Flat Cable Connectors

Abstract

A flat cable connector comprises two clamping members shaped to fit against opposite sides of a flat cable having parallel cores each embedded in its own cylindrical sheath of insulation. One of the clamping members is apertured and fixtures are provided for clamping the members together. A contact support, bearing piercing contacts, may then be drawn against the apertured clamping member so that contact tines, provided on the piercing contacts, enter respective apertures and are forced through the cable insulation to make good electrical contact with the cable section clamped between the two members.

Description

FIELD OF THE INVENTION

The present invention relates to a cable connector for electrical connection to a flat cable and having two clamping members which, in the closed position thereof, positively clamp a section of the flat cable between them, and with piercing contacts having one or more contact tines which are adapted to come into contact with respective cable cores in the zone of the clamping members and after piercing the cable insulation.

A flat cable is to be understood in the context of this specification as being a multi-core cable in which the cores -- by contrast to other multi-core cables -- extend parallel to each other without being stranded and are embedded at uniform distances from each other in a common cable insulation which takes the form of a strip having longitudinal ribs which normally correspond to the cable cores.

THE STATE OF THE ART

In some known flat cable connectors the piercing contacts are anchored on one of the clamping members and project therefrom. When such a cable connector is used, the cable insulation is usually pierced and the flat cable is consequently mechanically stressed and often deformed, before positive clamping contact between the clamping members and the external surface of the cable is established.

In other words, it is not possible with such connectors to move the clamping members into the closed position and subsequently to pierce the cable insulation when the clamping members are closed. Subsequent repositioning of the contact connector with respect to the flat cable is therefore not possible once the cable is in its clamped position, unless a defective cable insulation can be tolerated. It is this fact which is often found detrimental in practice since it is often necessary during installation to resite a cable connector by a small amount along the longitudinal extension of the cable.

The fact that penetration of the cable insulation with known connectors is obtained by means of piercing contact before positive gripping contact between the clamping members and the external surface of the cable is established, also affects the shape and dimensions of the piercing contacts. These must be constructed so that they are able not only to pierce through or displace the cable insulation in order to come into electrical contact with the targeted cable cores but they must also be able to apply the necessary contact pressure to make good electrical connection with the cores.

It has been proposed to provide the piercing contacts with bifurcated contact ends which are formed with piercing tines provided in pairs in a plane that extends transversely of the longitudinal orientation of the cable. The "pierced" cable core thus tends automatically to be centred between the piercing tines of one pair and to spread the latter slightly. The contact pressure between such piercing tines and the cable core therefore at best corresponds to the force by means of which the piercing tines themselves counteract such spreading action. This force is however often insufficient to provide contact positions for substantial currents, for example of the order of a few amperes, without the risk of oxidation occurring at the contact position after some time and thus producing an increased contact resistance.

OBJECTIVE OF THE INVENTION

It is therefore the object of the invention to provide a contact member of the kind described hereinbefore but in which the previously mentioned disadvantages are substantially eliminated.

SUMMARY OF THE INVENTION

A cable connector for a flat cable comprises, in accordance with the present invention two insulative clamping members one of which is apertured, fixtures tightenable to draw the members together to clamp positively between their opposed faces a section of the flat cable so that the cable cores extend across the apertured face, an insulative contact support on which are mounted electrical piercing contacts providing a row of space projecting contact tines on one side and respective electrical connections on the other side, and an arrangement for holding the contact support against the apertured member so that its contact tines protrude from its apertured face and embed themselves in the clamped section of the cable in physical contact with its cores.

The position of the connector according to the invention may thus be quasi "temporarily defined" by closing of the clamping members and may be altered without damage to the cable insulation before actual piercing of the cable insulation takes place. Electric connection is performed only subsequently by mounting of the contact support once the position of the contact members is defined.

PREFERRED FEATURES OF THE INVENTION

There is also a greater degree of flexibility as regards the shape of the piercing contacts because they need not be designed to apply the necessary contact pressure. This is obtained from the flat cable itself which in its clamped position is surrounded on all sides by a positive enclosure under pressure and formed by its own insulation displaced partially by the piercing contacts.

Additionally the contact tines of the piercing contacts may be serially disposed, as seen in the longitudinal orientation of the cable, and their free ends may have cutting edges which extend in the longitudinal orientation of the cable to increase the contact area.

IN THE DRAWINGS

The invention will now be described in more detail, by way of examples, with reference to the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of a cable connector for a 10 core flat cable, contacts being provided for each of the 10 cores;

FIG. 2 is a perspective view of a piercing contact of the connector of FIG. 1;

FIG. 3 is a section transverse to the longitudinal orientation of the cable and extending through part of the cable connector of FIG. 1 showing its clamping members in their closed positions and a contact support mounted thereon;

FIG. 4 shows a modified embodiment of a piercing contact; and,

FIG. 5 is a section similar to FIG. 3 through a closed cable connector which is provided with piercing contacts as shown in FIG. 4.

DETAILED DESCRIPTION OF FIRST ILLUSTRATED EMBODIMENT

The cable connector 10 of FIG. 1 basically comprises three parts: an upper clamping member 11, a lower clamping member 12 and a contact support 13 with a set of piercing contacts 27. A flat cable 14 which is to be connected contains ten cores 15 each of which is surrounded by a substantially cylindrical core insulation 16, the individual core insulations 16 being joined to each other by webs 17. The flat cable 14 therefore takes the form of a strip with longitudinal ribs on both sides, the number of ribs corresponding to the number of cores 15. The ends of the upper clamping member 11 are provided with two abutment surfaces 18 whose purpose it is to bear flat on two corresponding abutment surfaces 19 which are disposed at the ends of the lower clamping member 12. A number of grooves 20, extending parallel to the longitudinal orientation of the cable, are formed between the two abutment surfaces 18 of the upper clamping member 11, the profile section of the said grooves corresponding to the external shape of the side of the flat cable 14 which is nearest to the upper clamping member 11. A corresponding number of grooves 21 are likewise formed in the lower clamping member 12 between the abutment surfaces 19, the profile section of the last mentioned grooves corresponding to the profiled section of the side of the cable 14 which is nearest to the lower clamping member 12. Two apertures 23 of rectangular cross-section are formed in the base of each of the grooves 21 and extend rectilinearly through the member 12 to open through its undersurface 22 which faces away from the cable. The purpose of the apertures 23 is to accommodate respective piercing tines 29, 30 of piercing contacts 27 provided in the contact support 13.

The lower clamping member 12 is also provided at its ends with two threaded holes 24 for accepting internally threaded bolts 25 which extend through bores 26 provided in the ends of the upper clamping member in order to draw the two clamping members 11, 12 together around the flat cable and into the "closed" position. As may readily be seen be reference to FIG. 3 the two clamping members 11, 12 enclose the flat cable 14 positively in their closed positions so that the entire cross-section of the flat cable 14 bears on correspondingly and substantially identically shaped surface of the clamping members 11, 12.

Returning to FIG. 1 it will be seen that the contact support member 13 is provided with an upper abutment surface 33 which fits against the undersurface 22 of the lower clamping member 12. Apertures 28, one of whose contours is shown in broken outline, for respectively receiving the piercing contacts 27, open through abutment surface 33. The apertures 28 are provided to accommodate the piercing contacts 27 each of which is formed with a shank part 31 which, as shown in FIG. 2, adjoins a terminal pin 32 projecting downwardly. The upper part of each piercing contact 27 is constructed in befurcated form to provide piercing tines 29, 30 extending serially in the orientation of the longitudinal cable axis. The shank part 31 is asymmetrically disposed with respect to the piercing tines 29 and 30 so that when piercing contacts 27 are inserted into the apertures 28, the piercing tines 29 alternate with the tines 30 along one longitudinal side of the contact support member 13. In consequence the pins 30 are staggered as shown in FIG. 1, and a greater distance between adjacent pins 32 projecting from the contact support member 13 is achieved.

At each end the contact support member 13 is provided with a bolt hole through which passes a bolt 36 capable of being screwed into one of the internally threaded bolts 25.

The free ends of the piercing tines 29 and 30 taper to sharp blades at 34 so as to produce cutting edges 35 at the aforementioned free ends. These cutting edges extend parallel to the orientation of the cores 15 of the flat cable which may comprise a stranded core of fine gauge, bare wires.

METHOD OF USE

To use the cable connector 10 the cable 14 is first firmly and positively clamped between the two clamping members 11 and 12. This is achieved by screwing the bolts 25 into the threaded holes 24. When the position of the clamping members 11,12 with respect to the longitudinal orientation of the cable 14 is defined the contact support member 13 is mounted on the clamping member 12 by means of the bolts 36 which are screwed into the bolts 25. The upward drawing motion of the support member 13 is accompanied by the piercing tines 29,30 moving upwardly through the apertures 23, then through the cable insulation 16 so that the cutting edges 35 and the blades 34 penetrate into the stranded wires of the cores 15, as shown in FIG. 3. This causes the strand of wires of each core 15 to be prised apart and the surrounding insulation 16 to be correspondingly compressed and in turn apply all round pressure to the core 15. This results in a high contact pressure determined by the thickness of the piercing tines 29, 30. Since the cutting edges 35 extend substantially parallel to the individual wires of the strands of the cores 15 there is negligible risk of the cutting edges severing the bare wires of the cable when the cutting edges 35 penetrate into the core 15.

FIRST MODIFICATION

The embodiment described with reference to FIGS. 1 and 3 is unsuitable for flat cables in which the individual cores are not constructed from stranded, superfine gauge bare wire but are constructed from a single, thicker, bare wire. Piercing contacts such as those shown in FIG. 4, are provided for this purpose. The piercing contacts 27' are each constructed with a shank part 31' and a terminal pin 32' which is disposed at the free end of the shank part. In this case however the piercing contacts 27' are trifurcated to provide three end piercing tines, namely two piercing tines 29' and one intermediate piercing tine 30'. As is apparent these piercing tines are disposed longitudinally of but in an offset pattern with respect to the longitudinal axis of the cable core which is to be pierced so that the two end tines 29' lie adjacent one side of the cable while the centre tine 26' lies adjacent the other side of the cable. The free ends of the piercing tines are also provided, as may be seen by reference to FIG. 4 with chisel ends terminating in cutting edges 35' which extends parallel to the longitudinal orientation of the core that is to be connected.

The connector is assembled and used in the same manner as described with reference to FIGS. 1 to 3. However, as may be seen by reference to FIG. 5 the piercing tines 29' or 30' respectively do not penetrate the cable core 15' after piercing the cable insulation 16 but instead the cutting edges 35' shear off parts of the external surface of the bare wires 15' while the slant faces of the chisel ends ensure that the piercing tines are pressed firmly against the sheared surface of the compressed cable insulation displaced by the tine as it approaches its operating position.

OTHER MODIFICATIONS

The invention is of course not confined to cable connectors which have piercing contacts of the shape described hereinbefore. Conventional piercing contacts may also be used but the manufacture thereof usually calls for a greater technological expenditure. The piercing contacts 27 or 27' respectively may be held by frictional engagement in the contact support member 13 in which case they must be secured against axial displacement, or they may be held in position by being embedded in the contact support member 13 during its manufacture. The first embodiment, namely with piercing contacts inserted by frictional engagement, offers the advantage that only the required number of piercing contacts need be inserted with the same construction of the contact support member 13 while the remaining unused apertures are left free.

Claims

I claim:

1. A connector for a flat cable having longitudinally extending parallel conductive cores, comprising: two insulative clamping members, respective clamping faces formed on said members, a line of apertures extending through one of said members from its clamping face, fixing means tightenable to draw said members together around said cable so that said clamping faces define between them a clamping recess having a cross-section corresponding to said cable and within which said cable is tightly gripped with its cores extending across respective apertures, an insulative contact support, electrical piercing contacts fixed in said support, a row of contact tines projecting from said support at spacings corresponding to said apertures said tines being part of said piercing contacts and each having a projecting length greater than the axial lengths of said apertures in said member, means for attaching said support to said connector with said tines passing through said apertures and penetrating into said cable and in electrical contact with said cores, and electrical connection terminals on said contact support individually united with respective piercing contacts.

2. A connector as set forth in claim 1, wherein said clamping faces are formed with parallel grooves of part-cylindrical cross-section, and said apertures open into the bases of said grooves between the ends thereof.

3. A connector as set forth in claim 1, wherein each piercing contact provides two projecting tines lying in respective rows of tines and having cutting edges aligned with the longitudinal direction of the cable cores, said one clamping member having two parallel rows of apertures and said connection terminals comprising pins positioned eccentrically on said piercing contacts.

4. A connector for a flat cable having longitudinally extending parallel cores, comprising: two insulative clamping members, respective clamping faces formed on said members, two parallel lines of apertures extending through one of said members and opening into its clamping face, fixing means tightenable to clamp said members together one each side of said cable with said cable clamped in a recess formed between said faces and conforming in cross-section to the cross-section of the cable whose cores each extend across the ends of two apertures one from each line, an insulative contact support, electrical piercing contacts fixed in said support, two rows of contact tines projecting from said support at spacings corresponding to the spacing between said apertures of the two lines each piercing contact providing one contact tine in each of said rows and each of said tines having a projecting length greater than the axial length of each of said apertures, two aligned tapered ends formed on the respective tines of each piercing member, aligned linear cutting edges extending in the longitudinal direction of said cable being formed by the tips of said tapered ends, means for drawing said support against said connector with said tines passing through respective apertures and penetrating into said cable to complete electrical circuits between said piercing contacts and said cable cores, and electrical connection terminals on said support individually attached to respective piercing contacts.

5. A connector as set forth in claim 4, in which each piercing contact is provided with three tines comprising two end tines having aligned cutting edges and an intermediate tine offset laterally of a line berween said two end tines, each of said tines terminating in a chisel end having a slant face disposed on the side of the tine remote from the medial plane of the three tines, and the intermediate tine having a cutting edge which extends parallel to the cutting edges of said end-tines.

6. A connector as set forth in claim 4, in which said electrical projecting terminals comprise pins projecting from the side of the contact support remote from said projecting tines, and said pins are individually integral with respective piercing contacts and are eccentrically formed thereon and lie in two parallel rows with the pins in one pin row staggered with respect to the pins in the other pin row.

7. A connector for a flat cable having longitudinally extending parallel cores, comprising: two insulative clamping blocks, respective parallel grooved clamping faces formed on said blocks, an insulative block contact support, electrical piercing contacts fixed in said support, aligned contact tines projecting from said support and having projecting lengths greater than the thickness of one of said clamping blocks which is apertured to received said contact tines, fixing means to clamp said clamping blocks together one each side of said cable with said parallel grooved clamping faces contiguous with opposite surfaces of said cable and with said cores extending across the ends of said apertures, means tightenable to hold said support in engagement with said apertured clamping block with the projecting tines extending therethrough and in electrical contact with cores of the cable, linear cutting edges formed on the ends of said tines and aligned in the longitudinal direction of the cable, and contact pins formed on said piercing contacts and projecting from said support on the side opposite said contact tines.

8. A connector as claimed in claim 7, in which said piercing contacts each provide at least two tines having their cutting edges linearly aligned with one another and formed by the tips of wedge-shaped end portions, and each piercing contact is frictionally held in said support block.

9. A connector as claimed in claim 7, in which said piercing contacts are made from a stiff flat metal strip blank having a symmetrical arrangement of parallel sharp tines formed by one end portion and an asymmetrically arranged contact pin formed by the other end-portion.

10. A connector as claimed in claim 7, in which said fixing means comprise hollow internally threaded bolts which are tightenable in bolt holes at the ends of one of the clamping blocks, and said tightenable means for holding the support against said apertured clamping block comprises threaded bolt means which are received within said internally threaded bolts.