Electrical Plug Connector and Method of Terminating a Cable Therewith

This invention relates to electrical connectors and more particularly to electrical plug connectors of the DIN type.

Electrical connectors of the DIN type are known and they include a dielectric housing in which three to eight electrical terminals are molded. The terminals are soldered to electrical conductors of a shielded cable. Metal clamshell members are mounted onto the housing with one of the clamshell members having a U-shaped ferrule that is crimped onto the metal shield of the cable to terminate the shield and provide strain relief. An insulating strain relief member is disposed or molded onto the clamshell members and engages the cable adjacent the U-shaped ferrule thereby holding the clamshell members in position on the housing and providing a strain relief.

Soldering of conductors to terminals is time-consuming and cold solder connections can take place. The crimping of the U-shaped ferrule onto the metal shield does not result in a good termination or an effective strain relief. If the insulating strain relief member is pushed onto the clamshell members, there is not a desirable approach to holding the clamshell members in position. If the insulating strain relief member is molded onto the clamshell members, the open area of the back end of the clamshell members must be covered or have viscous dielectric material positioned therein prior to molding to prevent material of the strain relief member from entering the soldered terminations which may break the terminations.

U.S. Pat. No. 4,493,525 teaches an improved DIN-type connector wherein a pair of metal clamshell members are mounted onto a housing member into which terminals terminated to conductors have already been inserted and secured. One of the clamshells have an inwardly-directed arcuate projection disposed in a U-shaped recess along the housing member; the clamshell members have mating lugs and flange recesses, and together form a forward annular hood shielding and protecting the forward contact sections of the terminals in front of the housing member. The clamshell members are necked down at their rearward ends to smaller U-shaped sections forming an annular member surrounding the wire conductors, and onto the U-shaped sections is positioned the braided metallic shield of the shielded cable. A ferrule member placed loosely on the cable is then brought forward over the braid and the clamshell U-shaped sections and crimped thereto forming an excellent mechanical and electrical connection as well as a cable strain relief, and simultaneously securing the clamshell members onto the housing member.

When used in certain specialized applications, such as for high frequency signals, the plug connector of the prior art having a two-part shell and a small seam or gap between the shell members has a disadvantage in that such a gap causes circumferential discontinuity in the shielding and nonuniform ground current distribution. And especially where the ground terminal of the receptacle engages the metal shell of the plug connector at only one location and therefore to only one of the shell members, the shielding effectiveness of the other shell member is reduced. A further disadvantage of the two-part metal shell is that oxides may form in the small gap which eventually cause a deterioration in shielding effectiveness.

It is desirable to provide an improved DIN-type connector having fewer parts. It is also desirable to provide metal shielding means for such a connector which provides improved, circumferentially continuous, 360-degree shielding capability and also better "hoop" strength. It is further desirable to provide a more simplified method of assembly thereof and of application of such a connector to a shielded cable.

According to the present invention, an electrical connector of the plug type comprises a dielectric housing member in which electrical terminals are to be secured, contact sections of the electrical terminals are to extend outwardly from a front surface of the dielectric housing member, and conductor-securing sections of the electrical terminals are previously connected to electrical conductors of a shielded cable. A one-piece metal shell member having a continuous circumference is mounted onto the housing member prior to insertion of the terminals into passageways of the housing member and being secured therein, forming an outer contact for the connector. The one-piece shell member is drawn having a cylindrical front section and a necked-down rear section of smaller diameter. The cylindrical housing member has an axially extending recess partly along a preselected side from the front surface thereof and is inserted into the shell member prior to the terminals being placed in the housing member. An inwardly-directed dimple-like depression is now formed in the metal shell by an indenter die to extend into the axially extending recess in the housing member at the rearward end of the recess to secure the housing member in the shell member. Forwardly of the front surface of the housing member and the depression thus formed there is also formed in the metal shell a U-shaped channel aligned with the recess which serves as a polarizing means when the connector mates with a receptacle. The housing's recess thus is utilized as a polarizing indicator.

With the ferrule member loosely positioned on the shielded cable and the terminals terminated to individual conductors of the cable, the terminals are now insertable through the rear section of the metal shell into respective terminal-receiving passageways of the housing member and latchably secured therein with contact sections of the terminals extending forwardly of the housing member and being surrounded by a front portion of the metal shell extending forwardly of the housing member. The braided metallic shield of the shielded cable is positioned over the rear section of the metal shell, and the ferrule member is brought forward along the cable to surround the metallic shield on the rear section so that the ferrule member can be crimped onto the rear section with the metallic shield crimped therebetween. The ferrule member is then crimped onto the insulating jacket of the cable. An insulating sleeve is then disposed over the metal shell, the ferrule member and a portion of the cable to insulate the connector and also provide cable strain relief. The metal shell is an outer contact for the connector and when mated to a receptacle is engaged by a ground contact member of the receptacle thus grounding the metal shell and the shield of the cable.

FIG. 1 is an exploded perspective view of the parts of the electrical plug connector.

FIG. 2 is similar to FIG. 1 showing the housing member secured in the metal shell.

FIG. 3 is a perspective view of the assembled plug connector and a mating receptacle therefor.

FIG. 4 is a longitudinal sectional view of FIG. 3.

A plug connector 10 is illustrated in FIG. 1, having a housing member 20 and a metal shell member 40 and further comprising a crimping ferrule member 60 and a cable guard member 70. Plug connector 10 is to be terminated onto a shielded cable 100 which has insulated electrical conductors 102 positioned within an inner dielectric sheath 104 around which is disposed a braided metallic shield 106 that is covered by an outer insulating jacket 108. Electrical terminals 90 are stamped and formed from a suitable metal in accordance with conventional stamping and forming operations and they include pin contact sections 92 and conductor-securing sections 94. After cable 100 has been stripped to expose the conductive cores of electrical conductors 102 and a suitable amount of shield 106, conductor-securing sections 94 of electrical terminals 90 are crimped onto the conductive cores of electrical conductors 102 in accordance with conventional crimping practices. Alternatively, shielded electrical cable 100 can be formed with electrical conductors twisted together and wrapped with a thin plastic film and the shield can be in the form of a thin metal foil wrapped around the plastic film-encased electrical conductors with a stranded electrical wire extending along the cable within the wrapped metal foil. The cable can, of course, take other forms as desired.

Dielectric housing 20 is molded from a suitable plastic material and has terminal-receiving passageways 22 extending therethrough which preferably vary in number from three to eight. Housing 20 preferably has a simple cylindrical shape, with a forward face 24, a rear face 26, and a U-shaped recess 30 extending axially rearwardly from forward face 24 at least partially along side 28. Metal shell 40 is preferably deep drawn from a suitable metal or is otherwise of a single seamless piece, and preferably has a simple cylindrical sleeve-like body section 42 and is necked down at its rear end to a smaller annular rear section 44. Crimping ferrule member 60 is preferably a circumferentially continuous metal member.

As illustrated in FIG. 2, housing 20 is inserted into body section 42 of shell 40 with forward face 24 facing forwardly and positioned at the resultant annular stop shoulder 46 at the rearward end of body section 42. Housing 20 is then secured in shell 40 by means of an inwardly-directed dimple-like depression 48 being formed in shell 40 by an indenter die (not shown) extending into a portion of U-shaped recess 30 of housing 20. Forwardly of housing 20, in front portion 52 of shell 40 and preferably axially aligned with recess 30 (and depression 48), is formed an inwardly-directed generally U-shaped channel 50 which may be formed simultaneously with depression 48 by the same indenter die. It can be seen that U-shaped recess 30 may be placed at a preselected angular orientation on housing 20 with respect to passageways 22 to serve as an indicator for a polarizing means, so that a channel 50 formed in shell 40 aligned therewith can serve as a polarizing means when the fully assembled and cable-applied plug connector is electrically mated with a receptacle 200, such as is shown in FIGS. 3 and 4, having a corresponding polarizing means (U-shaped recess 208) which assures that contacts 90 of the assembled connector mate with appropriate receptacle contacts.

With reference to FIG. 4, terminals 90 terminated onto conductors 102 are now inserted through rear section 44 of shell 40 which it can be seen should be of a large enough diameter to facilitate insertion of the plurality of terminals therethrough. The terminals 90 terminated onto conductors are urged forwardly into passageways 22 of housing 20 and are latchably secured therein via spring lances 96 engaging forward retention surfaces 32 and stop sections 98 of conductor-securing sections 94 engaging rear stop surfaces 34 so that pin contact sections 92 extend outwardly from the forward face 24 of housing 20 as shown in FIGS. 3 and 4. In this way, electrical terminals 90 are latchably secured in passageways 22 for removal therefrom by depression of lances 96 by conventional tool means to clear surfaces 32, if desired. Moreover, conductor-securing sections 94 of electrical terminals 90 are completely enclosed within housing 20. Pin contact sections 92 are surrounded and thus shielded and protected by front part 52 of shell 40.

Necked-down annular rear section 44 surrounds insulated portions of conductors 102 forwardly of braid 106 and forms an annular member over which braid 106 is then positioned. Ferrule member 60, which has been previously slidably positioned on cable 100 (and preferably prior to terminating the conductors), has a forward crimping section 62 which is just larger in diameter than shell rear section 44 with braid 106 thereon, and a rear crimping section 64 which is just larger in diameter than the outer diameter of cable 100 to be slidable thereon. Forward crimping section 62 is then moved forwardly along the cable and over braid 106 and controllably crimped onto annular rear section 44 to electrically connect braided shield 106 between forward crimping section 62 of ferrule member 60 and annular rear section 44 of shell 40 thereby forming an excellent mechanical and electrical connection. Rear crimping section 64 is preferably crimped to outer jacket 108 of cable 100 to secure the plug connector to the cable and form a strain relief for cable 100.

Cable guard member 70 is molded from a suitable plastics or elastomeric material and includes a shell-engaging section 72 and a cable-engaging section 74. Cable-engaging section 74 may, for instance, comprise a plurality of concentrically molded and connected rings of decreasing external diameter towards the rear end which are dimensioned to closely receive cable 100 therethrough as shown in FIG. 4. The rings serve to resiliently reinforce cable 100 from extreme lateral manipulation thereof. Cable guard member 70 is positioned onto cable 100 prior to positioning ferrule member 60 thereon and preferably prior to terminating the cable conductors. After shell member 40 has been secured in position on cable 100 via ferrule member 60, cable guard member 70 is moved along cable 100 with shell-engaging section 72 being positioned over ferrule member 60 and onto shell member 40 as shown in FIG. 4. The forward end 76 of cable guard member 70 should preferably coincide with forward face 24 of housing 20 within shell 40. Shell-engaging section 72 of cable guard member 70 preferably has an inside diameter selected to fit snugly on shell 40 after being manually forced thereover, and also preferably has a small projection 78 positioned and sized to fit into depression 48 of shell 40 to further assist in retaining cable guard member 70 on shell 40 and eliminate the need for adhesive material otherwise usable to retain cable guard member 70 in position.

Alternatively, if plug connector 10 is applied to a cable 100 in an appropriately equipped manufacturing facility, an insulative cable guard member may be molded over the finished plug connector/cable assembly. In the overmolding of such a cable guard, the forward end 76 of cable guard 70 is preferably coincident with forward face 24 of housing 20 within shell 40, and it is preferred that U-shaped channel 50 not extend as far rearwardly on shell 40 as forward end 76; thus the moldable insulating material will not flow into channel 50 which would be an undesirable situation. A one-piece metal shell would be somewhat easier to overmold than a two-piece shell.

As shown in FIGS. 3 and 4, an appropriate receptacle 200 comprises a dielectric housing 202 which is molded from a suitable dielectric material such as, for example, glass-filled nylon or the like, and it includes a terminal-receiving section 204 which is surrounded by a channel 206. A U-shaped recess 208 is located in terminal-receiving section 204 and is in communication with channel 206. Terminal-receiving passageways 214 extend through terminal-receiving section 204 in alignment with respective terminal-receiving passageways 22 in dielectric housing 20 of plug connector 10 and they include diametrically-opposed recesses in communication therewith. Electrical terminals 216 are disposed in terminal-receiving passageways 214 and are secured therein by lances 218 in engagement with stop surfaces (not shown) located within the passageways. Electrical terminals 216 have forked contact sections 220 which are located in the opposed recesses of the passageways and the free ends of contact sections 220 are provided with arcuate contact surfaces 222 on the inner surfaces thereof for wiping and spring electrical contact with pin contact sections 92 of electrical terminals 90 when the plug connector 10 is electrically mated with receptacle 200. Other contact sections 224 of electrical terminals 216 are disposed at right angles with respect to forked contact sections 220 and they extend through holes 226 in printed circuit board 228 for electrical connection with respective conductive paths 230, such as by solder connection therewith. Contact sections 224 can be in the form of compliant mounting sections such as those found on ACTION PIN (trademark of AMP Incorporated) terminal posts, for electrical connection with plated through-holes in the printed circuit board or the conductive paths.

A ground terminal is secured in receptacle 200, such as ground terminal 232, which is positioned within a recess 234 in housing 202 with a spring contact member 236 in the form of a cantilever beam extending into channel 206. Hook members 238 engage the top surface of support member 240 within channel 206. Legs 242 of ground terminal 232 are disposed in a bottom recess 244 with lances 246 of legs 242 in engagement with the rear surface of support 240 through an opening in the bottom surface of housing 202 in communication with channel 206, thereby latchably securing ground terminal 232 in position in housng 202 as shown in FIG. 4. In this way, the front portion 52 of metal shell member 40 forming the outer contact of plug connector 10 is electrically connected with spring contact 236 of ground terminal 232 when front shell portion 52 is positioned in channel 206 with U-shaped channel 50 being disposed in U-shaped recess 208 thereby polarizing plug connector 10 in receptacle 200. Ground terminal 232 has other contact sections 248 which extend through holes 250 in printed circuit board 228 for electrical connection to ground plane 252. Other ground terminal embodiments may be used such as are disclosed in U.S. Pat. No. 4,493,525.

As can be discerned, a DIN-type plug connector has been described which provides excellent EMI shielding. The plug connector has fewer parts and in easier to assemble and apply to a cable. An excellent mechanical and electrical connection between the shield of the cable and the outer contact of the connector is also provided. The plug connector of the present invention could be used with a shielded cable having only a single conductor, if desired.