WO1998049751A1

WO1998049751A1 - Electrical connector with resilient insulation piercing terminals

Info

Publication number: WO1998049751A1
Application number: PCT/US1998/007938
Authority: WO
Inventors: Joannes W. M. Roosdorp; Vagner Fuzetti
Original assignee: The Whitaker Corporation
Priority date: 1997-04-30
Filing date: 1998-04-23
Publication date: 1998-11-05
Also published as: AU7139498A; BR9701976A

Abstract

A resilient terminal (14) is mounted in a nonconductive housing (12) to form an electrical connector (10) for terminating wires (2, 6). The terminals include insulating piercing teeth (28) at opposite ends and opposed terminals (14) are mounted in opposed housing (12) with the teeth (28) aligned with the wires (2, 6) to be terminated or spliced and located at the free end of spring beams (30) of the terminals. The terminal spring beams (30) are spring biased relative to the housing (12) through the bottom surface (28) of the housing slots (24). Overstressing of the terminal spring beams (30) is prevented because the spring beams (30) bottom against the slot bottom surface (28) or against other portions of the terminal (14) that engage the bottom surface (28).

Description

ELECTRICAL CONNECTOR WITH RESILIENT INSULATION PIERCING TERMINALS

This invention is related to an electrical connector and a terminal for establishing an electrical contact with one or more wires or conductors in which the electrical connection is made without stripping the insulation before establishing an electrical contact. An insulation piercing contact is used and this invention is primarily intended for use in a tap connector. This invention is also related to establishing a resilient electrical and mechanical contact with stranded wires.

Insulation displacement contacts are commonly used to tap or otherwise connect insulated wires without the need to strip the insulation from wires. Insulation displacement terminations are one form of insulation penetrating contacts. With insulation displacement contact, opposed edges of a slot in a terminal plate slice through the insulation to engage the metallic conductor. The conductor is generally larger than the slot and the resilient force developed ,by the beams forming the opposite ends of the slot act to maintain an adequate electrical contact even though the wire may relax with time.

This resilient contact between the slot edges and the wire is one difference between an insulation displacement contact and other forms of insulation penetration or insulation piercing contact. Insulation piercing contacts can include electrical contacts in which a spike or teeth pierce the insulation and engage a round wire or other conductor at the center of the insulated cable or wire. Although the insulation need not be stripped, this type of insulation piercing contact usually does not result in elastic deformation of the more resilient terminal and there is then no storage of elastic energy to maintain a good electrical connector as the softer wire creeps or relaxes with time. For this reason, insulation displacing contacts are more common than insulation piercing contacts. An electrical connector that uses both an insulation displacement and an insulation piercing termination is shown in U.S. Patent 4,538,872.

However, one problem with insulation displacement contacts is that in some, but not necessarily all, cases stranded wire insulation displacement terminations may deteriorate over time because the stranded wires may migrate over time moving the strands out of engagement with the edges of an insulation displacement slot. Another problem is that the edges of an insulation displacement slot may cut one or more strands. One approach for using either insulation displacement or insulation penetrating connections with stranded wires is to trap the wire between terminal located on top and bottom of the wire. An example of this approach is shown in U.S. Patent 4,324,450. That patent shows the use of a threaded post and a companion nut for applying sufficient force to deform opposed stamped and formed contact sections into engagement with a stranded wire trapped between the two contact sections.

Many drop wire connectors employ a threaded post and a nut to compress nonconductive housing members so that wires positioned in the housing are forced into engagement with a terminal contact surface. For example, U.S. Patent 4,449,777 discloses a drop wire connector in which terminals having oppositely facing insulation displacement slots are positioned in a housing to splice wires positioned above and below the terminals .

In the instant invention, a spring force is generated between the terminals and the housing in which the terminals are positioned. This spring force in turn acts upon the wires or conductors that are terminated. Energy is stored in the terminals, and this energy then acts upon the electrical contact so that a reliable electrical contact can be maintained over the life of the connector in which these terminals are used.

This invention can therefore add resiliency to an insulation piercing contact. One advantage of this added resiliency is that the insulation piercing contacts provide a better electrical interface with stranded wires .

Another advantage of this invention is that resiliency is added to the electrical termination by storing energy in integral terminal springs that have a longer beam length then is possible for the insulation piercing teeth or tines that establish the electrical contact. These integral beams are formed as part of the same stamping operation in which the basic outline of the terminal is generated.

This invention also provides a configuration in which the springs formed in the terminals are backed up after they are deflected so that the spring sections of the terminals cannot be overstressed and permanently deformed.

The terminals in accordance with this invention can be used in conventional electrical connector housings of the type used in connectors that can be used to terminate wiring. These connectors can be used in an outside plant environment and the added resiliency imparted to the electrical connection can prevent deterioration to the electrical interface that can occur when contact surfaces without significant resiliency are used in these environments.

The representative embodiments of this invention therefore include one or more terminals that are positioned within a nonconductive housing. The preferred embodiments are tap connectors in which opposed terminals are mounted in opposed housings with sufficient openings between the terminals and the housings so that wires can be inserted between the opposed terminals. Preferably two wires are tapped by the insulation penetrating contact surfaces on opposite ends of each terminal . The terminals and the connector are characterized by a spring force that is developed between the terminals and the connector housing, which acts as a fixed support surface so that this spring force, or the energy stored in the terminal, can act upon the wires or conductors that are terminated or tapped by this connector. In the preferred embodiments, these spring forces are generated as the connector housings are brought together, bringing the insulation penetrating contacts sections into engagement with the wires. Spring beams integral with the terminals are flexed and engage backup surfaces on the connector housing as contact is made with the wires. In the preferred embodiment, the terminals are positioned in housing slots and the spring beam sections of the terminals are free to move within the housing slots. The bottom of the housing slots acts as a stop surface to prevent overstressing of the terminals.

The invention will now be described by way of example with reference to the accompanying drawings wherein:

Figure 1 is a three dimensional view of a distribution electrical connector using opposed terminals mounted in opposed housings to splice stranded wires of different gauges.

Figure 2 is a section view of a first version of the connector showing the opposed terminal and housing before wires are terminated. In this first version opposite ends of the terminals are spaced from the bottom of the housing slot in which the terminals are located.

Figure 3 is a section view of the first version of the connector, shown in Figure 2, with wires terminated between opposed terminals. Cantilever terminal spring arms have been deflected to store energy and the arms engage the bottom of the housing slot to prevent the terminals from being overstressed.

Figure 4 is a section view of a second version of the connector prior to wire termination. Terminal slots are stamped adjacent the inner edges of the terminals and the terminals can flex until opposite sides of the terminal slots engage.

Figure 5 is a section view of the second version of the connector, shown in Figure 4, showing the deflection of the terminals.

Figure 6 is a section view of a third version of the connector, prior to wire termination, in which terminal slots extend inwardly from opposite side edges of each terminal . Figure 7 is a section view of the third version of the connector, shown in Figure 6, with the wires terminated and tapped.

Three embodiments of an electrical connector and a terminal for use with that electrical connector are depicted in order to show representative examples of the instant invention. Each of these representative examples are specifically intended for use in a distribution connector that can be used to tap insulated cables in an outside plant environment. Figure 1 shows a distribution piercing connector 10 that is used to tap or interconnect a first wire or conductor 2 to a second wire or conductor 6. This connector is specifically intended for tapping wires of different gauges or sizes. As shown in Figure 1, wire 2 has a larger diameter than wire 6. Both wires 2 and 6 are stranded wires, with wire 2 having a plurality of round wire strands 4, and with round wire strands 8 being located in wire 6. In each case the strands 4 and 8 are surrounded by an exterior insulation sheath. Connector 10 has identical upper and lower nonconductive or insulating housings 12 that are mirror images and are positioned in opposition to each other. In this embodiment, two terminals 14 are located in each housing 12. The two connector housings 12 are joined by a threaded member or bolt 20 and a nut 22 is positioned at the top of one of the connector housings 12. When the nut 22 is rotated relative to the bolt 20, the upper connector housing is urged toward the lower connector housing, and the opposed terminals 14 located above and below wires 2 and 6 are brought into engagement with the wires positioned between the two connector housings. Each of the terminals 14 are located in a corresponding slot 24 extending into the housing 12 from an inner housing face 18. Slots 24 extend on both sides of the centrally located threaded member 20 and in the preferred embodiment the length of slots 24 are substantially the same as the length of the terminals 14. The terminals 14 can be held in the slots 24 in a number of conventional ways, such as by tabs on the terminals or housing protrusions extending into the slots. As will be subsequently discussed in greater detail, the terminals 14 must be free to deflect in the slots 24 and the retention means for holding the terminals 14 in slots 24 cannot restrict this deflection or movement .

In the preferred electrical connector embodiment shown in Figure 1, the inner housing face 14 also includes a semicircular recess 16 located on the side of the connector in which the larger wire 2 is positioned. This recess 16 provides clearance for this larger diameter conductor. The connector housings 12 are however spaced apart on both sides to provide a sufficient opening for wires 2 and 6 to be positioned in alignment with the surfaces on the terminals 14 that will engage and electrically terminate the conductive strands 4 and 8 of the respective wires. Terminals 14 are stamped and formed for a resilient conductive metal. For example brass, phosphor bronze, or beryllium copper are representative metals from which terminals 14 can be fabricated. Terminals 14 are each insulation piercing terminals and each includes insulation piercing teeth, barbs or tines located at both ends of the terminal . In each of the representative embodiments three teeth, tines or barbs are located at each end. The teeth 28 in Figure 2 are representative of the teeth in each of the three representative embodiments. Each tooth 28 has a sharp point for penetrating the outer insulation. The spacing between the two outer teeth 28 is less than the diameter of the corresponding wire, and each of the three teeth will enter the conductive core of the corresponding wire to make contact with the conductive stands. In addition to piercing the outer insulation, the teeth can also be used to initially secure the wires between the opposed terminals when the opposed housings 12 are simply pushed together until the teeth initially engage the insulation to hold the wires. In each of the preferred embodiments two parallel terminal plates are employed with side by side termination sections or teeth 28 engaging the same wire at closely spaced axial locations. Engagement by two parallel terminals can provide a redundant termination for the wires, or one terminal can act as a strain relief preventing axial forces applied to the wires from damaging the electrical and mechanical termination formed by the other terminal.

Each of the three representative terminal embodiments depicted herein is resilient, and in each case the terminal is deflected to store energy in the terminal so that the terminal can move to maintain a satisfactory electrical termination despite any tendency of the wires to move or any creep, or slight relative movement, that may occur between the terminals 14 and the wires 2 and 6, or more importantly between the teeth or tines or barbs and the wires. The three representative embodiments employ different terminal spring configurations to store the energy in the resilient terminal. The three representative embodiments differ only in the configurations of the terminal 14, 114, and 214. The same connector housings 12 are used with each terminal configuration. The first of the three representative embodiments is shown in Figures 2 and 3. Figure 2 shows the connector prior to termination of two wires and Figure 3 shows the connector after the wires have been terminated. As shown in Figure 2, the terminal 14 is positioned within slot 24. The bottom or inner edge 32 of terminals 14 is stamped so that inclined edges extend from the center of the terminal 14 towards the outer ends where the teeth 28 are located. The edges meet at the center and form an included angle of less than one hundred and eighty degrees. The center of edge 32 engages the flat bottom wall 26 of housing slot 24 with the inclined edges diverging from this central point of contact. The opposite terminal edge 34, from which teeth 28 extend, is curved. The flat terminal 14 thus has two cantilever beams 30 extending outwardly from the supported center toward the teeth 28. These cantilever beams 30 are deflectable in the plane of the contact. As shown in Figure 3, the cantilever beams 30 are deflected from the neutral state, shown in Figure 2, as nut 22 is threaded on bolt 20 causing the opposed connector housings 12 and the opposed terminals to move toward the two wires 2,6 located between the two connector housings 12. The teeth 28 engage the wires and penetrate the insulation, and then form a mechanical and electrical connection to the conductive strands 4,8. Continued tightening of nut 22 increases the force acting between wires 2,6 and the teeth 28 on the opposite ends of the terminals 14. This causes the resilient beams to flex in the plane of the terminal as constrained by housing slot 24. Ultimately the inner terminal edge 32 comes into engagement with the bottom or inner wall 26 of slot 24 along its entire length before the stress on the resilient beams 30, acting as springs, is sufficient to cause inelastic deformation. This engagement between the terminal inner edge 32 and the bottom slot wall 26 functions as an anti-overstress feature. Alternatively, deflection of the terminals 14 may take place upon engagement of the teeth with the wires 2,6. The terminals 14 may be completely deflected before any penetration of the teeth 28 occurs. The bottom slot wall 26 will function as an anti-overstress for the terminals 14.

Figures 4 and 5 show a second embodiment of the invention in which resilient terminals 114, having a different configuration, are used in the same housings 12. Figure 4 shows the connector 110 before the wires are inserted, and Figure 5 shows the configuration after the two wires are spliced. In this embodiment, each of the terminals 114 has two slots 136 stamped into the terminal 114 to form base arms 134 that extend outward from the center of the terminal along the terminal inner edge. Base arms 134 are positioned in engagement with the slot bottom wall 26 and are joined to the remainder of the terminal by a central web 140. The base arms 134 are separated from the remainder of the terminal by the slots 136. A semicircular dimple 138 is stamped near the outer end of each base arm 134, and dimples 138 extend into the slots 136 toward the terminal cantilever arms 130. As shown in Figure 5, the terminal cantilever arms 130 are again elastically deflected when the opposed terminals 114 are brought into engagement with the wires 2,6. When the inner edge of these spring beams 130 come into contact with dimples 138 on the other side of the slot 136, further deformation of the spring beams 130 is not possible. The spring beams 140 will therefore not be overstressed before they come into contact with the base arms 134 and which are in turn restrained by engagement with the bottom slot wall 26. Figures 6 and 7 show a third embodiment utilizing a different terminal 214, also positioned in the same connector housing 12. Terminals 214 also have insulation piercing teeth 228 located adjacent the opposite ends. The spring beams for this terminal configuration are formed by two slots 240 and 242 extending inwardly from opposite ends of the terminal 214. The two slots 240 and 242 are offset so that they overlap when each extends beyond the center of the terminal 214. For this terminal configuration, two spring beams are formed on opposite sides of slot 240. One set of teeth 228 are located at the free end of a first beam 244 which flexes about a root section adjacent the inner edge of the second set of teeth 228 located at the opposite end (to the left in Figure 6) of the terminal 214. The second set of teeth 228 are in turn located at the flexible end of a spring beam 246 formed between overlapping slots 240 and 242. These two spring beams 244 and 246 are deflected as the teeth 228 at their free ends engage wires 2 , 6 as shown in Figure 7. The beams 244 and 246 will engage opposite edges of the terminals 214 formed by slots 240 and 242 before the beams are overstressed. A rear or base leg 248 of the terminal is in engagement with the bottom wall of housing slot 26, and the spring beams are again backed up by the connector housing and cannot be overstressed. All three of the terminal configurations discussed herein store energy that acts to maintain a satisfactory electrical contact between the insulation piercing teeth and the terminated contact over the life of the contact. Thus the insulation piercing teeth are spring loaded and a continuous spring force acts on the terminated conductors. Furthermore this force is developed by a spring substantially longer than the length of the insulation piercing teeth. The three configurations described as representative embodiments are not the only means of providing this resilient force acting upon the electrical and mechanical contact between the terminal and the wire. Other equivalent configurations would be apparent to one of ordinary skill in the art. The use of these resilient insulation piercing contacts is also not limited to the tapping connector shown as the preferred embodiment.

Claims

WE CLAIM :

1. An electrical connector (10) for use in establishing an electrical contact with an electrical conductor (2,6), wherein the electrical connector (10) includes at least one terminal (14) mounted in a nonconductive housing (12) , the housing (12) being open to receive the electrical conductor (2,6) so that the axis of the conductor intersects the terminal (14) ; the connector (10) also including means (20,22) for imparting relative movement between the terminal (14) and the conductor (2,6) so that the terminal (14) engages the conductor (2,6) to establish electrical contact with the conductor; the electrical connector (10) being characterized in that the terminal (14) is spring biased relative to the housing (12) so that a spring force is developed as the terminal (14) and the conductor (2,6) are moved into engagement, the spring force acting to prevent relaxation of the electrical contact established between the terminal (14) and the conductor (2,6).

2. The electrical connector (10) of claim 1 characterized in that each terminal (14) engages two conductors (2,6) to splice the two conductors, each terminal (14) being spring biased so that separate spring forces act to prevent relaxation of the electrical contacts with each conductor.

3. The electrical connector of either of claims 1 or 2 characterized in that each terminal (14) is a resilient member including an integral spring (30) that engages the housing (12) .

4. The electrical connector of claim 3 characterized in that each terminal (14) is a stamped plate with the spring being adjacent one edge of the terminal and an electrical contact surface (28) adjacent an opposite edge.

5. The electrical connector of claim 4 characterized in that each terminal (14) is located in a slot (24) in the housing (12) with the spring biased against the bottom surface (28) of the slot and with the electrical contact surface (28) protruding from the top of the slot.

6. The electrical connector of claim 5 characterized in that the deflection of the spring (30) is limited to prevent overstress.

7. The electrical connector of any of claims 1 to 6 characterized in that opposed terminals (14) are located in opposed housings (12) that are joined by a threaded member (20) comprising the means for imparting relative movement between the terminal (14) and the conductor (2,6) .

8. The electrical connector of claim 7 characterized in that each terminal (14) includes conductor contact teeth (28) at two ends of each terminal with contact teeth on each end being aligned with contact teeth (28) on the corresponding end of the opposed terminal (14) so that each conductor is trapped between teeth at opposite ends of the terminal.

9. The electrical connector of any of claims 1 to 8 characterized in that each terminal (14) includes conductor contact surfaces (28) at opposite ends thereof and separate springs (30) formed in the terminal at opposite ends of each terminal.

10. The electrical connector of claim 9 characterized in that the terminal (14) comprises a stamped plate and each spring comprises a cantilever beam (30) with the deflectable end of each cantilever beam being located adjacent a corresponding end of the terminal .