Electrical Terminal Block For Interconnecting A Plurality Of Conductors

Abstract

Electrical Terminal Block comprises an insulating base member having a stack of individual clamping blocks mounted thereon. Individual terminals devices are contained in the stacks between adjacent clamping blocks and extend laterally on each side of the stack. The ends of the terminal devices are provided with terminal means in the form of inwardly extending slots which are adapted to receive insulated wires. The preferred form of the invention may also include means on each terminal device for trimming the end portion of a wire concomitantly with insertion into the slot. Devices of this type are commonly used in the communication industry for permanently or semi-permanently interconnecting a multiplicity of conductors from a plurality of multi-conductor cables.

Parent Case Text

BACKGROUND OF THE INVENTION

This application is a continuation in part of application Ser. No. 805,160 filed Mar. 7, 1969, now U.S. Pat. No. 3,617,983, which is hereby incorporated by reference in its entirety.

Description

The instant invention is directed to the achievement of an improved terminal block for making permanent electrical connections between a relatively large number of conductors and which permits changing of the interconnections when required. The invention is herein disclosed as incorporated into a so-called line terminal block of the type used in the telephone industry in main and intermediate distribution frames although other uses for the invention will be apparent to those skilled in the art.

Line terminal blocks are used in very large numbers in the telephone industry in main and intermediate distribution frames for forming interconnections among a plurality of individual cables, and jumpers each of which contains a plurality of pairs of electrical conductors. When the conductors of a plurality of cables and jumpers are interconnected on a line terminal block, the interconnections made are permanent in the sense that they are never broken until additional cables are brought into the distribution frame and/or some cables are removed from service as where the telephones are removed from a building being dismantled or telephones are added to, or taken from, the service supplied to a portion of a building. A suitable line terminal block should, therefore, be capable of interconnecting a relatively large number of electrical conductors. Furthermore, while the interconnections made are permanent in the sense that they may not be disturbed for years, it should also be possible to change the connections when required. Finally, and because of the complexity of the wiring in the telephone industry, it is desirable that the technician or installer making the interconnections should be able to do so rapidly and with a minimum possibility of error.

In the past, line terminal blocks have been provided with a plurality of simple terminal posts to which the individual conductors may be soldered or on which the conductors may be wrapped in the known manner. Soldering of the conductors on a line terminal block is time consuming and subsequent changes to the wiring of the block is also time consuming because of the necessity of removing soldered wires from their terminals. Wrapped type connections may avoid the necessity of soldering (although they are sometimes soldered after being wrapped) but do not provide as high a wiring density in the block as is desired. Furthermore, it is necessary, with many types of wrapping tools, to remove the insulation from a conductor before it can be wrapped onto a post.

The instant invention is directed to the achievement of an improved terminal block capable of forming interconnections among a large number of electrical conductors. It is an object of the invention to provide an improved terminal block which is suitable for use in the communications industry as a line terminal block. A further object is to provide a terminal block which is capable of interconnecting a relatively large number of conductors in a very limited space. A still further object is to provide a terminal block having terminals therein to which insulated wires can be connected without stripping of the insulation. A still further object is to provide a terminal block having terminals therein which have means for trimming the end portions of the conductors when they are connected to the terminals. A still further object is to provide a modular type terminal block which can be assembled with varying numbers of terminals depending upon the needs of an immediate situation.

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 detail below and which is shown in the accompanying drawings, in which:

FIG. 1 is a perspective view of a typical line terminal block in accordance with the principles of the invention.

FIG. 2 is a top plan view of the terminal block of FIG. 1 illustrating the manner in which the conductors are led to opposite sides of the block and connected to the terminals in the block.

FIG. 3 is a fragmentary perspective view of an individual clamping block and illustrating the manner in which the Terminals are mounted in the clamping block.

The herein disclosed embodiment of the invention 2 comprises a terminal block composed of a rectangular base plate 4 and a stack generally indicated at 6 of individual clamping modules 8 containing a plurality of individual terminal devices 14 arranged in orderly rows and columns in the stack. The stack 6 is made up of an elongated base member 10, a cap member 12, which may be identical to base member 10, and a plurality of intermediate clamping blocks 8 between the base and cap members. It will be understood that, within limits, any desired number of clamping blocks may be provided in the stack to supply the necessary number of terminal devices 14 to interconnect a specific number of conductors. The base and cap blocks 10, 12 and the clamping blocks 8, are secured to the base member 4 by means of suitable fasteners 22 which extend through the stacked blocks and into the base member. The base member and the individual blocks stacked thereon may be of any suitable insulating material such as a phenylene oxide resin (Noryl) which can be molded inexpensively.

Under normal circumstances, a large number of terminal blocks 2 are mounted on a mounting frame and openings 16 are accordingly provided at the ends of the base member 4 for the accomodation of suitable mounting screws. The individual conductors 20 are led toward an individual terminal block from the rearward side of the base member 4 and extend through elongated openings 18 on the base member on each side of the stack 6. The conductors are then dressed towards the appropriate terminal devices 14 and connected thereto in a manner described below.

Referring now to FIG. 3, each terminal device 14 comprises an intermediate channel-shaped shank portion 24 having terminals 26 on its ends. The terminal on the right in FIG. 3 comprises the first, second and third plate-like sections 28, 30 and 32 which are formed by reverse bends 34 and 36 in the end of the terminal as shown. The final plate-like section 32 does not extend to the end of the terminal portion of the device but only partially towards the end so that it provides a transversely extending edge 40 which functions as a shearing edge when a wire is inserted into the terminal. The wire receiving means on each terminal on the end of the terminal device comprises inwardly directed slots 38 which extend into the reverse bend 34 and towards the second bend 36 in both plate sections 28, 30. It should also be noted that these slots extend beyond the transversely extending shearing edge 40.

When a wire is connected to a terminal on the ends of one of these terminal devices 14, it is positioned with its axis extending transversely of the end portion of the terminal and in alignment with one of the slots. It is then pushed into the slot until the edges of the slot penetrate the insulation of the wire and establish electrical contact with the conducting core of the wire. At the same time, the end portion of the wire which extends beyond the shearing edge 40 is severed from the wire by this shearing edge in cooperation with a suitable insertion tool. The above identified application Ser. No. 805,160 shows one form of insertion tool and application Ser. No. 66,050 filed Aug. 21, 1970 shows a more advanced type of hand tool which can be used on terminals of the type shown in the drawing.

Each of the clamping blocks 8 is provided with transversely extending slots 42 on one of its longitudinal sides the width of which is substantially equal to and slightly less than the distances between the outwardly directed surfaces of the sidewalls of the shank portions 24 of the terminal. Additionally, a central boss 44 is provided in each slot 42 and a central hole 46 is provided in the web portion of each terminal device. The terminal devices 14 are thus assembled to the clamping block by merely locating the holes 46 of the terminal devices in alginment with the bosses 44 of the slots 42 and forcing the terminals inwardly as shown in FIG. 3. When the clamping blocks are secured to each other and to the base member 4 as shown in FIG. 1, the terminal devices will then be held firmly in position with their end portions spaced from the sides of the stack. It should be noted that the end portion 26 of the terminal devices 14 will extend obliquely with respect to the intermediate shank portion 24, an orientation which has been found to be advantageous to the technician or installer when he is interconnecting a plurality of conductors by inserting the wires thereof into the slots of the terminal device.

In conventional wiring practice, the technician first leads the wires through the appropriate one of the openings 18 in the base member 4 and locates them with their axes extending between two adjacent rows of terminal devices and with their end portion extending forwardly as shown in FIG. 1. He then selects the appropriate wires and locates them in a slot 38 in the desired terminal. He may prefer to position several wires in slots of the terminals before he performs the final insertion operation with a suitable hand tool as disclosed in application Ser. No. 66,050. When the wire is inserted, the end portion thereof which extends beyond the shearing plate section 32 is severed by the insertion tool in cooperation with the shearing edge 40 of the terminal as explained above.

As also explained in application Ser. No. 805,160 it is sometimes desirable to lead a wire from one terminal device 14 to which it is connected to a second or even a third terminal device. To this end, slots 48 may be provided in some of the shearing members or shearing plates 32 of some of the terminals. Upon insertion of a wire into a slot in the plate sections 28, 30 of the terminal shown on the left in FIG. 3, the end portion of the wire will then be forced into the slot 48 of the plate section 32 of this terminal. This wire will thus not be severed or trimmed and it can be led from this terminal to a further terminal in the stack.

Claims

What is claimed is:

1. A terminal block for interconnecting a plurality of insulated wires, said terminal block comprising:

an insulating base means, a plurality of clamping blocks on said base means, said blocks being positioned one on top of the other to form a stack,

a plurality of terminal devices, each of said terminal devices comprising a shank portion having wire connecting means on its ends,

each of said wire connecting means comprising a metal plate having one reverse bend therein to form a pair of parallel plate sections connected by a first bight, at least one slot means extending axially from an end of said connecting means into said first bight and into said plate sections to define aligned slots in said plate sections and a gap in said bight, at least one of said aligned slots having a first root portion of a width less than the diameter of the conducting core of said wire, the width of said slot adjacent to said gap being sufficient to permit movement of said wire laterally of its axis through said gap and into said first root portion to cause the edges of said first root portion to penetrate the insulation of said wire and establish electrical contact with said conducting core of said wire,

said shank portions of said terminal devices being clamped between adjacent blocks of said stack and extending from the sides of said stack whereby

wires extending towards opposite sides of said stack can be connected to each other by inserting said wires into the said slot means of one of said terminal devices.

2. A terminal block as set forth in claim 1 wherein said ends of said terminal devices are laterally enlarged relative to said shank portions, said slot means on each end of each of said terminal devices comprising a plurality of parallel slots.

3. A terminal block as set forth in claim 1 wherein the other said aligned slot includes a second root portion, said second root portion having a width greater than the width of said first root portion and less than the diameter of said insulation of said wire whereby, upon movement of said wire laterally of its axis through said gap and into said second root portion the edges of said second root portion penetrate said insulation to mechanically secure said wire in said wire connecting means.

4. A terminal block as set forth in claim 1 wherein said wire connecting means includes a third plate section and connected by a second bight to one of said pair of plate sections, said second bight being on the opposite side of said plate sections from the side on which said first bight is located, said third plate section having a width as measured between said bights, which is less than the width of said first named plate sections, said third plate section being cooperable with an insertion tool to shear a wire extending past said third insertion of said wire into said slots.

5. A terminal block as set forth in claim 4 wherein said third plate includes at least one opening therein in alignment with said root portions of said slots in said first named plate sections to permit connection of an intermediate portion of a wire to said wire connecting means.

6. A terminal block as set forth in claim 1 wherein said terminal devices are disposed within said stack of said terminal block so that a plane passing through said slot means is perpendicular to said base means and to said stack whereby, said slot means are generally aligned toward said base means to minimize the length of each said wire required for it to be extended from said base means to said wire connecting means.