WO1994013032A1

WO1994013032A1 - Sealed insulation displacement terminal block

Info

Publication number: WO1994013032A1
Application number: PCT/US1993/011741
Authority: WO
Inventors: Joseph D. Lorenzen; Antoon M. Hurkmans; Suresh Venkat
Original assignee: Communications Technology Corporation
Priority date: 1992-12-03
Filing date: 1993-12-03
Publication date: 1994-06-09
Also published as: MX9307660A; AU5738094A

Abstract

An environmentally sealed insulation displacing terminal block (20) comprising: a housing having an entry passage (52); stationery wire support means in the housing; insulation displacing contact means (10) in the housing; means (100) for moving the insulating displacing contact relative to the stationery wire support means in the housing to displace insulation and contact conductor supported by the wire support means; and a volume of encapsulant in the housing, the volume being sufficient to prevent entry of moisture through the entry passage, the insulation displacing contact means (10) being configured to permit substantially unobstructed flow of encapsulant around the insulation displacing contact means (10) upon movement of the insulation displacing contact means (10) through the housing.

Description

SEALED INSULATION DISPLACEMENT TERMINAL BLOCK

FIELD OF THE INVENTION The invention pertains to improved terminal units for providing access and connecting a service wire to a telecommunications distribution cable. An insulation displacing member, is movably mounted relative to the service wire to provide redundant connections to each service wire. The terminal units contain an encapsulating gel to insulate and environmentally protect the connection.

BACKGROUND OF TEE INVENTION Terminal blocks, used to connect service wires to a telecommunications distribution cable, are widely used in aerial, above ground pedestal, direct buried and underground enclosures. The enclosures provide some environmental protection, but they have not adequately protected the terminal connections against the full range of temperature, humidity, flooding, pollutants, and applied chemicals such as insecticides and herbicides. Further, gel-like insulating material, tends to squeeze out of the terminal unit and not seal properly if the terminal unit is re- entered.

Difficulty has been encountered in attempting to retain sealing material in a terminal block having insulation displacing terminals which are easily actuated without employing structure which is unduly complicated.

A typical terminal block is equipped with a stub cable and a plurality of terminal units. When the stub cable is spliced to a distribution cable, the terminal units provide access to the wires of the distribution cable. The terminal units are generally either the binding post type or insulation displacement type.

The binding post type terminal units are labor intensive to use because the service wires must be stripped of insulation prior to making the electrical connection. The insulation displacement type terminal units do not require prior stripping of the service wires and a standard 216 type tool (3/8 or 7/16 inch hex socket) may be used to make the connection. However, the volume of the chamber containing gel-like sealant usually changes when insulation displacement type terminals move through the terminal units leaving voids in the sealant.

Several different insulation displacement type terminal blocks incorporate terminals having sharp edged blades or jaws for cutting through insulation on the wire.

U.S. Patent No. 4,423,916 and U.S. Patent No. 4,428,634 disclose multiple piece connectors which include slotted contact elements configured to penetrate the wire insulation for making electrical contact with the wires of the cable.

U.S. Patent No. 4,029,384 discloses an electrical connector having blades coined to reduce the width of flared edges to facilitate penetration of insulation on an insulated conductor and ultimately contact the conductor wire. The blades are formed on a grounding clip and the insulated wire is pushed between the blades for displacing insulation and grounding the conductor in the insulated wire.

Tubular terminals having slots formed for piercing insulation by movement of an insulated wire through slots in the terminal are disclosed in U.S. Patent No. 3,897,128; U.S. Patent No. 4,141,618; U.S. Patent No. 4,261,633. U.S. Patent No. 4,767,354 and U.S. Patent No. 5,120,245.

Patent No. 4,971,573 discloses an internally threaded tubular contact having a cutting edge formed on the lower end. The tubular contact is rotated for moving the cutting edge into engagement with an insulated wire for cutting through the insulation on wire gripped between a pair of shoulders adjacent opposite sides of a groove formed in the connector body.

In an effort to form environmentally sealed terminal blocks, grease, gel or rubber material has been deposited in terminal blocks to prevent entry of water and other contaminants into the block to provide an environmental seal while attempting to prevent degrading the electrical contact between terminals and insulated wires. A paper entitled "AN ENVIRONMENTALLY SEALED TERMINAL BLOCK WITH ROTARY CONNECTION" published in the International Wire and Cable Symposium Proceedings. 1989, Pages 513-516, describes criteria for environmentally sealing a terminal block.

Other connector devices are disclosed in U.S.

Patent No. 3,850,497 U.S. Patent No. 3,897,128 U.S.

Patent No. 3,990,764 U.S. Patent No. 4,029,384 U.S.

Patent No. 4,070,548 U.S. Patent No. 4,141,618 U.S.

Patent No. 4,261,633 U.S. Patent No. 4,600,261 U.S.

Patent No. 4,634,207 U.S. Patent No. 4,767,354 U.S.

Patent No. 4,864,725 U.S. Patent No. 4,950,546 U.S. Patent No. 4,971,573; U.S. Patent No. 4,972,042 and U.S. Patent No. 5,140,746.

Attempts to develop environmentally sealed insulation displacement terminal blocks have resulted in structures that are unduly complicated and often tend to damage the conductors which results in unsatisfactory connections or splices. Further, the insulation displacement terminal blocks have not provided satisfactory environmental sealing.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved insulation displacement type terminal unit. The terminal unit connects an insulated service dropwire to a source wire. The invention provides a dual insulation displacing member so that the integrity of the electrical connection may be assured. The displacing member is movably mounted to engage the service wire that is anchored in a stationary position against a stop. The displacing member may be disengaged from the service wire so that the terminal unit is re-enterable and so that the source wire and the service wire can be isolated from each other and separately tested. The terminal unit generally comprises in combination: a body, a wiper bus contact, a source lead, a contact cover, an insulation displacing member, a contact, a movable block, and a gel dispersed within the body. The wiper, mounted in the body, has a conductive surface connected to a source electrical conductor, and the electrically conductive contact, in sliding engagement with the wiper bus contact, has first and second electrically conductive insulation displacing surfaces configured to pierce the insulation on the service dropwire conductor and make electrical contact with the service electrical conductor. The contact cover is adapted to receive an end of an insulated service electrical conductor and to position it to be engaged by the insulation displacing surfaces on the movable contact which is carried by a movable block.

The body environmentally and electrically insulates the electrical terminal connection. The wiper is secured within the body and provides an electrically conductive surface. The source lead electrically connects a source wire to the wiper.

The cover is supported by the body and is adapted to receive and engage the end of an insulated service wire. The movable block is located within the body and mounted to the cover. The displacing member and the contact are secured to the movable block. When the movable block is moved, the displacing member and the contact move relative to the cover. The displacing member and the contact also move relative to the body and the wiper because the cover is supported by the body.

The movable block is capable of moving the displacing member between a loading position, wherein the insulated end of the service electrical conductor is positioned adjacent the cover, in a displacing position, wherein the displacing member pierces the insulation on the insulated service wire. The displacing member is adapted to pierce the insulation on the service wire in at least two places to make at least two electrical connections with the service wire. The two electrical connections with the service wire are redundant to ensure good electrical contact.

The contact is electrically connected to the displacing member. The contact is adapted for electrically engaging the conductive surface of the wiper when the displacing member is moved into the displacing position whereby the electrical connection between the source wire and the service wire is completed. Dispersed within the body is an encapsulating gel to electrically and environmentally insulate the terminal connection.

BRIEF DESCRIPTION OF THE DRAWINGS Drawings of a preferred embodiment of the invention are annexed hereto so that the invention may be better and more fully understood, in which like references designate like parts throughout the various figures of the drawings: FIGURE 1 is a perspective view of a ten pair terminal block;

FIGURE 2 is a fragmentary exploded front elevational view of the terminal block;

FIGURE 3 is a fragmentary exploded end view; FIGURE 4 is a top plan view of a terminal block housing showing terminal units at various stages of assembly;

FIGURE 5 is a bottom elevational view of the terminal housing; FIGURE 6 is a top plan view of a contact cover;

FIGURE 7 is a front elevational view of the contact cover;

FIGURE 8 is a bottom plan view of the contact cover; FIGURE 9 is a cross-sectional view taken along line 9-9 of FIGURE 6;

FIGURE 10 is a cross-sectional view taken along line 10-10 of FIGURE 7;

FIGURE .11 is a cross-sectional view taken along line 11-11 of FIGURE 7; FIGURE 12 is a cross-sectional view taken along line 12-12 of FIGURE 8;

FIGURE 13 is a front elevational view of a bus contact; FIGURE 14 is a side elevational view thereof;

FIGURE 15 is a rear elevational view;

FIGURE 16 is a cross-sectional view taken along line 16-16 of FIGURE 13;

FIGURE 17 is a front elevational view of an insulation displacing contact;

FIGURE 18 is a side elevational view thereof;

FIGURE 19 is a top plan view thereof;

FIGURE 20 is a top plan view of a contact base;

FIGURE 21 is a bottom elevational view thereof; FIGURE 22 is a side elevational view thereof;

FIGURE 23 is an end view of the contact base;

FIGURE 24 is a cross-sectional view taken along line 24-24 of FIGURE 22;

FIGURE 25 is a cross-sectional view taken along line 25-25 of FIGURE 3, the contact base and the insulation displacing contact being illustrated in the lowered position;

FIGURE 26 is a cross-sectional view taken along line 26-26 of FIGURE 25, the contact base and the insulation displacing contact being illustrated in the lowered position;

FIGURE 27 is a cross-sectional view similar to FIGURE 25, the contact base and insulation displacing contact being illustrated in the elevated position; FIGURE 28 is a cross-sectional view similar to

FIGURE 26, taken along line 28-28 of FIGURE 27, the contact base and the insulation displacing contact being illustrated in the elevated position; and

FIGURE 29 is an enlarged fragmentary plan view of a terminal housing. Numeral references designate like parts throughout the various figures of the drawings.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGURE 1 of the drawing, the numeral

10 generally designates a terminal block formed by a terminal housing 20 having a plurality of terminal units 20a—20j, each terminal unit being closed by a contact cover 50. As will be hereinafter more fully explained, each terminal unit has two pair of dropline passages, a first pair 60T and 60R and a second pair 62T and 62R. One of the passages of each pair of passages is adapted to receive the tip conductor 12T or 13T and the other to receive the ring conductor 12R or 13R of a pair 12 or 13 of dropwire conductors. The terminal units 20a—20j should be adequately spaced and oriented to facilitate efficient connection of the largest service wires the terminal units are designed to accommodate. Terminal units normally are designed to accommodate up to 18 gauge "F" drop wire (copper coated steel) .

Terminal block 20 is adapted for connecting a plurality of conductor pairs which extend through an insulated cable 11 to tip and ring conductors in a plurality of droplines. The particular embodiment of the insulation displacement terminal 10 illustrated in the drawing is a ten pair terraced housing having two rows of terminal units.

The terminal units 20a-20j are preferably of the insulation displacement type. The service dropwire pairs 12 and 13 do not have to be stripped prior to making the connection to the terminal units. In the preferred embodiment of the present invention, a standard 216 type tool (3/8 or 7/16 inch hex socket) may be used to accomplish the connection. Referring to FIGURES 1 and 4 of the drawing, it should be noted that terminal units 20a—2Oe are arranged in a first row and terminal units 20f—20j are arranged in a second row. It will be appreciated that terminal unit 20a is spaced substantially midway between terminal units 2Of and 20g to facilitate connecting conductor pairs to the respective terminal units since a pair of conductors inserted in tip and ring passages 60T and 60R in terminal unit 20a will extend substantially midway between terminal units 2Of and 20g and conductor pairs associated therewith.

Re erring to FIGURES 1 and 3, it should be noted that terminal units 20a—2Oe of the first row of terminal units are elevated vertically relative to terminal units 2Of—20j of the second row of terminal units, if tip and ring passages are to be accessed from one side of the terminal block. However, it is contemplated that for some applications terminal units 20a—20e may be mounted back-to-back with terminal units 2Of—20j such that tip and ring passages into terminal units in the first row are accessible from one side of the block while tip and ring passages in terminal units 2Of—20j in the second row would be accessible from the opposite side of the terminal block 10.

If the first and second rows of terminal blocks are arranged back-to-back to provide access to tip and ring passages from opposite sides of the terminal block, the first and second rows of terminal units may be mounted such that upper surfaces thereof lie in a common plane to reduce the height of the terminal block. Further, terminal units 20a and 2Of may be mounted back-to-back to shorten the overall length of the terminal block. Terminal units 20a—20j are preferably of substantially identical construction though the position and orientation of one terminal unit 20a may vary relative to other terminal units 20f and 20g depending upon the particular application.

If terminal block 10 is to be mounted in an aerial enclosure, for example, of the type disclosed in U.S. Patent No. 4,721,830, the first and second rows of terminal units would preferably be terraced to provide access to each terminal unit from one side of the terminal block. However, if the terminal block is to be mounted in an enclosure on a post, pedestal or wall where access is unlimited on each side of the terminal block, the terminal units may be mounted back-to-back as hereinbefore described. Further, terraced terminal blocks 10 may be mounted back-to- back, if it is deemed expedient to do so to provide access to two rows of terminal units from one side and two rows from the opposite side of the terminal block. As best illustrated in FIGURES 1, 4 and 5 of the drawing, one end of housing 20 has an upturned groove 18 formed therein and the opposite end has a downwardly extending tongue 16 which mate with complementary surfaces on endcaps 17 and 19 which extend across space adjacent opposite ends of terminal block 10 between front wall 22 and rear wall 24 to form a cavity 15 below bottom walls 30 into which potting material may be deposited for forming a strong rigid waterproof base after the components of the terminal block have been assembled.

If a plurality of terminal blocks 10 are to be connected as a unit, for example for connecting a five pair block with a ten pair block to provide a fifteen pair block, the downwardly extending tongue 16 on one end of housing 20 will be positioned in the upwardly facing groove 18 on the end of an adjacent block such that the blocks are locked together. As viewed in FIGURE 5 of the drawing, it will be noted that one of the rows of terminal units 20a—2Oe is shifted laterally relative to terminal units 20f—20j of the second row to form a stepped configuration adjacent opposite ends of housing 20. Downwardly projecting tongue 16 is formed by legs 16a, 16b and 16c which are not in alignment. When tongue 16 is positioned in a similarly shaped groove 18, the adjacent terminal blocks 10 are locked together to prevent movement of the blocks relative to each other in any direction in the plane of the base of the terminal housing 20.

As best illustrated in FIGURE 5 of the drawing, a pair of spaced cylindrical bosses 14 extend downwardly from the bottom wall of terminal housing 20 and have holes 14a formed therein to receive the threaded end of a self-tapping anchor bolt (not shown) for mounting the terminal block on any suitable support surface. A pair of clips 21 project downwardly from the bottom wall 30 for attaching an organizer sleeve formed by a substantially cylindrical member having a slot formed in one side thereof and laterally projecting ears which snap onto clips 21 to provide an entry port for a stub cable 11 into the housing.

Terminal housing 20 is preferably molded of a non-conductive material such as ABS and preferably is of unitary construction. It should be appreciated that any number of terminal units may be incorporated into a single terminal block or that multiple terminal blocks 20 may be used in combination to accommodate any number of pairs of conductors.

Referring to FIGURES 2, 4, 25, 26 and 29 of the drawing, each terminal unit 20a—20j in the illustrated embodiment has a front wall 22, rear wall 24 and a pair of side walls 26 and 28 forming a generally rectangular shaped chamber 25 having a bottom wall 30. The front wall 22 of each terminal unit 20a—20j has a notch 35 bounded by surfaces 35a, 35b and 35c, surface 35b intersecting with inclined surfaces 35a and 35c, as illustrated in FIGURE 2 of the drawing.

Rear wall 24 and side walls 26 and 28 have an upwardly extending rib 32 extending around the periphery thereof. Rib 32 also extends along surfaces 35a, 35b and 35c to form a rib that extends around substantially the entire periphery of upper edges of the front wall 22, rear wall 24 and side walls 26 and 28 to facilitate attaching a contact cover 50 over chamber 25 as will be hereinafter more fully explained.

As illustrated in FIGURES 4, 5, 25, 26 and 29, a cylindrical cup 31 bounded by a cylindrical sidewall 31a and a bottom wall 31b is formed in bottom wall 30. A tapered substantially cylindrical post 33 extends upwardly from the bottom of cup 31 to form a guide for a movable insulation displacing assembly formed by movable contacts 80 carried by a platform 90, as will be hereinafter more fully explained.

A partition wall 40, best illustrated in FIGURES 4, 26 and 29, extends across a portion of the interior of chamber 25 and has opposite ends connected to rear wall 24 by spacers 42 and 44. A center wall 45 joins a central portion of partition wall 40 with rear wall 24 to form a pair of generally rectangular shaped passages 46 and 48 adjacent opposite sides of center wall 45. Passages 46 and 48 extend vertically between partition wall 40 and rear wall 24. As best illustrated in FIGURES 26 and 29, upper ends of spacers 42 and 44 and center wall 45 have surfaces 42a, 44a and 45a inclined downwardly toward rear wall 24. Seats 41 are formed in the upper edge of partition wall 40 adjacent passages 46 and 48 to provide a relatively narrow support surface for a bridge portion 71 of a bus contact 70, illustrated in FIGURES 3, 14, 26 and 28, as will be hereinafter more fully explained.

A pair of openings 47 and 49 is formed in bottom wall 30 adjacent partition wall 40. Shoulders 47a and 49a project upwardly from bottom wall 30 adjacent openings 47 and 49 for receiving connector lugs 78 on ends of a bus contacts 70,. as will be hereinafter more fully explained.

Spaced rails 27 extend vertically along front wall 22 of each terminal unit. As will be hereinafter more fully explained, rails 27 provide a pair of elongated vertical guide surfaces 27a that extend upwardly from bottom wall 30 adjacent opposite ends of front wall 22 into chamber 25 and a pair of guide members 29 provide a pair of elongated vertical guide surfaces 29a that extend upwardly from bottom wall 30 adjacent side walls 26 and 28 and adjacent opposite ends of partition wall 40.

Referring to FIGURES 2, 3 and 6-12 of the drawing, the numeral 50 generally designates a contact cover having a central opening 52 extending ( therethrough. A narrow bead 53 projects into opening 52 to engage threads on the shank 105 of an anchor screw 100 to provide a seal to prevent leakage of uncured encapsulant gel when chamber 25 is filled. A raised shoulder 56, having a shallow cylindrical socket 54, is formed on the upper surface of contact cover 50 around the central opening 52 to engage the lower surface on the head 102 of threaded screw 100 to provide a second seal for retaining gel in chamber 25. Referring to FIGURES 2, 7 and 8 of the drawing, it should be noted that contact cover 50 has a groove 32' extending around the periphery thereof configured to receive the rib 32 which extends around upper edges of the walls 22, 24, 26 and 28 of the terminal units 20a—20j. As best illustrated in FIGURE 7, the front face 55 of contact cover 50 is shaped to be received in notch 35 formed in the front wall 22 of housing 10. A pair of passages 60T and 60R is formed in contact cover 50 and are adapted to receive tip and ring conductors of a pair of conductors. A pair of smaller passages 62T and 62R is formed in face 55 of contact cover 50 for receiving the tip and ring conductors of a pair of small gauge conductors. Passages 60T and 60R extend into the body of contact cover 50 and have ends blocked by a stop 61 projecting across the ends of openings 60T and 60R. As best illustrated in FIGURES 9 and 10 of the drawing, each passage 60T and 6OR has upper cylindrical surfaces 60a, 60b and 60c separated by slots 68 and 69 which receive insulation displacement contacts as will be hereinafter more fully explained.

Referring to FIGURES 9 and 11 of the drawing, passages 62T and 62R extend through the body of contact cover 50 and have upper surfaces 62a, 62b and 62c separated by slots 68 and 69.

As illustrated in FIGURES 8, 9 and 25, the lower surface of contact cover 50 has a pair of spaced cylindrical sockets 58 formed therein which extend almost through the upper surface of contact cover 50. However, upper ends of sockets 58 are closed by a thin layer 59 which is configured to be broken or pierced by an insulation displacing assembly as will be hereinafter more fully explained to provide visual confirmation that insulation displacement contacts 80, illustrated in FIGURES 2, 3, 17-19, and 25-28, have been moved to engage the service dropwires.

As best illustrated in FIGURES 1, 6, 26, 28 and 29 of the drawing, a pair of test ports 64 and 66 is formed in an upwardly extending boss 65 formed on cover 50 above passages 46 and 48 in the housing body 20. Walls 63 and 67 of the boss 65 are offset, as illustrated in FIGURES 1 and 6, to prevent contact between a pair of test clips (not shown) when inserted into the test ports 64 and 66, as will be hereinafter more fully explained.

A longitudinally extending partition wall 40 extends upwardly from bottom wall 30 and has opposite ends terminating inwardly from side walls 26 and 28. Center wall 45 extends between a central portion of partition wall 40 and rear wall 24 to stabilize the partition wall 40 and to prevent electrical shorting between bus contacts 70 in passages 46 and 48.

A bus contact 70 is best illustrated in FIGURES 2, 3 and 13-16 of the drawing. The lower portion of bus contact 70 has a central body portion 72 and a pair of outwardly deflected wiper surfaces 74 on the ends of outwardly deflected spring leg members 76.

As illustrated in FIGURE 14, the central portion of bus contact 70 is deflected laterally from the plane of the body portion 72 to form a bridge portion 71 between the upper end of body portion 72 and the lower end of a twisted test lead portion 73. The upper edge 73a of test lead 73 is rotated about 45° relative to the plane of body portion 72 of bus contact 70. A connector lug 78 is formed on the lower end of body portion 72 and is positionable through opening 47 or 49 formed in the bottom wall 30 of each terminal unit in terminal housing 20. The rear surface 72a on body portion 72 is configured to engage partition wall 40 when bridge portion 71 of bus contact 70 is positioned in seat 41 formed in the upper edge of partition wall 40. As illustrated in FIGURE 26 of the drawing, a stub conductor 11R is mounted on connector lug 78 on bus contact 70 and soldered, wire wrapped or otherwise joined to prevent disconnection.

Insulation displacing contacts 80 are illustrated in FIGURES 2, 3 and 17-19 of the drawing. As best illustrated in FIGURES 17 and 18, each insulation displacement contact has a pair of blades 81 and 82 having a ledge portion 84 extending between lower ends thereof. The ledge portion 84 has a central opening 83 and a generally crescent-shaped socket 85 formed therein. Each of the blades 81 and 82 has a pair of sharp edged slots 86 and 88 formed therein.

Referring to FIGURES 25-28 of the drawing, the large slots 86 are aligned below passages 60T and 60R while the smaller slots 88 are vertically aligned below passages 2T and 62R.

Spring elements 87 and 89, best illustrated in FIGURES 26 and 28, are formed on edges of ledge portion 84 of insulation displacement contact 80 for maintaining contact 80 in engagement with one of the wiper surfaces 74 on bus contact 70. Spring element 87 rides along the face of rib 23 on the inside of the front wall 22 of a terminal housing unit in the terminal housing 20 while spring element 89 is resiliently urged into sliding engagement with one of the wiper surfaces 74 on bus contact 70.

A pair of insulation displacement contacts 80 is carried on a movable platform 90, illustrated in FIGURES 2, 3 and 20-24 of the drawing. The platform 90, preferably molded of for example 15% glass filled polyester, has a resilient central body portion 92 through which passage 93 extends. A pair of stanchions 94 project upwardly from the upper surface of the body portion 92.

A sleeve 95 extends downwardly from body portion 92 and a pair of slots 96 are formed in edges thereof. A generally cylindrical sleeve portion 95a and a pair of projections 97 connect the upper and lower portions of the central body portion 92.

Referring to FIGURES 2 and 25, the central ledge portion 84 of insulation displacement contact 80 slides into a slot 96 on platform 90 such that the crescent shaped socket 85 partially encircles the upper sleeve portion 95a for stabilizing insulation displacement contact 80. If it is deemed expedient to do so, rivets may be positioned through holes 98 in platform 90 and through openings 83 in insulation displacement contacts 80 for securing the contacts relative to platform 90.

A pair of shoulders 91 are formed on opposite ends of the upper portion of the body 92 of platform 90 and move adjacent side walls 26 and 28 for preventing lateral motion of platform 90 and insulation displacement contacts 80 as they move vertically through chamber 25. Shoulders 91 project downwardly across the entrance into slots 96 and snap into engagement with the rear edge of ledge portion 84 of insulation displacing contact 80. A spring wavey washer 99, best illustrated in

FIGURES 2, 3 and 25-28, having a central aperture 99a, and a pair of O-rings 97 drop over post 33 which extends upwardly from the bottom 31b of the cylindrical cup 31 extending downwardly from bottom wall 30 of each terminal housing 20. Spring 99 and o- rings 97 urge platform 90 upwardly when sleeve 95 moves into cup 31. O-rings 97 capture the wavey washer 99 during the assembly process and in addition resiliently urge platform 90 upwardly. A threaded actuator screw 100, having a head 102 and a flange 104 extending thereabout, has a threaded shank 105. Shank 105 extends through opening 52 formed in contact cover 50 and its lower end is threadedly secured in the passage 93 formed in platform 90. Rotation of threaded shank 105 moves platform 90 vertically from the position illustrated in FIGURE 25 of the drawing to the position illustrated in FIGURE 27.

Stanchions 94 adjacent opposite ends of platform 90 extend into sockets 58 in contact cover 50 while post 33, extending upwardly from the bottom of cup 31, extends into the lower end of opening 93 in platform 90. Shoulders 91 adjacent opposite ends of platform 90 move adjacent the inner surfaces of side walls 26 and 28 while spring elements 87 and 89 move along surfaces of ribs 23 and wiper surfaces 74.

A screw retainer 110, best illustrated in FIGURES 1, 2 and 3 has a central opening through which head 102 of screw 100 extends. Flange 104 is captured in a pocket formed in the lower surface of retainer 110. Referring to FIGURES 2, 3, 6, and 11 screw retainer 110 has pegs 111 which extend into sockets 51 formed in the upper surface of contact cover 50. After actuator screw 100 is properly positioned through opening 52 in contact cover 50, screw retainer 110 is ultrasonically welded or otherwise bonded to cover 50.

Indicia "T" and "R" along with a numeric designation is provided on each screw retainer 110 to aid a technician in the field. When conductors are positioned through passages 60T and 6OR as illustrated in FIGURES 1 and 26 of the drawing, the end of the conductor engages stop 61 to assure that the wire is properly positioned. Rotation of screw 100 moves platform 90 and insulation displacement contacts 80 vertically to the position illustrated in FIGURE 28 of the drawing. It should be appreciated that the upper surface of the wire 12R engages surfaces 60a, 60b and 60c preventing vertical movement of the wire as insulation displacement contacts 80 move toward the position illustrated in FIGURE 23. Knife edges on blades 81 and 82 pierce the insulating layer on the dropwire and engage the metallic conductor 12R* for making an electrical contact.

The upper surface of the body portion 92 of platform 90 engages surface 60f on the bottom of cover 50 to limit upward movement of contacts 80 to prevent inadvertent cutting of conductor 12R' which could occur if the range of movement of contact 80 were unlimited.

The upper ends 94a of stanchions 94 pierce the layer 59, illustrated in FIGURE 25, which closes the upper ends of sockets 58, to provide a visual indication, as illustrated in FIGURES 27 and 28, that platform 90 and insulation displacement contacts 80 have been moved to the elevated position. If the ends 94a of "tell-tale" indicator tab stanchions 94 do not project through cover 50, the technician knows that the electrical connection is not complete.

The provision of two insulation piercing blades 81 and 82 on each contact 80 provides redundant connections between the contact 80 and the electrical conductor 12R* . In addition, the multiple blades 81 and 82 provide a strong gripping action to keep the wire from being pulled out of the terminal after platform 90 has been moved to the elevated position.

A contact cover 50 is positioned over each terminal housing 20 after bus contacts 70 have been installed in chamber 25 such that connector lugs 78 extend through openings 47 and 49 in the bottom wall 30 of the terminal housing 20. Test lead portions 73 of each bus contact 70 extends through a passage 64 or 66 in the raised boss portion 65 of contact cover 50. The rib 32 extending around the periphery of upper edges of the walls of terminal housing 20 extend into grooves 32' which extend around the periphery of contact cover 50 and the cover 50 is preferably ultrasonically welded or otherwise bonded or glued in place.

From the foregoing, it should be readily apparent that the terminal housing 20 is generally adapted to receive and support the other elements of the terminal block 10. The housing 20 also is adapted to contain a volume of insulating encapsulant gel (not shown) . The terminal connections may be individually protected against environmental attack with encapsulant gels, such as those available from CasChe , Inc. of Bayonne, New Jersey under the trademark "BAKER, BUFFERITE GELS", product designation "BUFF 117M2"; Ciba-Geigy; Dow Corning under the trademark "SYLGARD", 527 Primerless Silicone Dielectric Gel; Raychem Corporation and Western Electric. Various gels are adequate, but preferably the insulating gel has a cone penetration value in the range of about 35 X 10^*1 millimeters to aoout 50 X 10^"1 millimeters, tensile strength in the range of about 1 p.s.i. (pound per square inch) to about 5 p.s.i., and low ultimate elongation, less than about 20%. The commercially available gel marketed under the trademark "SYLGARD", 527 Primerless Silicone Dielectric Gel, by Dow-Corning has all of these physical properties. The low cone penetration value range means that the gel is easy to penetrate by service wires over a wide range of temperatures. The low tensile strength means that the gel tends to adhere to the service wires. The low percent elongation means that the gel is unlikely to tear and it is more likely to mold or form itself around the service wires that are inserted into the gel.

The gel is preferably cohesive. The cross-linked polymer chains of the gel cannot move freely relative to each other. Therefore, the gel is deformable and has memory. The gel tends to return to the shape in which it was cured, which makes it ideal for repeated re-entry into the terminal unit.

The gel also is preferably moderately adhesive. When a service wire is inserted into the terminal unit, the encapsulating gel adheres to the surfaces of the wire and displaces water and other fluids. When the insulation displacing contact 80 engages the service wire, the gel is displaced from between the blades 81 and 82 of contact 80 and the service wire.

The gel can also protect the electrical connections from thermo-mechanical and mechanical shocks and vibrations. The gel preferably has physical and electrical stability from minus 50°C to 200°C, and the gel has excellent dielectric properties even at the upper end of this temperature range.

The gel is preferably highly hydrophobic and has excellent chemical and weathering resistance. Rain, cold, heat, ultra-violet radiation, ozone, long-term exposure to atmospheric pollutants, and organic chemicals have no effect on the gel. The gel does not harden, crack, peel, crumble, dry-out, liquify, rot, or become brittle over time.

Digital communications are sensitive to the electrical noise interferences in telecommunications networks. Much effort has been expended to stabilize the electrical characteristics of telecommunications networks. The terminal block connections, however, are particularly susceptible to environmental conditions because of the need for easy access to the distribution cable. Cyclic temperature changes, humidity, flooding, pollutants, chemicals, vibrations, and stresses contribute to chronic and acute loss of electrical integrity and connection deterioration. It should be appreciated that as platform 90 and blades 81 and 82 on insulation displacing contacts 80 move vertically through chamber 25, the volume of the chamber does not change. An encapsulant gel in chamber 25 flows from above platform 90 into space below platform 90 as the platform is moved through the chamber. Shoulders 91 on opposite ends of platform 90 space the platform 90 from side walls 26 and 28 while spring elements 87 and 89 bridge the gaps between front and rear edges of platform 90 and front wall 22 and partition wall 40. Ribs 23, rails 27 and guide surfaces 29 maintain the platform centered in chamber 25 to assure adequate space around the edges thereof to permit substantially unobstructed flow of gel around platform 90 as it moves vertically through chamber 25.

Further, passages 46 and 48 as well as test ports 64 and 66 are filled with encapsulant gel. In addition, open columns 36 are available for encapsulant gel adjacent rear corners of chamber 25. Thus, a reservoir having a volume equal to approximately 25% of the volume of chamber 25 is provided to assure that an adequate volume of encapsulant gel is maintained to prevent formation of voids in chamber 25 as platform 90 moves therethrough. Gel flows in the opposite direction if platform 90 and contacts 30 are moved downwardly to remove or replace service wires.

The metal conductor 12R' in the service wire is gripped at two locations by blades 81 and 82 on the metallic insulation displacement contact 80. Metallic spring element 89 on insulation displacement contact 80 moves in wiping engagement with wiper surface 74 on bus contact 70 having the metallic stub conductor 11T or 11R in source line 11 firmly secured thereto. Thus, there is metal-to-metal contact between conductor 12R¹ and insulation displacement contact 80, between insulation displacement contact 80 and bus contact 70, and between the bus contact 70 and the stub conductor 11R¹ in source line 11 completing an electrical circuit from stub source line 11 to service line dropwire conductor 12R' . The slight pressure differential formed across platform 90 as it moves vertically through chamber 25 induces a flow of sealant around platform 90 to assure that no voids or air bubbles are formed in the sealant to prevent ingress of water, air or other potentially corrosive substances.

As hereinbefore described, the connector lugs or source leads 78 of the bus contacts 70 are inserted into openings 47 and 49. Conductor wires 11T and 11R of each stub conductor pair 11 are connected by soldering, wire wrapping, or any other suitable method to connector lugs 78 of each bus contact 70 to withstand extreme temperature cycling from 25 °F to minus 40°F. To protect the connections between the connector lugs 78 and stub conductor wires 11, an uncured liquid potting material is poured into cavity 15 over the connections and cured in place. The connections are thereby totally and permanently environmentally sealed and a bottom wall to the housing body 20 is formed.

After the cover 50 has been assembled with the actuator screw 100 extending through central opening 52 and held in position by screw retainer 110; a platform 90, carrying two movable contacts 80 in grooves 96, is mounted on the threaded shank 105 of actuator screw 100.

After spring wavey washers 99 and a pair of resilient O-rings 97 have been positioned on posts 33 in cups 31, platforms 90 are positioned in terminal units 20a - 20j. The cover 50 is secured in position on each terminal unit and the cover 50 is welded or otherwise bonded in place.

The encapsulating gel is then introduced into the assembled terminal unit 20.

Other encapsulants are disclosed in U.S. Patent No. 997,066; U.S. Patent No. 4,070,543; and U.S. Patent No. 5,140,746.

If the gel is delivered through a dispenser (not shown) into open columns 36 and passages 46 and 48, dropwire passages 60T, 60R, 62T and 62R and test ports 64 and 66 are preferably closed by tape while the gel cures in chamber 25. If gel is delivered through dropwire passages 60T and 60R; columns 35, passages 46 and 48 and test ports 64 and 66 would be sealed at least until the gel cures.

Reasonable variations can be made in view of the foregoing disclosure without departing from the spirit or scope of the present invention.

Claims

We claim:

1. A terminal block for connecting a pair of dropwire conductors to a pair of stub conductors comprising: a terminal unit, said terminal unit having a pair of passages for receiving the dropwire conductors and for positioning said dropwire conductors in said terminal unit; a pair of bus contacts having wiper sur aces in said terminal unit, said bus contacts having connector lugs connectable to the stub conductors; a pair of movable contacts mounted for movement in said terminal unit, said movable contacts having surfaces engaging said wiper surfaces; and an actuator connected to said movable contacts, said actuator being accessible from outside said terminal unit for moving said movable contacts into and out of engagement with said dropwire conductors for completing or breaking an electrical circuit between said stub conductors and said dropwire conductors.

2. A terminal block according to Claim l, each of said contacts of said pair of movable contacts comprising: a blade having a slot bounded by surfaces which engage one of said dropwire conductors.

3. A terminal block according to Claim 1, each movable contact of said pa r of movable contacts comprising: a pair of spaced blades, each of said blades having a slot formed therein bounded by surfaces which grip a dropwire conductor for establisning redundant points of contact between said movable contact and said dropwire conductor.

4. A terminal block according to Claim 3, each of said blades having a pair of slots formed therein, one of said slots being wider than the other slot for gripping dropwire conductors of different diameters.

5. A terminal block according to Claim l, said actuator comprising: a screw having a head accessible from outside the terminal unit.

6. A terminal block according to claim 1, with the addition of indicia on said terminal unit adjacent each passage of said pair of passages.

7. A terminal block according to Claim l, said terminal unit having a pair of test ports, one of said bus contacts of said pair of bus contacts having a test lead portion extending into one of said test ports.

8. A terminal block according to Claim 1, with the addition of: an encapsulant in said terminal unit, said encapsulant being adapted to environmentally seal each passage of said pair of passages.

9. A terminal block according to Claim 8, said encapsulant comprising: a silicon gel compound that forms a water-tight seal around each dropwire conductor for eliminating moisture and insect intrusion into said terminal unit.

10. A terminal block according to Claim 1, each contact of said pair of movable contacts comprising: a pair of blades adapted to provide two discrete connections with each of said dropwire conductors.

11. A terminal block according to Claim 1, with the addition of: platform means in said terminal unit, each contact of said pair of movable contacts being carried on said platform, said platform being connected to said actuator for moving each of said movable contacts into engagement with a dropwire conductor in one of said passages.

12. A terminal block according to Claim 11, said platform means having a pair of slots and a shoulder adjacent each of said slots, a portion of each of said contacts projecting into one of said slots and being retained in said slot by said shoulder.

13. A terminal block according to Claim 11, said platform means having an indicator for providing visual indication when said movable contacts engage a dropwire conductor.

14. A terminal block according to Claim 11, with the addition of: spring means urging said movable contacts into engagement with said bus contacts.

15. A terminal block according to Claim 1, with the addition of: means for connecting a plurality of terminal blocks together for connecting a plurality of pairs of dropwire conductors to a plurality of pairs of stub conductors.

16. A terminal block according to Claim 1, further comprising: an insulating gel dispersed within the terminal, said gel having a cone penetration value in the range of about 35 X 10^"1 millimeters to about 100 X 10^"1 millimeters; tensile strength in the range of about 1 p.s.i. to about 5 p.s.i.; and low ultimate elongation.

17. An insulation displacement terminal block for telecommunications dropwire conductors enclosed in insulation comprising: anchor means adapted to engage an end of an insulated electrical conductor; bus contact means; means securing said bus contact means relative to said anchor means; insulation displacement means having an electrically conductive surface configured to pierce insulation on an electrical conductor; means movably securing said insulation displacement means relative to said anchor means, said insulation displacement means being movable between a loading position wherein an insulated conductor is positionable adjacent said anchor means and an insula¬ tion displacement position wherein said conductive surface engages the electrical conductor; and a wiper surface on said bus contact means engaging said insulation displacement means when said insulation displacement means is in said insulation displacement position.

18. An environmentally sealed insulation displacing terminal block comprising: a housing having an entry passage; stationery wire support means in said housing; insulation displacing contact means in said housing; means for moving said insulating displacing contact relative to said stationery wire support means in said housing to displace insulation and contact conductor supported by said wire support means; and a volume of encapsulant in said housing, said volume being sufficient to prevent entry of moisture through said entry passage, said insulation displacing contact means being configured to permit substantially unobstructed flow of encapsulant around said insulation displacing contact means upon movement of said insulation displacing contact means through said housing.

19. An insulation displacement type terminal for an electrical connector comprising: a body; a wiper having a conductive surface, said wiper being secured to said body; a cover adapted to receive an end of an insulated electrical conductor, said cover being supported by said body; displacing means having a conductive surface configured to pierce insulation on an electrical conductor; contact means having a conductive surface electrically connected to said displacing means; a movable' block securing said displacing means and said contact means relative to said cover, said displacing means being movable between a loading position wherein an insulated conductor is positionable adjacent said cover and a displacing position wherein said conductive surface of said displacing means engages the electrical conductor and pierces the insulation of the electrical conductor; .and wherein said contact means electrically engages said wiper when said displacing means is in the displacing position.

20. The insulation displacement type terminal unit of claim 19 wherein said displacing means further comprises: a first displacing means and a second displacing means so that said first displacing means and said second displacing means make an electrical connection with the electrical conductor in two places.

21. The insulation displacement type terminal unit of claim 19 adapted to engage a pair of electrical conductors.

22. A terminal block according to Claim 21 further comprising: an insulating gel dispersed within the terminal, said gel having a cone penetration value in the range of about 35 X 10^"1 millimeters to about 100 X 10^'1 millimeters; tensile strength in the range of about 1 p.s.i. to about 5 p.s.i.; and low ultimate elongation.

23. An insulation displacement type terminal unit for connecting an insulated service electrical conductor to a source electrical conductor, said unit comprising: a body for environmentally and electrically insulating an electrical terminal connection; a wiper for providing an electrical contact surface, said wiper being supported within said body; a source lead for electrically connecting a source electrical conductor to said wiper; a cover for receiving an end of an insulated service electrical conductor, said cover being supported by said body; displacing means for displacing the insulation on the service electrical conductor in at least two places and making at least two electrical connections with the service electrical conductor; contact means for electrically engaging said wiper, said contact means being electrically connected to said displacing means; a movable platform for securing said displacing means and said contact means relative to said cover, said displacing means being movable between a loading position wherein the insulated end of the service electrical conductor is positionable adjacent said cover and a displacing position wherein said displacing means displaces the insulation on the insulated service electrical conductor in at least two places and makes electrical contact with the conductor of the service electrical conductor in at least two places; wherein said contact means electrically engages said wiper when said displacing means is in the displacing position.

24. The insulation displacement type terminal unit of claim 23 further comprising: a test lead for electrically connecting a test clip to said wiper; and an access port for providing access for the test clip to said test lead.

25. The insulation displacement terminal unit of claim 23 wherein the unit is further adapted to make an electrical connection between a pair of insulated service electrical conductors and a pair of source electrical conductors.

26. The insulation displacement terminal unit of claim 23 wherein the unit is further adapted to make an electrical connection of at least two different sizes of insulated service electrical conductor to the source electrical conductor.

27. The insulation displacement terminal unit of claim 23 wherein said displacing means has two different sizes of displacement members for making an electrical connection with at least two different sizes of electrical conductors.

28. An insulation displacement type terminal unit for connecting an insulated service wire to a source lead comprising: a body formed of an electrically insulating material adapted to environmentally and electrically insulate an electrical terminal connection; a wiper formed of an electrically conducting material, said wiper being supported by said body; a source lead formed of an electrically conducting material electrically connected to said wiper; a cover formed of an electrically insulating material supported by said body and adapted to engage an end of an insulated service wire; a first insulation displacing contact means having a conductive surface configured to pierce the insulation on the service wire and make electrical contact with the service wire; a second insulation displacing contact means having a conductive surface configured to pierce the insulation on the source electrical conductor and make electrical contact with the service wire; resilient contact means having an electrically conductive surface, said resilient contact means being electrically connected to said first and second insulation displacing contact means; actuator means movably securing said first and second insulation displacing contact means relative to said cover, said actuator means being movable between a loading position wherein the service wire is positionable adjacent to said cover and an insulation displacing position wherein both said first and second insulation displacing contact means pierce the insulation on the service wire and electrically engage the service wire; and indicator means associated with said actuator means for indicating when said actuator means has moved said first and second insulation displacing contact means to pierce the insulation on the service wire.

29. The insulation displacement terminal of claim 28 further comprising: an insulating gel dispersed within the terminal, said gel having a cone penetration value in the range of about 35 X 10^*1 millimeters to about 100 X 10^*1 millimeters; tensile strength in the range of about 1 p.s.i. to about 5 p.s.i.; and low ultimate elongation.