EP0228723A2

EP0228723A2 - Modular IDC terminal block assembly

Info

Publication number: EP0228723A2
Application number: EP86201979A
Authority: EP
Inventors: Lawrence E. Geib; Herbert C. Naylor; George G. Bauserman
Original assignee: Reed Devices Inc
Current assignee: Reed Devices Inc
Priority date: 1985-11-12
Filing date: 1986-11-11
Publication date: 1987-07-15
Also published as: EP0228723A3; JPS62117283A

Abstract

The IDC terminal block assembly according to the present invention provides an in-the-field useability with ordinary, readily available tools, and each terminal block assembly is capable of terminating any one of multiple-gauge wires. The IDC terminal block assembly is manufactured in a standard length that is selectively severable at multiple locations to provide the number of terminal positions adapted for a particular applications environment. The terminal block assembly is operable in either a pin-compatable or a printed circuit board insertable mode with only a slight modification in otherwise identical IDC terminal bodies, and is economically fabricated from three cooperative components that are readily assemblable, minimize inventory requirements, and provide positive strain relief. The three principal cooperative component sub-assemblies include plural IDC terminal bodies in one of two configurations, plural contiguous housing members, and plural cover members having yoked cam surfaces pivotally mounted individually to the several housing members. The IDC terminal bodies are slidably mounted individually to corresponding housing members and are held thereby in a stationary manner. Any of multiple gauge wires positioned in the stationary terminal bodies are urged downwardly thereinto by action of the yoked cam surface of the associated cover members in such a way that the insulation surrounding the wire is cut-through, and the material of the wire is plastically deformed in inverse proportion to the gauge thereof. The wires as terminated are recessed within the terminal block assembly in such a way that any strain along the wires is stress relieved externally of the wire-to-IDC terminal interfaces.

Description

FIELD OF THE INVENTION

This invention is directed to the field of electrical interconnection components, and more particularly, to a novel modular IDC terminal block assembly.

BACKGROUND OF THE INVENTION

Terminal blocks, commonly employed in the electronics industry for providing discrete and mass wire terminations to printed circuit (PC) or other interconnection boards, usually include several identical elements each constituted as an electrical interconnection member and a housing member. The interconnection members provide the intended wire termination function while the housings not only provide support for the terminated wires but also provide a structure for mounting the terminated wires to the PC or other interconnection board.
Multiple-part terminal and housing structures insofar as they require several separate assembly steps to bring then into their operable condition are labor, time, and materials intensive. The multiplicity of assemblable parts are subject to loss and/or damage, making for considerable work and use difficulties. The several parts are expensive to severally fabricate, and inventory requirements of different dedicated storage locations therefor grow with the number of the parts.
The terminal bodies are typically configured either as pin-mateable or as PCB-insertable configurations, and are available in different lengths to meet the requirements of the particular application. Terminal bodies having the different mounting configurations in multiple lengths must then be severally stockpiled at a considerable inventory space requirement. Different, and costly, molds or other forming devices, moreover, must be dedicated for each of the several different-length terminal block assemblies, which then entails considerable preproduction costs.
The interconnection members of the terminal blocks are typically of two types, the insulation displacing (IDC) type and the non-IDC type, the latter being generally disadvantageous insofar as the individual wires to be terminated must be prepped beforehand in a separate step in order to insure the requisite interconnection. The insulation displacing type interconnection members have resilient cutting blades that flex apart as they cut through the insulation surrounding the electrical wires to be terminated. But with multiple insertions and removals, a mechanical strain builds-up in the material of the fingers in such a way as to reduce their operative lifetime. The material of the confronting walls of the housing member against which the blades are restrained in their flexing motion, typically a plastic material, tends to deform, due to the phenomenon of cold-flow/creep, which therewith gives rise to the possibility of less than desirable wire termination. Elaborate and costly designs have thus been necessary heretofore to accomplish a measure of strain relief so as to insure the possibility of a reliable, repeatable termination.
Differently sized IDC terminals are commonly provided in separate housings each dedicated to accepting a different gauge wire to be terminated. The corresponding gauge terminal block if it is unavailable, requires it to be specially ordered with a consequent undesirable delay. Separate stockpiles of the differently dimensioned terminals may be severally provided for the corresponding gauge sizes, and separate stockpiles of different terminal blocks for the correspondingly different gauges, may be severally provided to insure ready availability, but only at considerable storage space and inventory requirements.
A fixturing assembly is usually used during the termination process such as specialized pliers for terminating wires into their associated insulation displacing terminals. If this tool is lost or otherwise unavailable, it would not be practicably possible to terminate the wires, since only the tool imparts the requisite mechanical advantage that overcomes the resistance of the wires being terminated. The tool, to the extent that it must be specially provided, itself is costly to procure and manufacture and often is clumsy to handle and in use may result in damage to the terminal block.

SUMMARY OF THE INVENTION

The novel terminal block assembly of the present invention overcomes these and other disadvantages and includes a longitudinal array of individual modules joined by severable webs to accomodate the termination needs of any one of a number of particular applications. Each module of the terminal block assembly is operable to terminate any one of several different gauge wires so that point of use termination flexibility is achieved and stockpile requirements are materially relaxed. A screwdriver, or pliers are useable to provide individual wire termination which eliminates any need for specially provided fixturing assemblies. The terminal block assembly of the present invention moreover has a simple design that is inexpensive to manufacture, is easy to assemble, use, and to handle, and that is operable in either a pin-mateable or a PCB-insertable configuration.
The novel modules of the IDC terminal block assembly of the present invention include an insulation displacing terminal body that is slidably received in a housing member in such a way that the terminal body is recessed within the housing and is spaced along an elongated stress relieving slot defined by the housing member. The insulation displacing terminal body has solid spaced fingers, that are stationary, unflexing members, operative to slice through the insulation surrounding a wire to be terminated while deforming the material of the wire without any damage thereto, such as cutting or breakage. The stationary fingers of the insulation displacing terminal bodies prevent a cold-flow/creep condition, so that different gauge wires received therein are themselves deformed to a degree that depends on their relative thickness. The recessed position of the terminal body and the elongated stress relieving slot cooperate such that the wire terminations of the different gauge wires are each strain-relieved externally of the housing so that the mechanical and electrical interconnection is positive and secure notwithstanding the degree to which the wire is deformed.
A cover member is releasably snapped into the top of the housing for pivoting motion between an open position, that allows access to the recessed insulation displacing terminal, and a closed position, which positively retains a terminated wire securely within the elongated stress receiving slot. A yoked cam is integrally formed with the cover in position to straddle either side of the insulation displacing terminal such that during pivoting motion between the open and closed positions the yoked cam bears down on both sides of the terminal and uniformly presses the wire to be terminated into the insulation displacing terminal body. The cammed cover is cooperative with the elongated slot and terminal body to both terminate the wires individually and to provide an additional measure of strain relief.
The housing member of each of the modules of the terminal block assembly has surfaces defining an internal terminal guideway. First and second walls defining first and second apertures are provided in the housing for communicating the internal terminal guideway with different portions of the bottom surface of the housing. The guideway, and the first and second apertures, make possible the use of the same, but differently configured insulation displacing terminal bodies to respectively provide PCB-insertability and plug-mateability.

DETAILED DESCRIPTION OF THE DRAWINGS

These, and other, features and advantages of the present invention will become apparent to one skilled in the art as the invention becomes better understood by referring to the following solely exemplary and non-limiting detailed description of a preferred embodiment thereof, and to the drawings, wherein:

Figure 1 is schematic plan diagram of an IDC terminal block assembly constructed in accordance with the present invention;
Figure 2 is an exploded perspective view of a constituent module of the IDC terminal block assembly according to the present invention;
Figure 3 is a sectional view along the lines 3-3 of Figure 2 illustrating the internal terminal guideway, the two openings through the bottom surface of the housing member, and the same but differently configured insulation displacing terminal bodies receivable therein to provide either PC-insertability or plug-mateability of the IDC terminal block assembly of the present invention;
Figure 4 illustrates in Figures 4A and 4B sectional views showing the way the stress relieving elongated slot, recessed insulation displacing connector body, and stress relieving cam act to terminate strain externally of the housing member of the IDC terminal block assembly according to the present invention; and
Figure 5 illustrates in Figures 5A, 5B and 5C different gauge wires in the state of termination in the same insulation displacing terminal body of the IDC terminal block assembly of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to Figure 1, generally designated 10 is a schematic plan view illustrating a presently preferred embodiment of the IDC terminal block assembly according to the present invention. The terminal block assembly 10 includes a linear array of constitutive identical modules 12, preferably sixteen (16) in number, interconnected by corresponding ones of severable webs 14 integrally formed between adjacent modules 12 along the longitudinal axis of the terminal block assembly 10. As will be appreciated, any of the severable webs 14 are readily trimmable, by the manufacturer, or at the product distribution location, to provide that number of modules adapted for the termination requirements of a particular applications environment. The terminal block assembly 10 is preferably fabricated by well-known plastics molding techniques.
Referring now to Figure 2, generally designated at 16 is an exploded perspective view of a module of the IDC terminal block assembly according to the present invention. Each of the modules 16 include a housing member generally designated 18, a stress relieving cover member generally designated 20 pivotally mounted releasably to an edge of the housing member 18, and an insulation displacing terminal body generally designated 22 removably slidably received in opposing slots generally designated 25 centrally provided therefor in opposing reinforced sidewalls 26 of the housing member 18. The terminal body 22 has spaced fingers 27 defining an outside dimension therebetween, and the opposing walls 26 defined a maximum inside dimension between the slots 25. The maximum outside dimension and the maximum inside dimension are selected such that the opposing surfaces of the walls 26 always abut the fingers 27 for providing a guide during assembly of the terminal bodies 22, into the housing 18. The slots 25 are formed generally centrally along the length of the reinforced walls 26 such that the wire-to-IDC terminal interface is recessed within the body 18, which provides strain relief in a manner to be described. The spaced walls 26 defined therebetween an elongated stress receiving slot generally designated 28, and the IDC terminal body receiving slot 25 is in communication with the slot 28 at an interior position of the member 18. Opposing spaced-apart posts 30 are integrally provided with the housing member 18 to either side of the sidewalls of the member 18.
The cover 20 is an elongated beam 32 having an integral end portion 34 on opposing sides of which bearing races 36 are provided. These races 36 have partial annular walls 38 defining a slot generally designated 40 therethrough located on that radius of the annular races 38 that is generally parallel with the direction of elongation of the beam 32. The cover 20 is slidably inserted into the housing 18 such that as the slots 40 pass through the posts 30 the cover 20 is releasably snapped thereonto and mounted thereon for pivoting motion relative to the housing member 18 between an open and a closed position.
A yoked cam generally designated 42 is integrally formed with the beam 32 of the cover 20. The cam 42 includes first and second spaced lobes 44, 46 repectively positioned to straddle either side of the insulation displacing terminal 22 so as to bear against and urge both sides of a wire received in the contact body 22 to force it therethrough as the cover 20 pivots into its closed position. The motion of the wire through the stationary fingers 27 of the insulation displacing terminal body 20 acts to cut through the insulation surrounding the wire and to plastically deform the material of the wire itself to an extent that depends on the particular gauge of the wire being terminated.
A resilient flange 47 is integrally formed with the cover 20 on the edge thereof remote from the edge at which the cover is pivotally mounted to the housing 18. The flange 47 cooperates with spaced confronting resilient abutments 48 integrally formed on the edge of the housing 18 remote from the edge thereof having the posts 30 to provide a latching action that releasably retains the cover 20 in its closed position. The dimensions of the flange 47 and flexible abutments 48 are selected to provide a frictional retaining force that is greater than the nominal upward force that is exerted thereagainst by compressed insulation of the terminated wire. As will be appreciated, any other suitable releasable latch can be employed without departing from the inventive concept.
A push down tool receiving slot generally designated 50 is provided in the beam portion 32 of the cover 20. The push down tool receiving slot is cooperative with any suitable commonly available instrument, such as a screwdriver, to retain the tool against sliding motion so as to allow the downward mechanical force imparted thereby to pivot the cover into its closed position.
Bevelled edges 52 are provided at the free ends of the fingers 27 of the terminal body 22 for guiding a wire to be terminated into a slot generally designated 54 formed thereinbetween. Bevelled blade portions 56, likewise having bevelled guide surfaces 58, are integrally formed within the slot 54. These blades preferably are fabricated of a plated copper alloy, and have sufficient strength imparting characteristics such as material thickness, the use of work-hardened materials, and the like, to provide such rigidity to the fingers as to prevent their flexing motion during termination. The fingers are operative to slice through insulation and plastically deform the conductor(s) of a wore moved downwardly therethrough by a well-known terminating action.
Referring now to Figure 3, generally designated at 60 is a sectional view of a module of the terminal block assembly of the present invention as taken along the lines 3-3 of Figure 2. The housing 18 is formed with an integral generally V-shaped wall 62 (also viewable in Figure 2) that defines a terminal receiving guideway therein. Walls 64, 66 defining apertures generally designated 68, 70 are provided at spaced points in the bottom of the housing 18 that intercommunicate the internal terminal guideway defined by the generally V-shaped walls 62 with the external bottom surface of the housing 18. The guideway defined by the wall 62, and the apertures 68, 70, cooperate to provide either a plug-mateable or a printed circuit board insertable module configuration.
Referring now briefly to Figure 2, the terminal body 22 is provided with an integral electrode tail 72. In the case of the PC board-insertable embodiment, the tail 72 and the fingers 27 share a common axis of elongation such that the electrode tails 72 extend through the apertures 68 and beyond the lower surface of the housing as shown in Figure 2 and as shown dashed in Figure 3. The axially extending electrode tail 72 defines a pin that is readily mounted into a hole provided therefor in a printed circuit board 74 and retained therein as by solder 75 for establishing a good electrical connection.
In the plug-mateable configuration, the electrode tails 72 of the terminal bodies 22 are pre-bent into a generally V-shaped configuration that matches the shape of the walls 62 as shown generally at 76. In this embodiment, a pin 77 extending off a pin body header 78 that is mounted to the printed circuit board 74 is received through the aperture 70 and mechanically and electrically contacts the bent end 76 of the tail of the terminal body. It should be pointed out that the guideway and cooperative apertures thus make possible the use of the same but only differently configured insulation displacing terminal body in either a plug-mateable or PCB-insertable block configuration. The terminals for each configuration are, for example, stamped by well-known metal working techniques on a leadframe in unison, and can then be bent in a suitable press for the plug-mateable configuration or left in the un-formed condition for the PCB-insertable configuration.
Referring now to Figures 4A and 4B, generally designated respectively at 80 and 82 are top and side views illustrating both the point of wire-to-IDC terminal termination and the manner by which strain relief is accomplished. A wire 82 is shown terminated between the fingers 27 of the terminal body 22 received in the slot 28 provided therefor in the housing 18. The wire 82 longitudinally extends through the elongated slot 28, and the terminal body 22 is recessed within the housing 18 by a distance "D" from the insertion face of the member 18. If the wire 82 is flexed to the side as illustrated by dashed outline 84, and if it is flexed vertically as illustrated by dashed outline 85, flexing stresses produced thereby and as schematically illustrated by force arrows 86, 87 are terminated in the outer face of the housing member 18, and in such a way that the resulting strains are externally relieved remote from the recessed terminal body 22 leaving the termination substantially uneffected by the flexing stresses.
The walls defining the recessed elongated slot 28, the stress-relieving cover 20 in its latched-down condition, and a shoulder 88 cooperate to effectively hold the wire 82 in a precise, movement-free spacial orientation. Any stressing forces acting through the wire, therefore, are terminated in the housing well-short of the wire-to-terminal interface and outside the housing, which makes possible the secure retention of the wire in the terminal even where the wire is deformed a considerable portion of its diameter. Multiple-gauge wires therewith are capable of being accepted in the same insulation displacing terminal body.
Referring now to Figure 5, generally designated at 90 in Figure 5A, at 92 in Figure 5B, and at 94 in Figure 5C are schematic views illustrating the state of termination of different gauge wires respectively. In Figure 5A, an exemplary 18 gauge insulated wire 96 is shown terminated in the fingers 27 of the terminal body 22 where the diameter of the 18 gauge wire is deformed approximately 46 percent. In Figure 5B, an exemplary 20 gauge insulated wire 98 is shown terminated therein in such a way that its diameter is deformed approximately 20 to 25 percent. In Figure 5C, an exemplary 22 gauge wire 100 is shown terminated with approximately 15-19 percent of its diameter deformed. The dimensions of the terminal body slots are preferably selected to be the median of the multiple gauge wires to be terminated therein. In each of the different gauge terminated wires illustrated in Figures 5A-5C, the yoked cams of the associated cover members urge the wires 96, 98, 100 into fingers 27 having the same physical dimensions, which because of their being stationary in nature, effect the plastic deformation of the material of the wires to the correspondingly different degrees respectively illustrated in the Figures. Since strain is effectively relieved externally by the housing, the different gauge wires are securely terminated therein notwithstanding the degree to which the wires are deformed.
In brief summary, the present invention thus makes possible the provision of a terminal block assembly having any selected number of modules, each independently capable of accepting multiple gauge solid or stranded wires, where termination is accomplished readily in-the-field with commonly-available tools. The modules of the terminal block assembly have pivoting cover members having integral bearing surfaces that are cooperative with the insertion tool to retain unprepared wires in insulation displacing terminal bodies. The housing member of the modules includes a terminal guideway in communication with the bottom thereof through first and second apertures and the same but differently configured terminal bodies can be received in the guideways in such a way that the resulting terminal body configuration is either plug-mateable or PCB-insertable. The whole assembly minimizes inventory requirements, materially simplifies the assembly process, and is capable of low-cost fabrication while still providing highly-reliable and repeatable termination.
Many modifications of the presently disclosed invention will become apparent to those skilled in the art without departing from the scope of the appended claims.

Claims

1. A multiple gauge wire accepting insulation displacing terminal block assembly, comprising:
plural modules;
means for severably interconnecting said plural modules in a linear array;
each of said modules including:
a housing member having spaced upstanding solid reinforced sidewalls and an integral bottom wall therebetween defining an open wire receiving top face and a strain relief wire receiving elongated slot intermediate the upstanding solid sidewalls;
said spaced upstanding solid reinforced sidewalls having first and second confronting terminal body receiving slots integrally formed generally centrally therealong and defining a preselected maximum inside dimension therebetween;
an insulation displacing terminal body having a head portion and an integral tail portion, said head portion having confronting spaced cutting fingers defining a preselected maximum outside dimension therebetween; and
said preselected maximum outside dimension of said fingers and said preselected maximum inside dimension defined between said confronting slots being selected such that said insulation displacing terminal body is slidably receivable in said confronting slots in such a way that the confronting surfaces of the fingers and of the slots are everywhere in physically abutting relation for providing sufficient means of securing the terminal within the housing.

2. The invention of claim 1, wherein said bottom wall of said housing has an internal surface having a preselected shape and confronting said wire receiving slot defining a terminal body tail portion guideway; said bottom wall of said housing having first and second spaced apertures therethrough each in communication with said internal terminal body tail portion guideway and externally extending through said bottom wall.

3. The invention of claim 2, wherein said head portion and said tail portion of said terminal are aligned along a linear axis; and wherein said terminal body is slidably received in said slots provided therefor in said housing member such that said tail portion of said terminal body extends through one of said apertures and outwardly beyond said housing for PCB-insertion.

4. The invention of claim 2, wherein said tail portion of said terminal body is predistorted about a preselected non-linear axis selected to match the preselected shape of the internal guideway such that when the terminal is slidably mounted in the housing member the end of the electrode tail is in physical proximity to one of said apertures in said bottom wall of said housing to provide plug compatability.

5. The invention of claim 1, further including a strain relieving cover member; means coupled between said cover and said housing member for mounting said cover to said housing member for pivoting motion between an open condition that allows access to the strain relief wire receiving elongated slot of the housing and a closed condition that retains an inserted wire in the strain relief wire receiving elongated slot; said cover member having an integral cam member formed thereon for urging a wire to be terminated into the insulation displacing terminal body as it is moved between its open and closed conditions.

6. The invention of claim 5, wherein said pivoting means includes integral posts formed on said housing member defining a pivot axis and integral bearing surfaces integrally formed with said cover member that are cooperative to releasably snap together.

7. The invention of claim 5, wherein said cam includes a yoked bearing surface.

8. The invention of claim 7, wherein said yoked bearing surface includes first and second selectively spaced integral projections so selected as to straddle both sides of said terminal body in the closed condition of the cover.

9. The invention of claim 5, further including means for releasably latching said cover member in said closed condition.

10. The invention of claim 9, wherein said latching means includes a resilient flange integrally formed on the end of the cover member remote from its pivoting end and resilient abutments integrally formed on the housing that are cooperative to releasably-snap the cover in said closed condition.

11. The invention of claim 1, wherein said severable interconnecting means includes an integral web formed between adjacent ones of said modules.

12. The invention of claim 1, wherein said housing is fabricated of a plastics material.

13. The invention of claim 1, wherein said fingers of said terminal body are so constructed that they are inflexible and stationary with respect to any of multiple gauge wires being terminated therein.