Wire-in-slot electrical connections

[57] ABSTRACT

Electrical connecting device comprises a generally Y-shaped member having wire receiving slots extending into corresponding side edges which are adjacent to the bight of the V. The plate sections of the V are preferably kinked in alignment with the slots. Upon insertion of a wire, the plate sections are resiliently stressed by the wire in a manner to cause them to move towards each other. Additionally, the individual plate sections may be flexed by stressing of the kinked sections in the manner of a cylindrical spring.

Claims, 15 Drawing Figures

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PATENTEOM161974 3,824,527

SHEET 1 Of 5

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PATENTED* 16 BH

3,824.527

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PATENTED M l 61974 3.824,527

SHEET 3 OF 5

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PATENTED JUL 161974

3,824,527

SHEET U OF 5

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PATENTEOM161974

SHEET 5 OF 5

3,824,527

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3,824,527

WIRE-IN-SLOT ELECTRICAL CONNECTIONS

BACKGROUND OF THE INVENTION

This invention relates to electrical connections of the 5 type in which a conductor is forced into a slot having a width such that the edges of the slot penetrate the insulation of the conductor and establish contact therewith.

Slotted plate-type electrical connections have been 10 widely used for several years and are being used to an increasing extent under a variety of circumstances. The simpliest form of slotted plate-type connecting device comprises a flat metal plate having a slot formed therein which is adapted to receive the wire. When the ¹⁵wire is forced into the slot, the portions of the plate member on each side of the slot are stressed in the manner of a rigid cantilever beam and by virtue of their stressed condition, electrical contact is maintained with the wire. In these types of slotted plate-type connecting ²⁰devices, contact depends upon an extremely rigid spring system since the cantilever beams of the system are extremely stiff and capable of undergoing only limited elastic deflection.

The instant invention is specifically directed to the ²⁵achievement of a slotted plate-type connecting device having improved spring systems for maintaining the electrical contact with the wire which permit the use of relatively thinner metal stock in the connecting device ₃₀than has heretofore been practical. In general, the invention is directed to the achievement of a connecting device which is efficient in the sense that it has spring systems for establishing electrical contact which utilize the properties of the material from which the contact 35 is made to a high degree. The invention is further directed to the achievement of a connecting device which is inherently rigid and strong and which can be manufactured at a low cost to a high degree of precision. As will be demonstrated below, the principles of 40 the invention can be used in a wide variety of connectors and under a wide variety of conditions.

It is accordingly an object of the invention to provide an improved slotted plate-type electrical connecting device. A further object is to provide a slotted plate- 45 type connecting device having improved spring characteristics. A still further object is to provide a connecting device which can be manufactured from a wide variety of materials and from materials of differing thicknesses. A further object is to provide an improved method of 50 providing the wire receiving slot in a slotted plate-type connecting device.

These and other objects of the invention are achieved in a preferred embodiment thereof which is briefly described in the foregoing abstract, which is described in ⁵⁵detail below, and which is shown in the accompanying drawings in which:

FIG. 1 is a perspective view of one form of connecting device in accordance with the invention which is adapted to be mounted in a printed circuit board, this ⁶⁰view showing the connecting device exploded from the printed circuit board and showing the lower portion of an insertion tool for inserting a wire into the connecting device.

FIG. 2 is a perspective view which is similar to FIG. ⁶⁵1 showing a wire inserted into the slots of the connecting device.

FIG. 3 is a plan view of the stamped blank from which the connecting device of FIG. 1 is formed.

TIG. 4 is a plan view of the blank after it has been kinked in order to size the wire receiving slots.

FIG. 5 is a top plan view of the connecting device of FIG. 1 in its normal condition and prior to insertion of the wire.

FIG. 6 is a view similar to FIG. 5 but showing the connecting device after insertion of the wire and illustrating one mode of stressing the connecting device.

FIG. 7 is a fragmentary view of one of the plate sections of the connecting device of FIG. 1 in its normal condition.

FIG. 8 is a view similar to FIG. 7 but showing the plate section after insertion of the wire, this view illustrating another mode of stressing the connecting device by the wire.

FIG. 9 is a top view of an embodiment of the invention adapted for connecting a tap-wire to a throughwire splice.

FIG. 10 is a perspective exploded view of a connector for forming butt-splice connections between three pairs of wires, this view showing the metallic connecting device exploded from the connector housing.

FIG. 11 is a view of the connector of FIG. 10 showing the parts in assembled relationship.

FIG. 12 is a perspective view of an electrical contact pin having a connecting device in accordance with the invention integral therewith.

FIG. 13 is a view showing an alternative form of contact pin provided with a connecting device in accordance with the invention.

FIG. 14 is a fragmentary perspective view of a multicontact electrical connector containing contact pins of the type shown in FIG. 12, this connector being adapted to connect the conductors of a ribbon-cable to conductors on a printed circuit board.

FIG. 15 is a fragmentary perspective view of a printed circuit board having connecting means in accordance with the invention mounted thereon.

An electrical connecting means 2 in accordance with the invention comprises a generally V-shaped member of conductive sheet metal having divergent platesections 4, 6 which are integral with each other at a bight 8. The connecting means of FIG. 1 has an integral mounting post 10 extending from the bight which is adapted to be inserted through a hole 11 in a printed circuit board 13 and soldered to a conductor on the underside of the board. Wire receiving slots 12,14 in the plate sections 4, 6 extend inwardly and parallel to the bight 8 from the upper side, as viewed in FIG. 1, of the connecting member, the edges 16,18 of this side sloping towards the slots in order to guide the wire into the slots during insertion. Each plate section has a generally semi-cylindrical kink 20 which extends from the inner end 15 of its slot to the lower side of the connecting member. As will be explained below, these kinks serve as resilient springs when the wire is inserted into the slots and contribute to the contact force at the electrical interface of the wire in the connecting means. As will also be explained below, these kinks permit the manufacture of connecting members with extremely narrow slots for the reception of fine gauge wires.

Advantageously, one of the slots, 12,14 has a width which is substantially less than the diameter of the conducting core 22 of the wire and the other slot has a width which is substantially equal to or greater than the

3,824,527 diameter of the core of this wire so that a good electrical contact is obtained at the narrow slot and a mechanical strain relief for the wire is provided by the wider slot.

One form of insertion tool 26 for inserting the wire 5 into the slots has a shank 28 and a central triangular wire pusher 30 which is adapted to move between the opposed faces of the plate sections 4, 6. Additionally, legs 32 depend from the shank on each side of the wire pusher 30 and are spaced from the wire pusher by a dis- 10 tance such that they will engage the wire outwardly of the plate sections so that the tool can move downwardly past the upper end of the connecting device. To insert the wire, it is aligned with the slots 12,14 and the tool is moved downwardly until· the wire has moved into the slots, preferably to the inner ends 15 thereof. As shown best in FIG. 2, the wire will be displaced downwardly between the opposed faces of the plate sections 4,6 and the insulation of the wire will be penetrated as shown in FIGS. 5 and 6.

other as shown in FIG. 6. The plate sections thus have a tendency to return to their normal positions after the wire has been inserted and exert a continuing interface pressure on the wire. This flexure of the plate sections as units towards each other thus provides one mode of spring loading and gives rise to one source of contact force.

Referring now to FIGS. 7 and 8, each plate section will also act to some extent as a spring independently of the other plate section by virtue of the presence of the kink 20 in each plate section. These kinks, serve as semi-cylindrical plate springs which connect the portions of 34, 36 of each plate section on the opposite sides of its slot. As the oversized wire moves into the 15 slot, the portion 34 of the plate-section will tend to be swung into a slight counterclockwise arc when accompanying stressing of the kink 20 and the tendency of the portion 34 to return to the normal conditions gives rise to a further component of contact force for the wire20 slot interface.

Connecting devices in accordance with the invention can be manufactured of any suitable conductive sheet metal such as brass or phosphor bronze. The specific device shown in FIG. 1 is manufactured by simply stamping the blank 2', FIG. 3, with the slots 12', 14' of 25 the blank being substantially wider than the slots in the finished connecting member. The blank is then kinked by forming cylindrical depressions therein in alignment with the slots as shown at 20 in FIG. 4. This kinking operation has the effect of moving the sides of the slots relatively towards each other and is carefully controlled to produce the desired widths in the slots.

This method of manufacture is distinctly advantageous for the reason that there is for any given stock metal, a lower limit to the width of an opening that can be punched in the stock. As a general rule of thumb, it can be assumed that it is impractical to punch an opening in sheet metal which has a width that is less than the thickness of the sheet metal; if smaller openings are punched, excessive tool wear and tool breakage result to an extent that an operation becomes impractical. Slotted plate-type connecting devices frequently must be provided with extremely narrow slots for fine wires; for example, an AWG 32 wire has a diameter of about 0.008 inch and would therefore require a slot having a width of about 0.006 inch or less for effective electrical contact. Under many circumstances, the use of stock metal having a thickness of less than 0.006 inch is totally impractical and conventional punching techniques would not permit the punching of a 0.006 inch wide slot in stock metal having a thickness greater than 0.006 inch. A kinking procedure of the instant invention permits the achievement of these narrow slots regardless of the thickness of the stock metal.

Referring now to FIGS. 5 and 6, the V-shaped connectingdevice of FIG. 1 may be stressed upon insertion of the wire in a manner such that the two-plate sections are pulled bodily towards each other so that these plate sections move from their normal positions (FIG. 5) to the position shown in FIG. 6. This movement of the plate sections towards each other takes place because of the fact that the wire receiving slots 12, 14 are not in alignment with each other but are located such that there center lines extend obliquely of each other and intersect as shown in FIG. 5. As the wire moves downwardly into the slots, it engages the sharp corners of each slot and tends to move the plates towards each

It should be mentioned that FIGS. 5-8 show the deformation phenomena in exaggerated form for purposes of illustration. In a specific connecting device, the flexure of the plate sections towards each other and the displacement of the plate portion 34 may or may not ba apparent upon visual inspection but the forces which give rise to these deformations will tend to cause the movements illustrated in the drawing. It should also be mentioned that a given connecting device in accor³⁰ dance with the invention will not necessarily be significantly deformed in both modes illustrated and one mode of deflection may be of more significance than the other. The actual behavior of the connecting device will be dependent upon such factors as the thickness ³⁵ and physical properties of the metal stock, the wire size relative to the slot widths and the stiffness of the kink 20.

It will be apparent that the advantages of the kink 20 can be realized in the manufacture of connecting de⁴⁰ vices having a single plate rather than a pair of plate sections in accordance with the preferred embodiment of the instant invention. For example, connecting devices of the type shown in U.S. Pat. No. 3,388,370 can to advantage be provided with kinked plates for pur⁵ poses of accurate manufacture of the slot width and the achievement of the spring effect of the kink 20. An individual plate section having a wire receiving slot therein may be stressed, upon insertion of a wire into 5θ the slot, in a manner such that the two parts of the plate ^υ section would move apart but would remain co-planar; in other words, insertion of the wire might cause partial flattening of the kink 20 rather than pivoted movement of one part of the plate section. In both types of con55 necting means (the V-shaped type of FIG. 1 and a simple flat plate having a wire-receiving slot therein) the kink functions as a spring which stores energy for maintaining contact force at the electrical interface.

Aside from the benefits of improved contact force ₆₀ effects described above, the invention provides other advantages. For example, the edges of the slots formed by the intersections of the plate surfaces in the sides of the slots tend to cut into the insulation while the wires are being inserted and this feature results in cleaner ₆₅ and more positive penetration of the insulation. These same comers dig into the wire after it has been inserted and further contribute to the achievement of a long lived low resistance electrical connection. The V-shape

3,824,527 of the connecting device is advantageous in that it is a relatively rigid and stable structural shape even if the counting device is formed of thin stock metal. As will be explained below, this V-shape is well adapted to close spacing of adjacent connecting devices on a 5 printed circuit board and in a multi-contact connector.

Connecting means as illustrated and explained in FIGS. 1-8 can be used for a wide variety of specific connecting devices and for specific purposes. FIG. 9 10 shows a device for connecting a tap wire 40 to a through wire 38, this connecting device comprising two connecting means 42, 44 of the type previously described which are integral with each other along one edge of each plate-section at 46. A connecting device 15 as shown in FIG. 9 can be manufactured by simply stamping the required slots in a blank and bending the blank to form the offset individual connecting means for the tap wire and the through wire.

FIGS. 10 and 11 show a multi-contact connector for 20 forming butt-splice connections between three pairs of wires extending axially towards each other. The connector contains three separate W-shaped connecting means mounted in a housing having a base and a cap section. Each connecting means 48 comprises two sep- 25 arate connecting means 50, 52 which are integral with each other by means of a connecting bight 54. The housing base section 56 has upstanding sidewalls 58 and barriers 60 extending between, and parallel to, the sidewalls to form three separate compartments, one for ³⁰each connecting means 48. The cap section 62 has integral depending flanges 64 with inwardly directed lower ends 66 that are adapted to snap to grooves 68 in the side walls 58 of the base section. Cap section 62 also has depending ribs 70 which are located such that they will ³⁵push the wires into the splice connectors when the cap section is assembled to the base section. The housing may be of any suitable insulating material such as a firm thermo-plastic.

A connecting means in accordance with the inven- ⁴⁰tion can be provided on known types of contact terminals as shown in FIGS. 12 and 13. FIG. 12 shows an electrical contact pin 71 having an enlarged intermediate section 76 which is connected by a neck 74 to a connecting means 72 in accordance with the invention, ⁴⁵the connecting means being oriented relative to the axis of the pin such that it is adapted to receive a conductor 78 extending transversely of the axis of the contact pin. A terminal of this type can be used in an electrical connector as described in FIG. 14 below. ⁵⁰FIG. 13 shows a pin 71α having a connecting means 72α integral therewith, this connecting means being oriented so as to receive a wire extending coaxially with respect to the contact pin.

FIG. 14 shows a multi-contact electrical connector in ⁵⁵accordance with the invention for connecting the individual conductors 82 of a ribbon-cable 80 to the conductors 98 of a printed circuit board 94. The cable 80 contains a plurality of parallel connectors, each of which is surrounded by plastic insulation 84 that ex- ⁶⁰tends between adjacent conductors as a web 86. The connector of FIG. 14 comprises a block 88 of insulating material having cavities extending therethrough in which electrical contact pins 71 are mounted. The connecting means 72 on the upper ends of the contact pins are arranged in a row with the spacing between adjacent connecting means of adjacent terminals being equal to the spacing between adjacent conductors 82 of the cable. To connect the individual conductors 82 of the cable to the connecting means 72 of the terminals, it is merely necessary to locate the cable above the terminals with the conductors in alignment with the slots and insert the individual conductors into the individual connecting means. This inserting operation can be carried out by a tool of the type shown in FIG. 1 or the conductors can be inserted simultaneously by a tool having an inserter for each conductor in the cable. A suitable cover 96 can be provided on the block 88 as shown. The pins 71 are adapted to enter cavities 92 in a complementary connector block 90 which cavities contain contact sockets which are connected by soldering to the conductors 98 on the printed circuit board 94.

FIG. 14 illustrates a further advantage of the invention in that the individual connecting means 72 can be nested within each other and close spacing of the contact terminals in the block 85 can be achieved, notwithstanding the fact that the plate sections are of substantial width.

FIG. 15 shows a printed circuit board 94 having a plurality of connecting means 2 in accordance with the embodiment of FIG. 1 mounted thereon. The post portion of each connecting means extends through the printed circuit board and is soldered to an electrical conductor 98 on the underside of the board. The connecting means 2 are nested within each other so that there is a minimum of space separating adjacent connecting means 2. This view thus illustrates the fact that connections can be made with printed circuit board conductors 98 that are extremely close to each other.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only.