casing structure and may be used as exterior terminals of the resistance pad. A covering 59 of insulating material is provided on the connector block IE to cover all but the projecting end portions of the terminals mounted on the block.

Supported on the top cover 59 projecting upwardly therefrom are spaced studs 73 and H equipped with nuts 12 so that the resistance pad unit may be supported on a supporting frame or rack, not shown. Spaced embossings I3, 74, '15

and 76 are formed on the upper surface of the top cover I 9 to bear against the supporting frame or rack above-mentioned. An apertured insulating strip ll is provided as a closure for the aperture 5B in the top cover 19 and to assist in maintaining the projecting ends of the terminals 62,

5 5 and 55 in required spaced relation.

The terminals 57, 58, 59 and 50 of the connector block ii: and the terminals 52 on the resistances M, H, l2, l3, I4 and 15 project through the aperture 22 in the casing l8 and below the lower end of the casing I? as shown in Fig. 6. These terminals may be selectively and electrically connected by means of strap conductors 18 to form various desired combinations of the resistance elements and to bring the resistances into electrical connection with the terminals on the terminal block IS. The strap conductors I8 may comprise insulated wires or other conductors suitable for the purpose and may be arranged so that they serve as connecting means between one or more of the resistance devices and the connector block. In Fig. 3 which shows one of the many possible arrangements of the strap conductors the resistances 15, ll and I2 are connected in series by means of strap conductors 78 and are electrically connected by means of strap conductors '18 to the terminals 59 and of the connector block l6. Since the terminals 59 and 60 are electrically connected by means of conducting straps 62' the outside terminals for this combination of resistances will be the terminals 64 and proecting through the top cover l9. Again as shown in Fig. 3, resistances l3 and I5 are electrically connected by means of strap conductors l8 and other strap conductors 18 are provided to electrically connect this combination of resistances to the terminals 5'5 and 58 of the connector block 48. In this case the outside terminals for this combination are the terminals 52 and 63 of the connector block [6. It is obvious that various combinations of resistances may be made by suitably connecting the terminals thereof by means of the strap conductors l8 and that the connector block IE facilitates the combining of the resistances to form a required resistance pad unit.

The lower cover 20 when placed in the position shown in Fig. 1 serves in cooperation with the lower end of the casing l8 and with the lower ends of the resistances enclosed in the casing as a housing for the terminals 52 of the resistances, the terminals 51, 53, 59 and 63! of the connector block I6 and the various strap conductors l8 employed in making the required electrical connections. The engagement of the upper ends of the Walls 45 with the bottom of the casing l8 prevents too far thrusting of the lower cover 26 on the casing 18. Since the inwardly extending embossings 4i and d2 snap over and engage the upper edges of the flap portions 2! and 2B of the casing l3 accidental dislodgment of the lower cover 28 from the casing H) is prevented,

What is claimed is:

1. In an electrical resistance pad device comprising a plurality of resistance elements stacked together in combination, a tubular casing holding said resistance elements in stacked condition, an end cover closing one end of said casing and extending below the lower end of said casing to form in cooperation with said casing and the lower ends of said resistance elements a lower compartment, an apertured top on said casing, spaced mounting studs on said top providing means for mounting said casing on a support, a connector block disposed between two of said resistance elements, a set of terminal strips secured to said connector block and having end portions extending into said lower compartment, said end portions being electrically connected to said resistance elements, a second set of terminal strips secured to said connector block and having end portions projecting through said top and conducting straps electrically connecting terminal strips in the first set to terminal strips in said second set.

2. In an electrical resistance pad device comprising a plurality of flat type resistance elements in combination, a connector block, an apertured can type casing holding said resistance elements and said connector block in stacked condition, an apertured top cover on said casing, means supported on said top cover to mount said casing on a support, a set of long strip terminals supported on said connector block and having end portions projecting outwardly through said top cover, a second set of long strip terminals supported on said connector block and electrically connected to the first-mentioned set of terminals and extending downwardly through the lower end of said casing, terminals on said resistance elements extending downwardly through the lower end of said casing, conductors electrically connecting said second set of terminals to the terminals of said resistance elements, a removable lower cover on said casing enclosing said second set of terminals and the terminals of said resistance elements and means on said casing and on said lower cover to pre vent accidental dislodgment of said lower cover from said casing.

3. In an electrical resistance pad device comprising a plurality of flat type resistances in combination, a connector block of the same gen eral form as said resistances, an apertured can type casing enclosing and holding said resistances and said connector block in stacked condition, an apertured top cover secured to the upper end of said casing, means on said top cover for mounting said casing on a support, two sets of long strip terminals supported in spaced relation on said terminal block, one of said sets having end portions extending through said top cover, the other set having downwardly projecting end portions extending through the lower end of said casing, conducting straps supported on said connector block and electrically connecting said sets of terminals, terminals on said resistances extending through the lower end of said casing and in spaced relation with the downwardly projecting end portions of one of said sets of long strip terminals, conductors electrically connecting the terminals of said resistances to the set of terminals having the downwardly projecting end portions, flap portions on the lower end of said casing, a lower cover removably supported on the lower end of said casing and serving in cooperation with the lower end of said casing as an enclosure for the projecting ends of one of said sets of terminals, the terminals of said resistances and said conductors, and embossings on said lower cover adapted to snap over and frictionally engage the flap portions on said casing to prevent accidental dislodgment of said lower cover from said casing.

WILLIAM C. SCI-m/IIDT.

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