GB2216346A - Electrical junction block with insulation piercing terminals - Google Patents

Abstract

The junction block comprises an insulating, circular cross section, central insulating body (8) on the circular periphery (54) of which two arcuate electrical terminals (4 and 6) are slidably mounted. Each terminal has a wire slot (22) communicating with a lead-receiving opening (24), and a contact arm (18). A lead-receiving groove (53) is provided on each side of the insulating body (8). The body (8) is encased between inter-engaging insulating end plates (10 and 12) with the interposition of a seal (14). A probe can be inserted through slots (109) in the seal (14) to move the terminals (4 and 6) between a first position in which a lead can be inserted through each opening (24) into the groove (53) therebeneath, to a second position, whereby each lead is forced into the corresponding wire slot (22), the edges of which pierce the insulation of the lead to make electrically conductive contact with the metal core thereof and in which second position the contact arms (18) of the terminals (4 and 6) are in electrical contact, so that the leads are electrically connected. For testing the continuity of the leads, the contact arm (18) of one (4) of the terminals (4 and 6) can be depressed by means of the probe to break the electrical contact between the terminals (4 and 6). Plural junction boxes can be mounted side-by-side on a rail engaged by feet (96). <IMAGE>

Description

ELECTRICAL JUNCTION BWCK This invention relates to an electrical junction block for interconnecting insulated electrical leads.

Some known electrical jundtion blocks comprise screw connections for the leads, in which case the leads need to be stripped of insulation at their ends before being terminated to the screw connections. Other known junction blocks comprise slotted plate connections, but in this case the leads must be forced into the slots of the plates by means of special insertion tooling.

The present invention is intended to provide a junction block which does not require the leads to be stripped of insulation and to which the leads can be terminated with the use of only a simple tool, for example a probe.

According to the present invention, an electrical junction block for interconnecting insulated electrical leads comprises an insulating body having an arcuate peripheral surface, first and second arcuate electrical terminals slidably arranged on said peripheral surface in embracing relationship therewith, and each being formed with a contact arm extending toward the contact arm of the other terminal, and with a lead-receiving opening communicating with a wire slot extending peripherally of said body, the terminals being slidable towards each other on said peripheral surface, from a first position in which the lead-receiving opening of each terminal is in register with a lead-receiving recess opening into said peripheral surface, and a second position in which said openings are out of register with said recesses and said contact arms are in electrically conductive contact with each other; whereby a lead inserted through each opening and thence into the groove in register therewith, in said first position of the terminals, is forced into the wire slot communicating with that opening, as the terminals are moved towards said second position, so that the edges of the wire slot pierce the insulation of the lead to make electrically conductive contact with the metal core of the lead.

The terminals can be moved between their first and their second positions, by means of a simple tool, for example, by means of a test probe.

In order that the leads should be firmly anchored to the insulating body as the terminals are moved from their first to their second positions, each recess is preferably in the form of a groove which extends from the peripheral surface of the body across an end face thereof.

In order to facilitate manipulation of the terminals, opposite end faces of the insulating body may be formed with notches, having sidewalls which diverge towards the peripheral surface of the body and intersect it, the notches being offset from one another circumferentially of the peripheral surface, each contact arm having a hole therein through which a tool, for example a probe, can be inserted into one of the notches in the first position of the terminals, to drive the terminals towards their second position.

The side walls of the notches serve to guide the operator in manipulating the tool to move the terminals.

Advantageously, for testing the continuity of the terminated leads, a contact beam on a contact arm of one of the terminals may underlie a contact surface of the other terminal in the second position of the terminals, the contact beam of the one terminal being depressible to disengage it from the contact surface of the other terminal, whereby the circuit between the leads is broken.

The insulating body, with the terminals thereon may be encased between interengaging end plates which are apertured to provide access for the leads and the tool.

Where the junction block is to be sealed, an elastomeric seal surrounding the insulating body may be interposed between the end plates, the seal being provided with grommets for sealing the access apertures.

For a better understanding of the invention and to show how it may be carried into effect, reference will now be made by way of example to the accompanying drawings in which: FIGURE 1 is an isometric view of an electrical junction block for interconnecting insulated electrical leads; FIGURE 2 is an isometric exploded view of the junction block; FIGURE 3 is an isometric view of a sealing member of the junction block; FIGURE 4 is an isometric view showing a plurality of junction blocks according to Figures 1 and 2 mounted to a rail to provide junction block assembly; FIGURE 5 is an enlarged, exploded, isometric view of part of a junction block according to Figures 1 and 2; FIGURE 6 is an isometric view of the rail of Figure 4, and; FIGURES 7 to 10 are diagrammatic, elevational views illustrating successive stages in the termination of the leads to the junction block.

The junction block 2 shown in Figures 1 and 2 comprises first and second arcuate electrical terminals 4 and 6, respectively, a circular, cross-section, a central insulating body 8, insulating end plates 10 and 12, respectively, and a soft, elastomeric seal 14.

As best seen in Figure 5, each terminal 4 and 6, which has been stamped and formed from sheet metal stock, consists of an arcuate plate having a wire connecting portion 16 and a contact arm 18 projecting from the portion 16. Each portion 16 is formed with a lead terminating aperture 20, which is key hole shaped, consisting of a narrow wire slot 22 for gripping the metal core of an insulated electrical lead, and a lead receiving opening 24 communicating with the wire slot 22 at its end nearest to the contact arm 18. Each aperture 20 is disposed centrally of the width of the portion 16 and extends longitudinally thereof, the slot 22 of the aperture 20 terminating at its other end proximate to the edge 26 of the portion 16 remote from the arm 18.Each arm 18 is formed with a circular hole 32 near its free end and being offset towards the continuous arcuate edge 19 of the terminal 4 or 6.

The terminals 4 and 6 differ from one another in the following particulars. The arm 18 of the terminal 6 has a free bifurcated end remote from the portion 16 and comprising prongs 28 and 30, the prong 28 having been bent slightly upwardly (as seen in Figure 5), out of the arc defined by the terminal 6, whereas the prong 30 follows said arc. The arm 18 of the terminal 4 has at its free end remote from the portion 16, a contact beam 34 which extends at right angles to the arm 18 and which lies slightly therebelow.

The body 18 has formed in one end face 44 thereof a V-shaped radial notch 38 having side walls 40 and 42 which diverge radially outwardly of the body 8 to intersect the circular peripheral surface 54 and meet substantially at its axis X-X. A similar notch 39, having side walls 41 and 43 is formed in the other end face 48 of the body 8.

The notches 38 and 39 are offset from each other peripherally of the body 8. Between the notches 38 and 39, the periphery 54 is intersected by a recess 46 having circumferentially spaced end walls 45 and 47 which act as terminal stops and the floor of which is interrupted by a notch 49 extending axially of the body 8 to receive the contact beam 34, as described below. Circular holes 50 in the faces 44 and 48, of the body 8 receive pegs 72 on the end plates 10 and 12 as described below. A lead-receiving groove 52 opens both into the circumferential surface 54 of the body 8 and into its end face 44, an oppositely positioned and similar groove 53 (Figure 2) opening into the surface 54 and the end face 48 of the body 8.There projects radially from the underside of surface 54, at a position opposite to the notches 38 and 39, an axially extending rib 56, for reception in grooves 74 in the end plates 10 and 12 and which also acts as a terminal stop, as described below.

Each end plate 10 and 12 is of substantially overall rectangular shape and is provided proximate to one pair of diagonally opposed corners, with hollow pegs 58 projecting from its inner face 60 for insertion into holes 68 in the other plate 10 or 12, proximate to its other pair of diagonally opposed corners, in which holes 68 the pegs 58 of the first mentioned end plate 10 or 12 are received.

Each plate 10 and 12 has a central, generally circular opening 70 for receiving a respective half of the body 8, there projecting from the base of the opening 70 the pegs 72 which are positioned for reception in respective ones of the holes 50 in the body 8. Zhe groove 74 of each plate 10 and 12, which is formed in the side wall 75 of the opening 70, extends radially of, and axially of, the opening -70. Opposed, lead-receiving recesses 76 formed in the face 60 of each plate 10 and 12, extend through its side walls 78 and communicate with the opening 70, each recess 76 having a mouth 80 tapering inwardly of the respective side wall 78.

Each plate 10 and 12, has respective upper wall portions 82 and 84 which define between them a notch 86, the wall portion 82 having an inclined face 88 defining one side of the notch 86 and the wall portion 84 having a face 90 defining an axially extending hook 90 defining the other side of the notch 86. The wall portion 84 of each plate 10 and 12 is formed with a recess 92 proximate to the hook 90. Near its lower face 94, each plate 10 and 12, has a pair of oppositely directed mounting feet 96.

As shown in Figures 2 and 3, the seal 14, which is made, for example, of soft rubber, comprises a generally rectangular wafer 98 having formed in opposite lateral edges thereof, lead receiving, circular cross section grommets 100 and 101, respectively, the bottom edge of the wafer 98 being formed with a pair of oppositely directed mounting feet 102, circular openings 104 being provided proximate to the corners of the wafer 98, for receiving the plugs 58 of the end plates 10 and 12. The wafer 98 has a central generally circular opening 106 for receiving the body 8, a notch 108 communicating with the opening 106 for receiving the rib 56 of the body 8. There project from the upper part of the wafer 98, and from opposite sides thereof, a pair of grommet lugs 110 and 111 for reception in the notches 92 of the respective plates 10 and 12.The lugs 110 and 119 have probe access slots 109 therethrough. Adjacent to, but spaced from, each lug 110 is an anchoring wedge 112 for reception in the notch 86 of the respective plate 10 or 12 and having at one end, an inwardly inclined surface 114 for engaging the surface 88 and being complementary therewith, on one side of the notch 86, and at its other end, a reduced thickness portion 116 for engagement with the hook 90 on the opposite side of the notch 86.

The junction block 2 is assembled by applying the terminals 4 and 6 to opposite sides of the surface 54 of the body 8 in slidable, embracing relationship therewith, so that each lead receiving opening 24 is aligned with a respective groove 52 in the body 8.

With the terminals 4 and 6 so assembled to the body 8, the rear edge of the contact beam 34 engages against the end wall 45 of the recess 46, the prong 30 being aligned with the sidewall 42 of the notch 38, and the edges 26 of the terminals 4 and 6 abutting opposite sides of the rib 56 of the body 8.

The body 8 is then inserted through the opening 106 of the seal 14 so that the rib 56 of the body 8 is received in the groove 108 of the seal 14. The end plates 10 and 12 are now brought together about the body 8, with the terminals 4 and 6 and the seal 14 assembled thereto as described above, so that each peg 58 of the plate 10 engages in a corresponding hole 68 of the plate 12 and each peg 58 of the plate 12 engages in a corresponding hole 68 of the plate 10, each peg 72 of the plates 10 and 12 engaging in a corresponding hole 50 of the body 8.

Each wedge 112 of the seal 14 engages resiliently in the notch 86 of the corresponding end plate 10 or 12 and the grooves 74 of the plates 10 and 12 receiving respective portions of the rib 56. The recesses 76 of the plates 10 and 12 cooperate to receive the grommets 100 and 101 of the seal 14.

A plurality of the junction blocks 2 may be mounted on a rail 120, which is best shown in Figure 6. The rail 120 has inwardly curled parallel longitudinal margins 122 and a central gutter 124 formed with a longitudinally central hole 126 for a mounting screw, not shown, junction block separating flanges 128 being struck out from the rail 120 on either side of hole 126. As will be apparent from Figure 4, the junction blocks 2 can be mounted to the rail 120 in two groups of contiguous blocks 2, one on each side of the flanges 128, whereby access is provided for using the mounting screw to secure the rail 20 to a support (not shown).

In order electrically to connect an insulating lead L1 to the terminal 6, the lead end is inserted through the grommet 101, through the opening 24 of the terminal 6, and into the notch 52 aligned therewith. A probe P is then inserted through the slot 109 in the lug 110, diagonally, as shown in Figure 7 and along the side wall 40 after which the probe is raised to a vertical position, as shown in Figure 8, so that the terminal 6 is swung slidably along the surface 54 in an anticlockwise (as seen in Figure 6) direction to engage the side wall 40, whereby the lead L1 is forced into the wire slot 22 so that the edges of the slot 22 pierce the insulation of the lead L1 to make electrically conductive contact with the metal core C thereof.In a vertical position of the probe P, the prong 30 of the terminal 6 lies over the notch 38 the prong 28 thereof projecting over the notch 46. The probe P is then withdrawn and a lead L2 is inserted through the grommet 100 and the opening 24 of the terminal 4 so that the lead end lies in the groove 53 on the other side of the body 8. The probe P is then inserted through the slot 109 of the lug 111, diagonally, as shown in Figure 9, through the opening 36 of the terminal 4 and along the side wall 43. The probe P is then raised to a vertical position, as shown in Figure 10, to engage the side wall 41 of the notch 39 whereby the lead L2 is forced into the slot 22 of the terminal 4 so that its core C is electrically connected thereto, as the terminal 4 slides along the surface 54 in a clockwise (as seen in Figure 5 sense) about the axis X-X. As the probe P is advanced to its vertical position, the contact beam 34 passes under the prong 28 to engage the end wall 47 of the notch 46 so as to lie over the groove 49 and to engage the arm 18 of the terminal 6 from below, to make electrically conductive contact therewith.

Electrical continuity between the leads L1 and L2 can be broken by inserting the probe P through the slot 109 of the lug 110 to engage the arm 18 of the terminal 4 so as to depress the contact beam 34 out of engagement with the arm 18 of the terminal 6, where electrical continuity of the leads L1 or L2 is to be tested. Electrical continuity of the lead L2 can be tested by inserting the probe P through the slot 109 of the lug 111 to engage the probe with the arm 18 of the terminal 6.

As an alternative to breaking the electrical connection between the terminals 4 and 6 by means of the probe P, a mechanical switching device could be provided on the junction block for depressing and releasing the contact beam 34.

Claims (12)

CLAIMS:

1. An electrical junction block for interconnecting insulated electrical leads and comprising an insulating body having an arcuate peripheral surface, first and second arcuate electrical terminals being slidably arranged on said peripheral surface in embracing relationship therewith and each being formed with a contact arm extending towards the contact arm of the other terminal and with a lead receiving opening communicating with a wire slot extending peripherally of said body, the terminals being slidable towards each other on said peripheral surface, from a first position in which the lead receiving opening of each terminal is in register with a lead receiving recess opening into said peripheral surface, and a second position in which said openings are out of register with said recesses and said contact arms are in electrically conductive contact with each other; whereby a lead inserted through each opening and thence into the groove in register therewith, in said first position of the terminals, is forced into the wire slot communicating with that opening, as the terminals are moved towards said second position, so that the edges of the wire slot pierce the insulation of the lead to make electrically conductive contact with the metal core of the lead.

2. A junction box as claimed in claim 1, wherein each said recess is in the form of a groove which extends from said peripheral surface across an end face of the insulating body.

3. A junction box as claimed in claim 1 or 2, wherein opposite end faces of the insulting body are formed with notches, having side walls which diverge towards said peripheral surface and intersect it, the notches being offset from one another circumferentially of said peripheral surface, each contact arm having a hole therein through which a tool can be inserted into one of said notches, in the first position of said terminals, and manipulated to drive them towards their second position.

4. A junction block as claimed in claim 1, 2 or 3, wherein the contact arm of one of the terminals has a contact beam underlying a contact surface of the other terminal in the second position of the terminals, the contact arm of the one terminal being depressible to disengage the contact beam from the contact surface of the other terminal.

5. A junction block as claimed in claim 4, wherein said body is of circular cross section and is formed with a radial rib defining the first position of said terminals, said peripheral surface being formed with a stop for engagement by said contact beam, which projects laterally from the contact arm of said one terminal, said stop defining the second position of said one terminal, a groove proximate to said stop allowing said contact beam to be depressed to disengage it from the contact arm of the other terminal.

6. A junction block as claimed in any one of the preceding claims, wherein said insulating body is encased between a pair of interengaging, insulating end plates each having a lead access opening in register with one of said recesses in the insulating body and a probe access opening in register with each terminal to allow the terminals to be moved from their first to their second position by means of a probe inserted through said probe access opening.

7. A junction block as claimed in claim 6, wherein an elastomeric seal surrounding said insulating body and being interposed between said end plates is formed with sealing grommets projecting therefrom in opposite senses, and being engaged in said access openings.

8. A junction block as claimed in claim 7,.wherein the grommets engaged in said probe access openings extend from anchoring portions of the seal, which are retained in complementary grooves in said end plates.

9. A junction block as claimed in any one of claims 6 to 8, wherein each end plate has a central circular opening for receiving an end portion of said insulating body and communicating with a groove in said end plate, said groove receiving a rib projecting radially of said arcuate surface and between ends of said terminals remote from the contact arms thereof.

10. A junction block assembly comprising a row of junction blocks as claimed in any one of claims 6 to 9, and a mounting rai having opposite, in-turned, longitudinal margins, each end plate having a pair of opposite mounting feet for slidable engagement beneath said margins, the junction blocks of the row being arranged in two groups on each side of junction block separating members projecting from the rail between the blocks of the two groups and between said margins, means for mounting the rail to a support, being provided between said separating members.

11. An electrical junction block for interconnecting insulated leads, substantially as hereinbefore described with reference to the accompanying drawings.

12. An assembly as claimed in claim 10, substantially as hereinbefore described with reference to the accompanying drawings.