GB2131234A - Multi-unit plug system - Google Patents

Abstract

Multi-unit plugs receive individual conductors and/or tape cables from industrial machines, and connect them to control circuitry on p.c.b.'s in one control frame, by insertion into standard sockets e.g. mounted on the p.c.b.'s. A plurality of plug units (one is shown) are mounted in an elongate housing 15 to form each plug, the cables from the plug units being guided through one recess (not shown) formed by abutting shell halves of the housing. Each plug unit includes a grooved cable clamp 35, 36 (fig. 9) which receives either a ribbon cable 20b' or parallel individual conductors 20y. A clip 31 is attached to each plug housing 15 at a selected one of a plurality of positions spaced along the housing 15, so that each plug housing may be inserted into only one of a plurality of 38 in a panel 10a of a frame, each clip 31 entering a corresponding notch 37 (fig. 48). Each clip 31 may similarly cooperate with a notch in an adaptor frame 30 (fig. 17) attached to a socket frame 14 and a p.c.b. 12 mounted on the frame. A complex polarised plug system may be built thereby from standard parts. <IMAGE>

Description

SPECIFICATION Multi-pin plug connection system for electronic control unit The present invention relates to electrical multi-pin plug connections and, more particularly, to a multi-pin plug connection system with a multi-pin plug connectorforthe connection of single or multiple unequally constituted multi-conductor cables of the round and/ or ribbon type to multi-terminal socket bars, particularlythe standardized socket bars of the printed circuit board modules of an electronic control unit.

Recent years have seen a great increase in the use of multi-conductor electronic transmission cables with multi-pin plug connectors, not only in the field of data processing hardware, but also in connection with modern industrial production machines, due to a very rapid growth in the volume of electronic data and electronic control signals which need to be transmitted between the control center of the production machine and the various points of control input and output on the machine.

Facilitating and forcing this trend is the realization that a centralization of the electronic control functions of a production machine in a control center and the useofacontrol computercan bring with itdecisive advantages in terms of a wider range of productive adaptation ofthe machine, as well as in terms of the ease with which the operational program of the machine can be adapted to changing production requirements.

This situation applies, for example, in the case of a modern injection molding machine, where the changeoverfrom the production of a one part to the production of another part may involve changes in a large number of control parameters on the machine.

The availability of prerecorded operating programs on interchangeable information ca rriers -- mag netic tape cassettes, for example-reduces a changeoverfrom one operational program to another to a problem-free routine task.

On the other hand, a production machine of thins kind will require rather complex electronic circuitry which, if malfunction occurs, may be difficult to service and to repair. The complexity of such servicing and repair work can be greatly reduced, however, through the application of the building-biock principle to the electronic control center, by using removable, readily exchangeable electronic circuitry modules with pluggable connections which may form part of a data bus,forexample.

While it is relatively easy to standardize the connec- tions between the various electronic circuitry modules at the data bus on the back panel ofthe control center, it is generally not possible to similarly standardize the plug connections for the connecting cables which lead from the control center to the various points of control input and output of the production machine. The particular-machine configuration may necessitate the use of an assortment of different cables, from round cables with only a few conductors to ribbon cables with several dozens of parallel conductors in a single cable.

Avariety of different multi-pin plug connectors, adapted to the multi-conductor cables in terms of type and size, are employed in a plug connection system which is known from the advertising brochure "Das Berg Backpanel-System" of Du Point de Nemou rs GmbH, Max-Plank-Str. 11, in 6047 Dietzenbach, Germany.

In the past, therefore, the various multi-conductor cables had different multi-pin plug connections at the back panel ofthe control center. The absence of uniformity in these connections reflects itself in correspondingly high production costs and in more difficult assembly operations, as well as in considerable space requirements, when a plurality of different multi-conductor cables have to have pluggable connections atthe same circuit board module.

Underlying the present invention is the primary objective of suggesting an improved multi-pin plug connection system with a multi-pin plug connector which permits a maximum degree of standardization of the pluggable electronic cable connections at the back panel of an electronic circuitry cabinet by serving as a plug terminal for single or multiple unequally constituted multi-conductor cables of the round type or of the ribbon-type, our a combination of cables of both types, and by presenting a compact standardized connector structure with easily assemblable components.

The present invention proposes to attain this objective by suggesting a plug connection system for the connection of the circuit board modules of an electronic control unitto the multi-conductor cables which lead to a production machine which is characterized by a plurality offractional-length plug units which are combinable to form a standardized contact bar assembly in the plug connector, which assembly is engageable into receiving walls in the form of a pocket between two shell halves ofthe plug connector housing, wherebythe plug units have clamping members with cooperating groove beds, and either ribbon cables or parallel oriented conductor strands of round cables are selectively clampable between positioning grooves ofthe groove beds.

In a preferred embodiment of the invention, the housing of the plug connector is a one-piece injectionmolded part, the shell halves ofthe plug connector being attached to the central housing pocket by means oftwo bending hinges. In the open, injection-molded state, the plug units and their attached round or ribbon-type cables are insertable into the housing pocket and the round cables are positionable between rows of studs in the two shell halves in such a way that 90 -reorientation bends are obtained.

As the shell halves are pivoted against each other, they engage the inserted plug units from behind with a retaining shoulder to secure them inside the housing pocket. At the same time, the shell halves close against each other in a snap action, forming a cable entry aperture on one longitudinal extremityforthe round andlorribbon cables.

The drawings originally filed were informal and the print here reproduced is taken from a later filed formal copy.

The subdivision of the pin bar assembly into a plurality of plug units makes it easier to assemble the plug connector and to locate connection defects or errors, if necessary. The combination of different multi-conductor cables in a single pluggableassembly is more compact than a comparable arrangement ofseparate plug connectors.

The standardized plug units are so designed that they require neither assembly tools norfasteners: The inner and outer clamping members are attachable to the ends ofthe conductor strands of round or ribbon-type cables in a snap-action operation, and a contact post housing with two rows of metallic contact posts is insertablethrough the attached clamping members, until locked in place in another snap action, thereby establishing electrical contact between the conductors and special dual knife ends of the contact posts.

The preferred embodimentfurther suggeststhe arrangement of a code clip on the outside wall ofthe central pocket ofthe connector housing, in one of a number of different locations, and the provision of an insertion aperture in the back panel ofthe control unit with a correspondingly located code recess.

As an alternative solution, a modified embodiment ofthe invention features an adapter frame with a code flange for each plug connector. The adapter frame is clamped to the socket bar atthe edge of a circuit board module to take the place ofthe back panel of the circuitry cabinet ofthe electronic control unit.

Further special features and advantages of the invention will become apparent from the description following below, when taken together with the accompanying drawings which illustrate, byway of example, preferred embodiments ofthe invention which are represented in the various figures as follows:: FIG. 1 shows, in a vertical transverse cross section, a circuitry cabinet of an electronic control center of a production machinewith atypical pluggablecircuit board module; FIG. 2 shows, as part of an enlarged detail of FIG. 1, a multi-pin plug connector embodying the present invention; FIG. 3 shows the multi-pin plug connector of FIG. 2 in a plan view; FIG. 4 shows the multi-pin plug connector of FIG. 2 in a side view in the direction of arrow B, without its multi-conductor cables; FIG. 5 is a transverse cross section through the plug connector of FIG. 2, taken along line V-V thereof, and likewise without the multi-conductor cables; FIG. 6 shows, as part of another enlarged detail of FIG. 1, portions of a data bus and of the multi-pin plug connectorofthe invention;; FIG. 7 shows the multi-pin plug connector of the invention in a further enlarged elevational side view, partially cross-sectioned along line VII-VII of FIG. 1; FIG. 8 is similar to FIG. 7, showing the end portion of circuit board module in a retracted position; FIG. 9 is similarto FIGS. 7 and 8, showing the multi-pin plug connector in a retracted position; FIG. 10 shows, in an elevational front view, a socket frameforthe multi-pin plug connectorofthe invention; FIG. 11 shows the socket frame of FIG. in a plan view; FIG. 1 2 shows the socket frame of FIGS. 10 and 11 in a transverse cross section, taken along line Xll-Xll of FIG. 1;; FIG. 13 is a transverse cross section of an adapter frame, taken along line Xlil-Xlil of FIG. 16; FIG. shows, in a plan view, an adapterframe forming partofthe modified multi-pin plug connector of FIGS.17 and 18; FIG. l5showsthe adapterframe of FIG.14 in a longitudinal cross section, taken along line XIV-XIV of FIG.16; FIG. 16 shows the adapter frame of FIGS. 13-15 in a plan view; FIG. 17 is a partially cross-sectioned elevational end view of a modified multi-pin plug connector, using the adapterframe of FIGS. 13-16; FIG. 18 shows the multi-pin plug connector of FIG.

17 in a partiallycross-sectionelevationalfrontview; FIG. 19 shows, in an elevational transverse cross section, the multi-pin plug connector of FIGS. 2-9, including a combination of different multi-conductor cables; FIG. 20 shows a front portion of the multi-pin plug connector of FIG. 19 in a longitudinal elevational cross section; FIG. 21 shows, at a furtherenlarged scale, a code clip, as seen in the direction of arrow E in FIG. 19; FIG. 22 shows the code clip of FIG. 21 in an end view; FIG. 23 shows the code clip of FIGS. 21 and 22 as seen in the direction of arrow F in FIG. 19;; FIG. 24 shows the code clip of FIG.23 23 in its mounted position in a cross-sectioned connector housing wall seen in the direction of arrow F in FIG. 19; FIG. 25 shows the code clip of FIG. 21 in its mounted position, as part of an end view in the direction of arrow E in FIG. 19; FIG. 26 shows, in a side view, the housing ofthe multi-pin plug connector in its injection-molded unfolded state; FIG. 27 shows the connector housing of FIG. 26 in a plan view; FIG. 28 shows the connector housing of FIGS. 26 and 27 in a closed position and transversely crosssectioned; FIG. 29 shows the connector housing of FIGS. 26 and 27 in an elevational view, as seen in the direction of arrow H in FIG. 30; ; FIG. 30 shows the connector housing in a plan view, as seen in the direction of arrow K in FIG. 26; FIG. is a transverse cross section through the connector housing, taken along line XXXI-XXXI of FIG.27; FIG. 32 shows, at an enlarged scale and crosssectioned along line XXXII-XXXll of FIG. 38, a contact post housing for a short plug unit ofthe multi-pin plug connector; FIG. 33 shows the contact post housing of FIG. 32 in a corresponding end view; FIG. 34 shows the contact post housing in a longitudinal cross section taken along line XXXIV XXXlVofFIG.38; FIG. 35 shows the contact post housing in a longitudinal cross section taken along line XXXV XXXV of FIG.38;; FIG. 36 showsthe contact post housing of FIGS.

32-35 in a bottom plan view; FIG. 37 is afrontal view ofthe contact post housing of FIGS. 32-36; FIG. 38 shows the contact post housing of FIGS.

32-37 in atop plan view; FIG. 39 shows, at a similarly enlarged scale and in a bottom plan view, an inner clamping memberfora short plug unit ofthe multi-pin plug connector; FIG. 40 shows the inner clamping member of FIG. 39 in an elevational view; FIG. 41 showsthe inner clamping member of FIGS.

39-40 in a top plan view; FIG. 42 shows the inner clamping member of FIGS.

39-41 in a transverse cross section taken along line XLll-XLIl of FIG. 40; FIG. 43 shows, at a similarly enlarged scale and in a bottom plan view, an outer clamping memberfor a short plug unit of the multi-pin plug connector; FIG. 44 shows the outer clamping member of FIG. 43 in an elevational view; FIG. 45 shows the outer clamping member of FIGS.

43-44 in a top plan view; FIG. 46 shows the outer clamping member or FIGS.

43-45 in an elevational end view; FIG. 47 shows the outer clamping member of FIGS.

43-46 in a transverse cross section taken along line XLVII-XLVll of FIG. 44; and FIG. 48 shows a portion ofthe back panel of the circuitry cabinet of FIG. 1 with coded apertures for multi-pin plug connector.

FIG. 1 shows, as part of an electronic control center for a production machine, a circuitry cabinet 10 enclosing a number of parallel spaced circuit board modules 12 in the form of printed circuitboardswhich carry various electronic components. The circuit board modules 12 are positioned and guided on opposite sides by module guides 11 at the upper and lower cabinetwalls 10. A positioning rail 25 in the center plane s-s ofthe circuitrycabinet engages a centering recess 12a' of a handle 12a on each module, thereby providing an accurately alignmentofthe circuit board moduleswithin the cabinet 10.

Each circuit board module 12 has on its rear edge a pluggable multi-conductorconnection,the connections above the center plane s-s being part of a data bus 18, and the connections below the piane s-s being the end points of a plurality of multi-conductor cables 20 and 20a which lead from the electronic control centertothevariousoperating units ofthe production machine, where control input and data outputtake place. The multi-pin plug connectors receiving the extremities of variously constituted cables 20 and 20' are the subject of the present invention and will be described in detail further below.

The data bus 18 serves to interconnect the various circuit board modules 12. Atypical data bus connection is shown at an enlarged scale in FIG. 6. It consists essentially of a socket bar 13 on the vertical edge ofthe printed circuit module 12 into which are engaged the contact pins 16b of a pin bar 16. The latter is carried by and electrically connected to the data bus 18 on the outer side of the back panel 1 Oa of the circuitry cabinet 10.

The back panel 1 0a has rectangular aperturesforthe pin bar 16, and the latter has shoulders positioning it againstthe back panel 10, through the intermediary of a centering member 17 which is clamped to the outer side ofthe back panel 1 0a by means of screws 24. The centering member 17 determines the position of the data bus 18 by means of positioning faces 17e and a plurality of flexible retaining noses 17a engaging the edges ofthe data bus 18.

The data bus 18 is secu red and stiffened by means of several data bus platens 19 which snap onto the edges ofthe data bus 18 through the action of flexible platen retaining noses 1 9b. The data bus platen 19 has a platen wall 1 9a extending parallel to the data bus 18 and bearing againstthe latter with spacer ribs 19c located between the conductors ofthe data bus, thereby stiffening the data bus 18. Enclosing the entire data bus assembly is a data bus cover 1 Ob.

The contact sockets 1 3b of the socket bar 13 are electrically connected to the printed conductors ofthe circuit board module 12 by means of a series of angled solder pins 13a,the extremities of the latter being soldered to the interior end portions of the contact sockets 13b, as can be seen in FIG. 9.

Identical socket bars 13 are arranged on the lower side of each circuit board module 12, where they are engageable bythe multi-pin plug connectors of the invention. All the socket bars 1 3a are so positioned in relation to the back panel 1 Oa that their outerfaces are approximately flush with the latter (FIG. 9). The socket bars 13 have two rows of contact sockets 1 3a of standardized dimensions and spacing.

Following is a description of a multi-pin plug connectorwhich is engageable into a socket bar 13 and which is adapted for attachment to the extremities of a variety of multi-conductor cables, both of the roundtypeandofthe ribbon type, wherebythe cables may be single or multiple cables. Additionally, the same plug connector is also adapted for attachment to a combination of both round and ribbon-type multiconductor cables.

In alignment with the lower socket bars 13 ofthe circuit board modules 12, the back panel 1 0a ofthe electronic circuitry cabinet 10 has a row of generally rectangular apertures 38 (FIGS. 9 and 48) through which a leading portion of the plug connector can reach into engagement with the socket bar 13. As can be seen in FIGS. 7 through 9,the contact pins 22b of the plug connector thereby penetrate the contact sockets 13b ofthe socket bar.

Guiding the plug connector during its engagement with the socket bar 13 is a socket frame 14 which, in the engaged position, produces an detent-type retaining action between its flexible retaining tongues 14a and the housing ofthe plug connector. The socketframe 14, which will be described in greater detail in connection with FIGS. 10 through 12, is attached to the outer side of the back panel 1 Oa, bearing against the latterwitha base flange 14b. Screws 24 provide the attachment (FIG. 6). A series of guide ridges 14e on the inner periphery of the socket frame 14 serveto guide the plug connector.

The major structural component of the multi-pin plug connector is a housing 15 which is injectionmolded of a resilient hight-polymer plastic. The connector housing 15 consists essentially of a hollow rectangular housing pocket 15a to the longitudinal upper edges of which are integrallyattachedtwo outwardly rectangular shell halves. The connection between the central housing pocket 15a and the two shell halves ofthe housing 15 is in the form of two bending hinges 15p.

In its original injection-molded state, the connector housing 15 has its shell halves oriented wing-like in a common plane, at right angles to the direction of plug engagement (FIGS. 27 and 29 through 31). In the course of assembling the plug connector, its shell halves are pivoted against each other until, in the closed position ofthe connector housing 15, the two shell halves close against each other in parallel alignment (FIGS. 1 through 9and 17 through 20).

The connector housing 15, when closed, forms a central joint line f-falong which the longitudinal end wall 1 5b of the shell halves touch. The longitudinal end walls 15b on one extremity ofthe housing 15 have recesses 32 and 33 accommodating therein a varied assortment of multi-conductor cables, for example, a number of round cables 20 and/or one or more ribbon cables 20' (FIGS. 1 and 2).

The recesses 32 and 33 are open towards the joint line f-f, forming a single cable entry aperture 0 of bilaterally branched outline in the longitudinal end walls 15b (FIGS. 4,17 and 28).The round cables 20 enter through six lobe-shaped recesses 32 in each housing half, the recesses in one housing half being offset againstthe recesses in the other housing half by one-halftheirspacing.The ribbon cables 20' enter through shallow recesses 33which extend overthe major portion ofthe length of the longitudinal end wall 15b and form a central rectangular entry slot atthe joint line f-f.

In the embodiment shown in the drawing (e.g. FIG.

4), the total transverse depth of the cable entry apertured is shown to betwicethediameterofa round cable 20 plus three timesthethickness of a ribbon cable 20'. Accordingly, it is possibleto connect upto three ribbon cables20'. The presence of one or more such ribbon cables helps to retain the round cables 20 in their respective recesses 32. In the absence of a ribbon cable 20' in the central recesses 33,the round cables20are prevented from shifting into adjacent or opposite recesses 32 by stem-like residual portions ofthe opposite shell end wall 1 5b which are facing each recess 32, as a result ofthe earlier-mentioned offset between opposite recesses.

The total transverse depth ofthe ribbon cable recesses 33 is less than the diameter of a round cable 20. The result is a compact, yet very adaptable, cable entry configuration attheshell end wall 15b.

The various multi-conductorcables 20 and 20' enter the connector housing 15 in a direction perpendicular to the direction of plug engagement. Therefore, all the cables needtobe reoriented insidethehousing 15 over an angle of 90 , into alignmentwith the direction of plug engagement. Awide ribbon cable 20' is preferably split into at least two cable strips 20a' and 20b' (FIG. 2).

Inside the connector housing 15, the cable strips are reoriented by offset diagonal cablefolds which form transitions between the edge-to-edge reoriented cable end portions and the overlying cable strips 20a' and 20b' in the cable entry aperture 0. The round cables 20 are simply bent over an angle of 90 , at appropriately staggered depths inside the connector housing 15, each cable 20 being separately held in place by a matrix of cable positioning studs 15i (see FIGS. 20 and 30).

The pocket 15a ofthe connector housing 15 holds two rows of contact pins 22b arranged to cooperate with the contact sockets 1 3b ofthe earlier-described socket bar 13 of a circuit board module 12 (FIG. 6). The contact pins 22b are part of a pin bar assemblywhich consists of either a single plug unit of a length matching the length ofthe housing pocket 15a, ortwo or more shorter plug units E (FIG. 20) having the same combined length.

All the plug units E have the same cross section. The lengths ofthe plug units E are preferably standardized in four sizes, so that either one, two, four, or eight identical plug units E make up a full-length pin bar assembly. Plug units of different length may be used to make up a pin bar assembly. For example, in FIG. 20 can be seen two plug units E of one-eighth length adjoined buy a plug unit of one-quarter length.

The pin bar assembly, consisting of one or more plug units E with attached conductors ofthe several multi-conductorcables 20 and/or20', is inserted into the housing pocket 15a, when the housing 15 is in the open, unfolded state (FIG. 30). Inside the housing pocket 15a,the plug units E are guided and longitudinally positioned by means of dovetail guides, consisting of a series of dovetail grooves 150 (FIG. 30) on the inner longitudinal sides ofthe pocket 15a and one or more matching dovetail keys 34a (FIG. 36) on the sides of each plug unit E.

A pair of positioning shoulders 15g on the longitudinal walls ofthe housing pocket 15a determines the insertion position ofthe plug units E by engaging the end faces ofthe dovetail keys 34a. Unequally sized dovetail grooves 150 on the two longitudinal walls of the housing pocket 15a and matchingly unequal dovetail keys 34a on the plug units E preclude the accidental insertion of a plug unit E in the wrong orientation.

Following insertion ofthe plug units E into the pocket 1 5a, the two shell halves ofthe connector housing 15 can be closed by pivoting them about their bending hinges 1 5p, with the resultthat inwardly protruding retaining shoulders 15k on the two shell halves engage edges on the back sides of the plug units E, thereby clamping the latter against the positioning shoulders 15g ofthe housing pocket 15a (FIGS. 9 and 31).

Intheclosed position oftheconnectorhousing 15, the two shell halves are held together by means of flexible locking noses 1 sic on the distal edge of one shell halfwhich engage matching locking recesses 1 5d on the distal edge ofthe other shell half (FIGS. 3,5 and 30). The two shell halves are centered in relation to each other by means of several centering pins 15t in one shell half engaging centering bores 1 5n in the other shell half(FIG. 30).

Any plug unit E and its attached multi-conductor cable, orcables, can be removed from the plug connector assembly by simply opening the shell halves ofthe connector housing 15 and by sliding the plug unit out of the housing pocket 1 5a, without thereby disturbing the other plug units and their attached cables.

Itfollows that, by connecting each ribbon cable 20' to a separate plug unit E, it is possible to effortlessly remove or replace the entire cable, together with the attached plug unit, withoutthe need for breaking the electrical connections between the conductors ofthe cable and the contact pins 22bofthe plug unitE. In the case of round cables, which normally have fewer conductors, it may be advantageous to group two or more cables with a single small plug unit.

The component parts of a typical plug unit E are shown in FIGS. 32 through 47. Each plug unit consists offourelements: acontact post housing 34, shown in FIGS. 32 through 38, an inner clamping member 35, shown in FIGS. 39 through 42, and outer clamping member 36, shown in FIGS. 43 through 47, and a series of metallic contact posts 22, shown in FIGS. 6 through 9 and 19.A novel structure of such a contact post and a novel method of manufacture are disclosed and claimed in mycopending British PatentApplication No. filed In the assembled condition of a plug unit E (FIG. 20), the strands 20y of a multi-conductor cable 20 or 20' are held in parallel alignment and at a regulartransverse spacing in positioning grooves 35e and 36e of the inner and outer clamping members 35 and 36, respectively, as a pair of outwardly extending flexible retaining hooks 35c on the extremities the inner clamping member 35 engages corresponding retaining noses 36c on the extremities ofthe outer clamping member 36 (FIGS. 20,40 and 44).A pair of inwardly extending flexible retaining hooks 359 on the extremities of the inner clamping member 35 cooperate in a similarfashion with retaining noses 34b ofthe contact post housing 34to attach the two clamping members to the housing (FIGS. 20,35 and 40).

The assembly of a plug unit E and the establishment ofthe necessary electrical connection between each conductor and a contact post 22 involvesfirstthe snap-action attachment ofthe inner and outer clamp- ing members 35 and 36 to the extremities ofthe insulated conductor strands 20y. The upstanding flexible retaining hooks 35c ofthe inner clamping member thereby provide guidance in cooperation with matching guide grooves in the end faces ofthe outer clamping member 36, priorto latching onto the retaining noses 36c ofthe latterlFIGS. 20 and 44).

In the case of a ribbon cable, the spacing between its conductor strands 20y' corresponds to the spacing of the positioning grooves 35e and 36e, and there is therefore no need to separate the conductor strands.

In the case of round multi-conductor cables, it is necessary to expose an end portion of each conductor strands 20y by removing a length portion ofthe cable sheath. The strands 20y are then positioned side-byside on the groove bed 35a ofthe inner clamping member 35, the correct alignment and spacing being established by the cooperating positioning grooves 35e and 36e ofthe inner and outer clamping members 35 and 36, respectively.

In orderto improve the clamping effect of the two clamping members 35 and 36 on the conductor strands 20y or 20y',their positioning grooves 35e and 36e have a V-shaped cross section, giving the groove beds 35a and 36f ofthe clamping members a sawtooth-shaped profile. The depth ofthe positioning grooves 35e and 36e is such that the combined profile ofthetwo groove beds, in the clamped position, provides sufficient space for the webs between the conductor strands of a ribbon cable. The resultant concentration of the clamping pressure in four points on the circumference of the conductor strands improves the strand-holding action, by producing a localized deformation ofthe conductor insulation.

The central reinforcing ribs 35b and 36a on the backs ofthe two clamping members 35 and 36 stiffen the latterto such an extend that, even in the case of a long plug unit, the middle portions ofthe clamping members exert some clamping pressure on the conductor strands. It should be noted that long plug units are normally only employed in conjunction with ribbon-type multi-conductor cables.

The contact post housing 34 has two rows of pin slots 34c extending through its body at twice the longitudinal spacing of the positioning grooves and of the conductor strands, each pin slot holding a metallic contact post 22 with a outwardly extending contact pin 22b. Each contact post 22 also has an inwardly protruding length portion with dual contact knives 22a.

The inner and outer clamping members 35 and 36 have on opposite sides of their longitudinal center plane two dual rows of guide slits 35d and 36b, respectively. The spacing of these guide slits corres ponding to the longitudinal spacing ofthe pin slots 34c in the contact post housing 34. The guide slits 35d and 36b are so arranged thatthey intersect every second positioning groove 35e and 36e in the groove beds 35a and 36f of the two clamping members.In addition, the dual rows ofguide slits 35d and 36b on one side ofthetwo clamping members are longitudinally offset by one-halftheir longitudinal spacing from those on the other side, so that successive positioning grooves 35e and 36e ofthe two clamping members are alternatingly intersected by dual guide slits 35d and 36b on opposite sides ofthe clamping members 35 and 36, respectively.

When the preassembled inner and outer clamping members 35 and 36 are brought into engagement with the contact post housing 34, the dual contact knives 22a of the metallic contact posts 22 penetrate the dual guide slits35d and 36b ofthetwo clamping members 35 and 36, thereby also penetrating and partially displacing the insulation ofthe conductor strands 20y or 20y' which occupythe positioning grooves 35e and 36e ofthe clamping members. In the process,thedual contact knives 22a establish an electrical connection between the conductive wires of the multi-conductor cable, or cables, held by the clamping members 35 and 36 and the contact pins 22b. As the dual contact knives 22a advance into the guide slits of the outer clamping member36,theyarefurtherguided and at the same time forcibly closed against the wires of the conductor strands (FIG .6).

The engagement ofthe two clamping members 35 and 36 againstthe contact post housing 34 thus automatically establishes permanent and secure elec trical connections between the conductors ofthe cable and the contact pins 22b ofthe plug unit E. The engagement movement is guided in the transverse sense by a central reinforcing rib ofthe inner clamping member 35 which engages a matching central slot 34f ofthe contact post housing 34. Guidance in the longitudinal sense is provided bythe inwardly extending retaining hooks oftheclamping member35 which engage guide grooves in the end faces ofthe housing 34. The engaged position is maintained by the retaining hooks 359 latching onto retaining noses 34b in said guide grooves (FIGS. 20 and 35).

The above-described plug unit E thus lends itself ideally for mass production, while requiring minimal skills for its assembly: Following the insertion of two banks of contact posts into the contact post housing, the injection-molded clamping members and contact post housing are forcibly snapped together, in the process automatically establishing the necessary electrical connections.

Finally, the assembled plug units E are inserted into the pocket 15a ofthe connector housing, the attached multi-conductor cables are reoriented inside the shell halves ofthe housing in the direction ofthe entry aperture 0, and the connector housing is closed and snapped shut.

It will be noted thatthe plug connector ofthe invention is assembled and electrically connected to variously constituted multi-conductor cables without employing any screws, rivets, adhesive joints, or solder. While special tools may be required to remove and disconnect a multi-conductor cable from its plug unit E an operation which is not recommended and normally not necessary for servicing - no tools are required to open the plug connector housing and to removeanyoralloftheplug unitsEandtheirattached cables.

Asimple mechanical code system assures that each plug connector ofthe electronic control unit can only be inserted into the contact bar 13 of its assigned circuit board module 12. Such a code system is achieved by attaching to each plug connector a small code clip 31 (FIGS. 21 through 25) in such a way that the location ofthe code clip 31 on the connector housing represents the code information. A matching code recess 37 on the periphery of the rectangular aperture 38 in the back panel 1 Oa ofthe circuitry cabinet 10 (FIGS. 9 and 48) "reads" the code, blocking the insertion of any plug connectorwith a code clip in a different location.

FIGS. 2, 5,7 through 9 and 19through 25 show a code clip attached to a longitudinal wall of the central pocket 1 5a of the connector housing 15. For this purpose, the housing pocket 15a has arranged on the outer edge of each of its four sides numbered rectangular dovetail recesses 15f (FIG.2 and 26). By providing eight dovetail recesses on each ofthe two long sides and one on each of the two short sides of the pocket 15a, it is possible to obtain eighteen different positions ofthe code clip 31, for example.

FIG. 48 shows a pattern of code recesses 37 in a row of back panel apertures 38.

In the example herein illustrated and described, each plug connector carries only one code clip 31, and each aperture 38 has only one code recess 37 on its periphery. It should be understood, of course,that it is also possible to use two or more code clips on each plug connector and a corresponding number of matching code recesses in the apertures, if it is desired to have a larger number of different code configura- tions.

Fig. 25 shows the shape of a dovetail recess 15f in the wall ofthe housing pocket 15a forthe attachment of a code clip31. In a circumferential shoulder ofthe housing pocket pocket 15a, opposite its earliermentioned inner positioning shoulder 15g and aligned with the dovetail recesses 15f, are an equal number of locking recesses 15m.

The code clip 31 has a central shaft portion 31 c of generally trapezoidal cross section (FIGS. 21 through 23). On its outer extremity, it has a flexible dovetail key 31 bwhich cooperates with the dovetail recess 15f of the housing pocket 15a to produce a wedge action by which the dovetail key 31 b is resiliently deformed and held againstthe wall ofthe pocket 15a, when the code clip 31 is inserted into the dovetail recess 15f. On its inner extremity, the clip 31 carries a locking nose 31 a which, when engaged into the locking recess 15f ofthe housing pocket 15a, secures the code clip 31 in place.

In this position, an inner end face ofthe dovetail key 31 b abuts againstthe bottom of the dovetail recess 15f.

In their engaged position, the plug connectors are initially held in position by the flexible retaining tongues 14a oftheirsocketframes 14which cooperate with a pair of laterally protruding retaining noses 15h on each side ofthe connector housing 15 (FIGS. 7 through 9). The retaining tongues 1 4a provide a detent action, spreading apart when a plug connector is disengaged from the socket bar 13. Two dorsal handle portions 1 5e on each connector housing 1 facilitate the disengagement action.

After engagement of all the plug connectors into their socket bars 14, acrosstheircoded apertures 38 in the back panel 1 Oa, the plug connectors are positively secured by means of a central locking rail 23 (FIGS. 1,2 and 8) which engages a central recess 15e' between the two dorsal handle portions 1 5e ofthe plug connectors. The locking rail 23 is similarto the positioning rail 25 for the circu it boa rd modules 12 (FIG. 1). Both rails are removably attached to thewalls ofthe electronic circuitry cabinet 10.

Thus, it is also possible to pull a circuit board modules 12 from the circuitry cabinet, without removing the associated plug connector, by first removing the positioning rail 25 on the forward side ofthe cabinet 10, and then pulling the module 12 forward, thereby simultaneously disconnecting its socket bars 13 from the data bus 18 and from the plug connector, while both ofthem are held in place by the back panel 1 0a. This disconnecting operation is shown in FIG. 8.

The handle 12a on the forward edge ofthe circuit board module 12 (FIG. 1) facilitates the operation.

It will be noted that, with the exception of the positioning rail 25 and the locking rail 23, which are attached to the cabinet side wall by means of threaded fasteners, no tools are needed to remove and/or access the serviceable components ofthe electronic control center.

In a modified embodimentoftheinvention, illus trated in FIGS. 13 through 18,the novel plug connector ofthe present invention is attached directly to the socket bar 13 ofthe circuit board module 12 and supported exclusively by the latter, without the intermediary of the back panel 1 Oa of the circuitry cabinet 10.

This is accomplished with the aid of an adapter frame 30 taking the place of the back panel 1 Oa, the frame 30 being clamped to the socket bar 13 on the circuit board module 12. The adapterframe 30 serves as a supportforthe socket frame 14which is described further above in connection with FIGS. 6 through S and 1 0through 12, and it also serves as a coded receiving memberforthe coded connector housing 15.

As can be seen in FIGS. 14through 16, the adapter frame 30 is a rectangularframe with an outline similar to that ofthe socket frame 14. Near its extremities, it has two screw holes 30e in alignment with the screw holes 14e of the frame 14. Linked to the extremities by means of hinge connections 30i aretwo clamping tabs 30h with screw holes 30e'. After being pivoted inwardly, as shown in FIG. 18, the clamping tabs 30h extend behind the extremities ofthe socket bar 13 with clamping paws 30m which cooperatewith interior shoulders 30tto clampthe socket bar 13.

The two screws 24' which clamp the adapterframe 30 to the socket bar 13 also serve to attach the socket frame 14to the adapterframe 30, taking the place of the screws 24 of FIG. 6, lower half. An accurate alignment between the two frames is obtained by means of centering pins 30f in the four corners of the adapterframe 30 which engage matching centering holes (not shown) in the socketframe 14. The tap holes 14e of the socket frame 14 (FIG. 10) have square length portion to facilitate the self-tapping engagement of the screws 24.

For coding purposes, the adapter frame 30 has an inwardly protruding code flange 30b with an opening matching the dimensions ofthe housing pocket 15a of the plug connector. The opening ofthe code flange 30b thereby simu lates the apertu re 38 of the back panel 1 0a (FIG. 48). In orderto simplify the establishment ofthe code in the adapterframe 30, the code flange 30b has eighteen knockout recesses 30d in alignment with the eighteen dovetail recesses 15f of the connector housing 15 and with the eighteen recesses 14d ofthe socket frame 14. The knockout recesses 30d are marked with numbers 309.

The arrangement of knockout recesses in the code flange 30b makes it possible to produce the desired code recess 30b' in any one ofthe eighteen position by simply breaking out the knockout portion of the selected recess 30d. FIG. shows an engaged plug connector with a code clip 31 reaching through a recess 14d of the socket frame 14 and through a code recess 30d' ofthe adapterframe 30.

The use of an adapterframe 30 in the place of the back panel 1 0a of a circuitry cabinet for positioning and code-reading purposes is advantageous in connection with circuit board modules 12 which have to be located outside the central electronic control unit of the production machine.

FIGS. 2,19 and 20 show a multi-pin plug connector with a plurality of plug units E having six round cables 20 and two ribbon cables 20' attached thereto. The round cables 20, having only two conductors 20y each, are attached to two one-eighth-length plug units E with six positioning grooves 35e and 36e in their clamping members 35 and 36, respectively.

In view ofthe close longitudinal spacing of the positioning grooves and the considerably greater diameter ofthe sheaths ofthe round cables 20, the attachments of the conductor strands 20yto the plug unit E are preferably laid out in such a way that the conductor strands 20y of successive cables enter the positioning grooves 35e/36e alternatingly from opposite sides, as can be seen in FIG. 20. There,thisfeature is illustrated by showing only those conductor strands 20y cross-sectioned in the positioning grooves 35e/ 36e which belong to the three round cables 20 in the shell halfwhich remains on the cross-sectioned plug connector assembly.

Accordingly, the conductor strands ofthefirsttwo cables are shown to be clamped in grooves No. 1,2,5 and 6 ofthe first plug unit while the conductor strands ofthe third cable are clamped in grooves No. 3 and 4 of the second plug unitE. Correspondingly, the first of the three round cables in the opposite shell half has its conductorstrands clamped in grooves No.3 and 4 of the first plug unit, while the second and third cables on that side havetheirconductorstrands clamped in grooves No.1,2, and 6 of the second plug unit.

A proximate length portion ofthe round cables 20 on each side of the plug units E extends transversely to the pin barassemblyformed bythe sum ofthe plug units E, in approximate alignment with the positioning grooves 35e and 36e ofthe clamping members 35 and 36. This alignment is maintained by means of a matrix of cable positioning studs 1 5i in the two shell halves of the connecter housing 15 (FIG. 30). As can be seen in FIG. 20, the cable positioning studs 15i also serves produce and maintain longitudinal and transversely staggered reorientation bends between the transversely oriented proximate length portions and longitudinally oriented entry portions of the cables 20.

The rectangular dimensions of the cable positioning studs 15i are such that the spacing between adjacent studs in either direction is somewhat smallerthan the diameter ofthe round cables 20, and the studs 15i have sharp corners-with which they tend to bite into the sheaths ofthe cables 20, especially in the area of their reorientation bends, thereby also providing a effective strain-relieffunction for the conductor strands.

As can be seen in FIGS. 19 and 30, the longitudinal rows of cable positioning studs 1 5i in the two shell halves are offset from each other by one-halfthe spacing between rows to align the longitudinal cable length portionswiththe rounded recesses 32 of the cable entry opening 0 (FIG. 30). These recesses are likewise narrowerthan the diameter of the round cables 20 to produce a slight deformation ofthe inserted cables.

The pivotability ofthe shell halves ofthe connector housing 15 about their bending hinges 15p assures an effortless and convenient assembly operation, both shell halves being fully accessible forthe insertion and bending of a set of round cables.

The two strips 20a' and 20b' ofthe ribbon cable 20' may be connected to one or several plug units E. Their conductor strands may enter the plug units from the same side, orfrom opposite sides, as shown in FIG. 19, for example. The plug units Ewith attached ribbon cable strips are inserted into the pocket 1 5a of the connector housing 15 foliowing the insertion of the round cables 20. In orderto reorient the ribbon strips from their proximate transverse orientation to the longitudinal orientation, they are given a diagonal fold, as shown in FIG. 2. The diagonal folds ofthe cable strips 20a' and 20b' are staggered in the longitudinal sense, but not in the transverse sense, so that the cable strips extend through the cable entry aperture 0 in an overlying relationship.

Numerous advantages of the multi-pin plug connec tor ofthe invention are obvious from the foregoing description, among them the need for very few parts, all ofthem - except for the metallic contact posts injection-molded, the simplicity of making the electrical connections and assembling the parts and, last but not least, the capability of connecting variably constituted combinations of multi-conductor cables to a standardized socket bar of a circuit board module.

Is should be understood, of course,thattheforegoing disclosure describes only preferred embodiments ofthe invention and that it is intended to cover all changes and modifications of these examples of the invention which fall within the scope ofthe appended claims.

Claims (28)

1. A plug connection system for the connection of the control elements of an electronic control unit to the multi-conductor cables which lead to a production machine, wherein the control unit includes standar dized carriers (e.g. circuit boards) carrying the electro nic components, the carriers being arranged in alignment with each other and equipped with contact bars on their outer edges, and wherein socket frames are arranged on the outer side ofthe back panel ofthe control unit in the area of apertures, forthe insertion of multi-conductor plug connectors into engagement with the contact bars of the carriers in accordance with an insertion code, the cables having their conductor strands inside the plug connectors engaged by rows of contact knives which are secured in a housing, characterized in that a plurality of plug units (E) are combinabletoformastandardizedassemblyinthe plug and have clamping members (35,36) with cooperating groove beds (35a, 36f) and that, selectively, ribbon cables (20') or parallel oriented conductor strands (20y) of round cables (20) are clampable between positioning members (positioning grooves 35e, 36e) of said groove beds (35a, 36f), and that the plug units (E) are securable inside receiving walls (pocket 15a) of two housing shell halves (15) ofthe plug, whereby the cables (20,20') enterthe housing shell halves (15) through recesses (32,33) of abutting end walis (1 5b) of the shell halves (1 5).

2. A plug connection system in accordance with Claim 1, characterized in thatthe housing shell halves (15) have a rectangular outline and that the recesses (32,32) form a cable entry apertures (0 in Figs. 4,7,28) along a central housing joint (f-f) between adjoining edges ofthe end walls (15b) ofthe shell halves and in parallel alignment with the direction of plug engage ment, and the rounded recesses (32) forthe round cables (20) in one shell half (15) are offset in relation to the rounded recesses (32) in the other shell half (15) in the direction of plug engagement.

3. A plug connection system in accordance with Claim 2, characterized in that the maximum depth (t) ofthe cable entry aperture (0) corresponds to twice the diameter of a round cable (20) plus three times the thickness of a ribbon cable (20').

4. A plug connection system in accordance with one of Claims 2 or3, characterized in that the cables (20,20') extend perpendicularly to the direction of plug engagement in the area ofthe cable entry aperture (0) and are reoriented over an angle of 90" on the inside ofthe plug,wherebythe ribbon cables (20') are sliced into cable strips (20a', 20b' in Fig. 2, 19) which, as a result of a diagonal fold, overlap each other in the cable entry aperture (0).

5. A plug connection system in accordance with one ofthe preceding claims, characterized in that the shell halves (15) of the housing and its retaining walls (1 5a) are integral portions of an injection-molded part, whereby the shell halves (15) are attached to the pocket (15a) by means of bending hinges (15), extending in opposite directions from the pocket (15a) in a plane which is perpendicular to the direction of plug engagement (injection-molded position perfigs.

26,27,29-31) and, in the course of assembly, are pivoted against each other into a position (assembly positon per Figs. 1-9, 17-19,28) in which they extend parallel to the direction of plug engagement.

6. A plug connection system inaccordancewith one ofthe preceding claims, characterized in thatthe plug units (E)which are positioned in a row inside the housing pocket (15a) have uniform cross sections and a standardized length which is one-eighth, onequarter, orone-half of, or identical to,the interior length ofthe housing pocket (1spa).

7. A plug connection system in accordance with one of Claims 5 or6, characterized in that the shell halves (15) create a positive retaining action on the plug units (E) between shoulders (15k, 15g) ofthe shell halves (15) and of the pocket (15a), respectively, when the shell halve (15) are pivoted from their injectionmolded, open position to their assembled, closed position.

8. Aplug connection system in accordance with one of the preceding claims, characterized in that each ofthe plug unit (E) is attachable to the housing pocket (1 5a) by means of dovetail connections of which the dovetail keys (34a, 34a') are arranged on the outer longitudinal walls ofthe plug Units (E) and the cooperating dovetail grooves (150) are arranged on the inner longitudinal wall ofthe pocket ( 1 5a), the end faces of the dovetail keys resting against a shoulder (15g).

9. A plug connection system in accordance with Claim 8, characterized in thatthe dovetail connections on one side ofthe pocket(15a) and plug units (E) are larger in dimensions than the dovetail connection on the opposite side.

10. A plug connection system in accordance with one ofthe preceding claims, characterized in thatthe shell halves (15),when pivoted from their injectionmolded position to their assembled position, are centered in relation to each other by means of centering pins (1 5t) in one shell half and cooperating centering bores (15n) in the other shell half, and that, in the closed position, the shell halves (15) are releasably locked together by means of flexible shell closure latches (15c) on one shell half engaging locking recesses (15d) on the other shell half.

11. A plug connection system in accordance with one ofthe preceding claims, characterized in that the parallel conductor strands of the cables (20,20') are positioned and clamped at a regular spacing between strands by positioning grooves (35e, 36e) of matching groove beds (35a, 36f) of two clamping member (35, 36), whereby the flexible retaining hubs (35c, 35g) of the inner clamping member (35) engage the outer clamping member (35) and a housing (34) for the metallic contact posts (22) in a snap action (Figs. 6-9, 19,20; 40,41,43,44).

12. A plug connection system in accordance with Claim 11, characterized in that the housing (34) accommodates axially secured metallic contact posts (22) with contact pins (22b) which are engageable with contact sockets (13b) of a contact bar (13) and which are electrically connected to the conductor strands (20y) ofthe cables (20,20') in the groove beds (35a, 36f) by means of contact knives (22a), (Figs. 6-9, 19).

13. A plug connection system in accordance with with one of Claims 11 or 12,characterized in thatthe housing (34) is centered in relation to the inner clamping member (35) by means of a central longitudinal reinforcing rib (35b) ofthe innerclamping member (35) which reaches into a central slot (34f) of the housing (34).

14. A plug connection system in accordance with one ofthe preceding claims, characterized in that each module (12) is equipped with two contact bars (13) on opposite sides of a center plane (s-s), the contact bars (13) on one side ofthe center plane (s-s) being engageable by the plug units (E) ofthe cables (20,20'), and the contact bars (13) on the other side ofthe center plane (s-s) being in contact with a data bus (18) through the intermediary of a pin bar (16), the data bus (18) being attached to the outside of the back panel (1 0a) by means of centering members (17)with retaining noses (17a).

15. A plug connection system in accordance with Claim 13, characterized in that the data bus (18) is arranged under a data bus cover (1 Ob) ofthe circuitry cabinet (10) and stiffened by means of data bus platens (19) while abutting against positioning faces (17c) of the centering member(17).

16. A plug connection system for the connection of the control elements of an electronic control unit to the multi-conductor cables which lead to a production machine, wherein the control unit includes standardized carriers (e.g. circuit boards) carrying the electronic components, the carriers being arranged in alignment with each other and equipped with contact bars on their outer edges, and wherein socket frames are arranged on the outer side of the back panel of the control unit in the area of apertures, forthe insertion of multi-conductor plug connectors into engagement with the contact bars of the carriers in accordance with an insertion code, wherein the plug connectors comprise a row of standardized plug units (E) inside of which the conductor strands of the cables are attached and engaged by rows of contact knives which are secured in a housing, particularly in accordance with one of Claims 1 through 15, characterized in that each plug connector has a number of attachment positions (dovetail recesses 15f; locking recesses 1 Sm) in a housing portion reaching through the back panel (10a) ofthe circuitry cabinet (10), and that a code clip (31) is removably attached to a selected one of the attachment positons ofthe connector housing, forthe establishment of an insertion code, the location ofthe selected attachment position corresponding to a code recess (37) in an insertion aperture (38) oftheback panel (lOa).

17. A plug connection system in accordance with Claim 16, characterized inthatthecodeclip(31) is attached to a wall of the housing pocket (1 5a) which holds the plug units (E), that the housing wall is parallel to the direction of plug engagement, and that the attachment is in the form of a dovetail connection.

18. A plug connection system in accordance with one of Claims 16 and 17, characterized in that the code clip (31) includes a flexible dovetail key (31 b) of which the upper end face abutsagainstthe bottom of a dovetail recess (15f) in the wall ofthe housing pocket (15a), and that the code clip (31) includes a locking nose (31 a) with which it engages behind the wall of the pocket (15a) in the area ofthe locking recess (1 Sm), (Fig.7,9,19).

19. A plug connection system in accordance with one ofthe preceding claims, characterized in that the socket frames (14) have flexible retaining tongues (14a)with which they maintainthe plug connectors in their engaged position by engaging retaining noses (1 soh) on the sides ofthe connector housing (15).

20. A plug connection system in accordance with one of the preceding claims, characterized in thatthe housing shell halves (15) and the modules (12) have arranged on their respective back sides handles (15e; 12a)with a central recess (15e'; 12a') receiving transversely extending rails (23,25) which are removably attached to the cabinet (10), (Figs. 1,27,30).

21. A plug connection system forthe connection of the control elements of a printed circuit board equipped with contact bars on its outer edges to the multi-conductor cables which lead to a production machine, wherein a multi-conductor plug connector is insertablethrough a socket frame, in accordance with an insertion code, to engage a contact bar of the printed circuit board, and the plug connector comprises a row of standardized plug units (E) inside ofwhich the conductor strands of the cables are attached and engaged by rows of contact knives which are secured in a housing, characterized in that the socket frame (14) is attached to the circuit board (12) by means of an adapterframe (30), and that a code clip (31) which is selectively and removable attachable to one of a number of attachment locations at the pocket (1 5a) of the housing shell halves (15) is arranged to cooperate with a selected code recess (30d' in Figs. 13-18) in an interior code flange (30b) ofthe adapterframe (30), (Figs.13-18).

22. A plug connection system in accordance with Claim 21, characterized in that the codeflange (30b) of the adapterframe (30) has arranged on its circumfer ence a number of knockout recesses (30d) (Fig. 16, numbers 1-18), one of the knockout recesses (30d) being transformable into a code recess (30d') in a location corresponding to the location ofthe code clip (31), by breaking out the residual wall ofthe knockout recess (30d).

23. A plug connection system in accordance with one of Claims 21 or 22, characterized in that the adapterframe (30) is engaging the contact bar(13) of the printed circuit board (12) by means of clamping members (30h) which are attached to the adapter frame (30) by means of bending hinge connections (30i).

24. A plug connection system in accordance with one of Claims 11-23, characterized in that the positioning grooves (35e, 36e) form positioning channels of square cross section with horizontal and vertical diagonals (Figs. 40,44,20).

25. A plug connection system in accordance with one ofthe preceding claims, characterized in thatthe printed circuitboard (12) and the plug connectors are centered on their back sides by means of rails (23,25) positioning them on one point only.

26. A plug connection system in accordance with one of Claims 11 or 12, characterized in that clamping member (35,36) define a small clearance between their groove beds (35a, 36f) and that, in the engaged position ofthe retaining hooks (35c), the positioning grooves clamp the conductor strands (20y) of the cables (20,20') under partial deformation of the insulating sheaths.

27. A plug connection system in accordance with one ofthe preceding claims, characterized in thatthe longitudinal length portions of the round cables (20) which extend perpendicularly to the direction of plug engagement are individually secured in the two shell halves (15) by means of cable positioning studs (15i) so as to provide a strain reliefforthe attached conductor strands of the cables (20), wherebythe longitudinal length portions in one shell half are offset from the longitudinal length portions in the other shell half in the direction of plug engagement, and thatthe ribbon cables (20') and the conductor strands (20y) of the round cables (20) in the two shell halves enter the positioning grooves (35e, 36e) of the clamping members (35,36) ofthe associated plug units (E) from opposite sides (Figs. 19,20).

28. A plug connection system constructed and arranged to operate substantially as herein described with reference to and as illustrated in any ofthe Figures ofthe accompanying drawings.