Connector Termination to Flat Cable

Automobile air bags are inflated when an initiator circuit passes current to a squib. The initiator circuit is connected through a cable whose front end is terminated to contacts of a connector that are connected to the squib. My earlier U.S. Pat. No. 5,288,242 describes such a cable and connector assembly. Although the circuit may lay unused for years, it is critical that the electrical connections be intact during a possible crash, when the airbag must be deployed. As a result, the cable conductors must be very reliably terminated to the connector contacts. Since cost is of great importance in consumer products such as automobiles, the cable, connector, and termination method must be of low cost design.

In accordance with one embodiment of the present invention, an assembly of a connector and cable is provided which assures a highly reliable connection between the cable conductors and connector contacts while the contacts lie within the connector housing. The connector housing has a rear portion with upper and lower walls, with the walls having aligned through holes. The cable conductors have exposed front portions that lie facewise against rear portions of sheet metal contacts of the connector. The conductors and contacts are joined in a weld joint by the use of resistance welding electrodes that pass through the openings to sandwich the conductors and contacts between them and then pass current through them, the electrodes then being withdrawn.

The connector housing can have bumps received in cutouts at the edges of the cable for cable locating and for strain relief. Strain relief is further provided by a projection with a front end held up by a web that is broken to push down the projection and allow its front end to snap forward and resist upward movement.

The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.

FIG. 1 is a front and top isometric view of an assembly of a connector and cable constructed in accordance with one embodiment of the present invention.

FIG. 2 is a partial exploded isometric view of the assembly of FIG. 1, showing only the rear portion of the connector.

FIG. 3 is a plan view of the upper housing part of the connector of FIG. 3.

FIG. 4 is a plan view of the lower housing part of the connector of FIG. 3.

FIG. 5 is an exploded sectional view of the assembly as taken on lines 5--5 of FIGS. 3 and 4, and also showing, in phantom lines, a second embodiment of the invention.

FIG. 6 is a rear view of the connector of FIG. 2.

FIG. 7 is a view taken on the line 7--7 of FIG. 6.

FIG. 8 is a view similar to that of FIG. 7, but prior to full assembly.

FIG. 9 is a partial sectional view of a connector of another embodiment of the invention, shown prior to full assembly to the cable.

FIG. 1 illustrates an airbag cable and connector assembly 10 which includes a cable 12 with a rear end that is connected to an initiator circuit (not shown). The initiator circuit senses a crash and delivers a current through conductors 14, 16 of the cable and through contacts 20, 22 of the connector 24 to a squib that initiates burning of a propellant to inflate an airbag. The assembly is somewhat similar to that described in my earlier U.S. Pat. No. 5,288,242, wherein the cable includes round insulated wires, with the connector contacts being formed of sheet metal and crimped to the wires. With increased availability of high quality flat ribbon cables, applicant prefers to use such a cable 12 and terminate its conductors to the sheet metal contacts 20, 22 in a manner that provides even higher reliability of electrical connection of cable conductors to contacts.

The connector 24 includes a dielectric housing 26 with upper and lower housing parts 30, 32 that hold the contacts in place. As shown in FIG. 2, the cable includes insulation 34 that surrounds the cable conductors. Applicant prefers to employ a protective sheet 36 against the insulation, with the protective sheet having the same width and outline as the insulation. The insulation has a width W which is a plurality of times greater than its thickness T, and each of the conductors such as 14 has a width A which is a plurality of times greater than its thickness B. The housing has a rear portion 40 with upper and lower walls 42, 44, with a front portion of the cable being sandwiched between the walls and contacts in the final installation. The upper wall has a pair of through holes 44, 46, and the lower wall has a pair of corresponding through holes 50, 52. The holes in the upper and lower walls are aligned, in that at least a portion of each upper hole 44, 46 is in line with at least a portion of a corresponding lower hole 50, 52.

The sheet metal contacts (which are similar to those in my earlier patent) have rear portions 53, 54 which are flat and which lie over the holes 50, 52 in the lower wall 44. The cable is terminated by first laying it in place so exposed front portions or ends 14E, 16E lie on top of the contact rear portions 53, 54, which lie in alignment with the holes in the upper and lower walls. The insulation 34 of the cable, as well as the protective sheet 36 are formed with cutouts 60 that receive part-cylindrical bumps 62 formed in upstanding sides 64, 66 of the largely trough-shaped lower housing part. The cutouts 60 that receive bumps 62, maintain the position of the cable while also providing strain relief. Then, the upper housing part 30 is snapped in place over the lower housing part. The upper housing part is largely trough-shaped, with opposite sides 70, 72 depending from laterally (in directions L) opposite sides of the upper wall, and which move next to the sides 64, 66 of the lower housing part. The upper sides 70, 72 have apertures 76 which receive projections 78 on the; lower sides to keep the housing parts snapped together. After the cable has been trapped in place between the upper and lower housing parts, lower electrodes 80, 82 are projected upwardly through the holes 50, 52 in the lower wall while upper electrodes 84, 86 are projected down through the holes 44, 46 in the upper wall, until the contacts and conductors are sandwiched between the electrodes. Current is then passed between the electrodes to resistance weld each contact to a corresponding conductor.

FIG. 7 illustrates the final assembly 10, showing a resistance weld joint 90 between a contact rear end 53 and a conductor front portion 16E. The upper wall carries a downward projection 92 that presses the cable 12 into a recess 130 in the lower wall 44, to provide enhanced strain relief. The protective sheet 36 helps to protect the cable at this deformed location, as well as rearwardly of the connector, with the cable passing through an open rear end of the housing. It is often desirable to provide a plurality of weld joints, such as at 90A and 90B in addition to the joint 90. The elongated slots, whose lengths in the, forward-rearward directions F, R are preferably at least twice their widths in the lateral direction, facilitate such multiple welds.

The projection 92 is initially in the position shown in FIG. 8, with a front end 120 of the; projection connected through a thin web 122 to a main portion 123 of the upper wall at a retain location 42A. The projection 92 and upper wall main portion are integrally molded, with rear end 125 of the projection being bendable. A worker forces down the projection by pressing down a tool 124 to break the web 122. Once the projection 92 moves down to the position of FIG. 7, its front end 120 moves forward and snaps under the upper wall retain location 42A, which keeps the projection down.

FIG. 7 shows the front end 120 trapped under the upper wall location 42A, and with the middle or bottom 126 of the projection holding the cable depressed into the recess 130 in the lower housing part 32. The walls of the recess 130 and the projection 92, resist pullout of the cable. The bendable rear end 125 confines the projection to pivoting, while the projection front end 120 limits the pivot position in conjunction with location 42A.

FIG. 8 illustrates, in phantom lines at 100, an alternative upper housing part rear portion which is pivotally connected at a living hinge 102 to the rest of the upper housing portion. First, the cable is laid in the lower housing part 32. Then the pivotally connected part 100 is pivoted into place, and snapped in position by apertures (e.g. 76 in FIG. 2) in the portion 100 that receive projections on the lower housing part 32. Then, as shown in FIG. 7, the part 92 is pushed down. Then, the cable conductors and contacts are welded together. The embodiment shown in phantom lines in FIG. 8, allows the upper and lower housing parts and the contacts to be fully assembled by the connector manufacturer, with the customer having only to install the cable, pivot the hinged part, and make the welds.

For the upper housing part shown in solid lines at 30 in FIG. 5, the upper housing part has a forward lip 110 that is received within and hooked under a hook 112 at the front of the lower housing part. The upper housing part is then being pivoted about its lip so its rear end moves down until the apertures 78 receive corresponding projections.

FIG. 9 illustrates a modified connector with a bendable projection 140 that has teeth 142 that bite into the protective sheet 36. The lower housing part 144 forms a recess 146 that has a rounded concave shape, with a radius of curvature at least one-half of the projection length (between ends 150, 152). The concave recess 146 and convex projection 140 provide a large area where the recess walls engage the cable to provide high friction thereat.

While terms such as "upper" and "lower" have been used to aid in the description of the invention as illustrated, it should be realized that the assembly and its parts can be used in any orientation with respect to Earth's gravity.

Thus, the invention provides a connector with sheet metal contacts which are terminated in a highly reliable manner to conductors of a flat ribbon cable. Such termination is by weld joints between the cable conductors and connector contacts, with the weld joints made through openings in upper and lower walls at the rear of the connector through which welding electrodes can pass. The cable can have cutouts that receive bumps in connector sidewalls, and the cable and a protective sheet thereon can be locked in position by a projection depending from the upper wall which presses against the cable to press it into a recess in the lower wall. The projection can be flexible and have an end that snaps under an upper wall location to lock the latch down when it is forced down.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.