Abstract:
A multipolar plug-in connection, wherein at least one partially cylindrical metal shell is provided on the connector and accompanying outlet or coupling. A contact spring element is also provided on at least one longitudinal edge of at least one of the partially cylindrical shells. When the plug-in connection is made correctly, the element establishes a contact with the longitudinal edge of adjacent partial cylinder shells in the direction of the periphery.

Description:
BACKGROUND OF THE INVENTION 
     This application is the National phase under 35. U.S.C. § 371 of PCT International Application No. PCT/EP99/07843, which has an International filing date of Oct. 15, 1999, which designated the United States of America. 
     The invention relates to a multipole plug-and-socket connection according to the preamble of the main claim. 
     Plug-and-socket connections of this kind are known. (Main catalogue of the firm W. W. Fischer SA, Switzerland, 1997 edition). For easy position location when assembling the plug and socket or coupling, either metal semicylindrical shells are to be provided both at the plug and at the socket/coupling, these complementing one another when correctly assembled to form a complete cylinder surrounding the plug-and-socket connection, or, if the intention is to prevent structurally similar plug-and-socket connections from being confused, a plurality of part-cylindrical shells distributed over the circumference are to be provided, for example two quarter-cylindrical shells at the plug and two quarter-cylindrical shells at the socket/coupling (Fischer Catalogue, Section L, page 4: Codings for position location when plugging in). 
     In order to make plug-and-socket connections of this kind EMC-tight, a metal plug housing is used which on the one hand is electrically connected to the cable screening and which establishes electrical contact with the housing, also consisting of metal, of the socket or coupling when assembled. This earth contact, previously only possible via the plug housing, for the cable screening is complex and not optimum in electrical terms. 
     The object of the invention is therefore to develop and improve a multipole plug-and-socket connection of the indicated type so as to achieve optimum earth contact between the plug and the socket or coupling both in electrical and mechanical terms. 
     SUMMARY OF THE INVENTION 
     Taking a multipole plug-and-socket connection according to the preamble of the main claim as a starting point, this object is solved by the characterising features of this claim. The subclaims comprise advantageous developments. 
     According to the invention, the metal part-cylindrical shells, which are in any case provided in plug-and-socket connections of this kind for mechanical position location, are modified in a simple and inexpensive manner so as to be simultaneously used to establish electrical earth contact. At least one additional contact spring element is formed for this purpose at least at one of the longitudinal edges of at least one of the part-cylindrical shells, this element establishing electrical cross-contact between the longitudinal edges of the part-cylindrical shells in the assembled state. Therefore all that is required to establish earth contact in the plug-and-socket connection is to establish a metallic connection in the plug between the cable screening and the part-cylindrical shell and to metallically connect, in the associated socket or coupling, the part-cylindrical shell located here to the earth of the device accommodating the socket or to the cable screening adjoining the coupling, as has been standard practice until now where such plugs and sockets or couplings are concerned. 
     When using the invention in plugs with a metal plug housing which encloses the part-cylindrical shells and is only separated from these by a narrow gap, a slight expansion of the part-cylindrical shells complementing one another to form a complete cylinder is achieved in the assembled state via the contact spring element. The individual part-cylindrical shells are thereby pushed outwards slightly, so that they establish electrical contact with the cylindrical inner surface of the metal plug housing by way of their outer surface. The earth connection between the plug and socket or coupling is improved further as a result. 
     As the plug housing is no longer needed for earth contact in the plug-and-socket connection according to the invention, it may consist completely of non-conducting plastics material. A plug-and-socket connection according to the invention can be assembled at a very low cost from a few individual parts while still guaranteeing effective and reliable earth contact connection in the assembled state. The contact spring elements establishing the cross-contact between the part-cylindrical shells may be produced in different ways at the longitudinal edge. In the case of small to medium-sized plugs whose part-cylindrical shells consist of thin spring plate, the contact spring element may be produced by a single longitudinal slot extending parallel to the longitudinal edge or by a plurality of short longitudinal slots formed one behind the other in the spring plate shell, with the narrow spring plate web or spring plate webs thereby formed and connected to the shell on one or both sides being bent outwards slightly. In the case of larger plugs whose part-cylindrical shells have thicker walls, the contact spring elements may consist of repeatedly folded plate webs which are worked out of the part-cylindrical shells via slots, or contact spring parts, which are optionally separate, may be inserted in corresponding edge recesses in the part-cylindrical shells. 
     The contact springs are distributed over the part-cylindrical shells such that no torsional forces are exerted on the part-cylindrical shells used for position location when assembly takes place. With regard to a multipole plug-and-socket connection with semicylindrical shells provided at the plug or socket/coupling, as are most common in practice, contact spring elements are only provided at one of the semicylindrical shells, preferably at that of the plug, this being at both longitudinal edges. This prevents the semicylindrical shells, which complement one another to form a complete cylinder, from turning in one direction upon assembly and then losing the predetermined orientation between the plug pins and the female contacts and therefore no longer guaranteeing the object of exact position location during assembly. 
     As the mechanical construction provided for position location is maintained in the invention, a plug additionally equipped according to the invention with contact springs is entirely compatible with sockets or plug couplings commonly used until now. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is illustrated in detail in the following on the basis of an embodiment and with reference to diagrammatic drawings. 
     FIG. 1 shows a multipole plug-and-socket connection when pulled apart, consisting of a plug and an associated socket, 
     FIG. 2 shows in detail the semicylindrical shells according to the invention which are used in this case, 
     FIGS. 3 and 4 show further embodiments for the formation of the contact spring elements. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The plug which is represented in FIG. 1 consists of an insulating material body  2  which accommodates the contact pins  1  and over which a metal semicylindrical shell  3  is placed. This construction unit is inserted in a metal cylindrical plug housing  5 . In the mounted state the front edge of the semicylindrical shell  3  extends almost to the edge of the plug housing  5 . The insulating material body  2  with the semicylindrical shell  3  attached thereto is held in the plug housing  5  by a soldered window sleeve  6 , which is pushed inwards by a collet  7  and a clamping nut  8 , which is screwed onto the plug housing  5 . The connecting cable, which is not shown, is introduced into the plug housing interior through the clamping nut  8  and the collet  7 , and the cable screening, which consists of metal braiding, is placed over the conical surface  9  of the collet and clamped between this conical surface  9  and the conical surface  10  of the soldered window sleeve  6  in the assembled state. The other end  11  of the soldered window sleeve  6  presses onto the collar  12  of the semicylindrical shell  3  in the clamped state. There is thus direct metallic contact between the cable screening and the semicylindrical shell  3 . 
     A cylindrical insulating material body with the associated female contacts  21 , being disposed in a metal cylindrical socket housing  20 , is inserted in the associated socket, which may also be formed as a coupling, represented in the illustrated embodiment, and a metal semicylindrical shell  23  is again attached to the insulating material body as it is to the body  2 . If the socket is formed as a coupling, a coupling housing corresponding to the plug housing  5  is provided and the screening of the cable which is attached to the coupling is again metallically connected to the semishell  23  as in the case of the plug. 
     FIG. 2 is a scaled-up illustration of the co-operation of the two semicylindrical shells  3  and  23 , which guarantee exact positioning of the plug pins  1  in relation to the female contacts  21 . The plug and socket or coupling can only be assembled when the two semicylindrical shells are in the position represented in FIGS. 1 and 2, and the predetermined association of the plug pins and female contacts only occurs in this position. 
     According to the invention at least one contact spring element is formed at least at one of the longitudinal edges of at least one of the semicylindrical shells  3  and  23 . In the illustrated embodiment the semicylindrical shell  3  of the plug consists of spring plate, and a contact spring  13  is in each case formed at both of its longitudinal edges  22 , which spring is arched outwards slightly and establishes contact with the longitudinal edges  22  of the semicylindrical shell  23  of the socket in the assembled state. In the embodiment according to FIGS. 1 and 2 this contact spring  13  is formed by a longitudinal slot  14  which extends parallel to the longitudinal edge  22 , the resulting narrow web  15 , which is connected at both ends to the semicylindrical shell  3 ,. is arched outwards slightly and forms the contact spring  13 . The longitudinal slot  14  could also be open at one end, preferably at the end facing the collar  12 , so as to produce a contact spring which is only attached to the semishell  3  on one side, in which case, however, steps must be taken to ensure that the spring does not hook onto the mating piece when the plug-and-socket connection is disengaged. A plurality of short spring elements which are either closed or open on one side could also be formed one behind the other along the longitudinal edges  22  according to the same principle. In order to achieve a completely HF-tight screening for some applications, the longitudinal slot  14  or the plurality of successive longitudinal slots could also be filled with or covered (bridged) by a flexible conductive material  35  such as an inserted metal foil material or a conductive elastic silicone material. 
     This additional contact spring  13  at the edge of the semishells establishes effective electrical contact between the longitudinal edges  22  of the semicylindrical shells  3  and  23  and thus effective and defined earth contact between the cable screening and the housing accommodating the socket or the cable screening of a coupling in the assembled state. The plug housing  5  does not need to be formed from metal, it could consist completely of a plastics material. However if a metal plug housing is provided for other reasons, the measure according to the invention has the additional advantage of the two semicylindrical shells  3  and  23  being expanded slightly in the radial direction by the contact springs  13  and additional earth contact thereby being established between the cylindrical inside of the metal housing  5  and the outside of the semicylindrical shells  3  and  23 . 
     FIG. 3 shows a further embodiment for the formation of the contact spring element  13 , which again is formed by a slot  14  in the semicylindrical shell  3  of the plug. The slot  14  is open at the front, thereby producing a plate web  16  which is only located on one side of the semicylindrical shell  3  and whose end which leads in the plug-in direction is widened to form a contact  18 . However this type of contact spring element is only suitable for plug-and-socket connections in which the plate web, which protrudes freely forwards, does not impair the position location process when assembling the plug and socket/coupling. In this respect it is of greater advantage to form the contact spring element  13  according to FIG. 4, as in this case the open slot faces the rear in the plug-in direction  19 , i.e. the collar  12 , so that the plate web cannot become hooked. Increased spring force is achieved in the embodiment according to FIG. 4 by working a repeatedly folded plate web  32  out of the semicylindrical shell  3  via U-shaped slots  30 ,  31 , which web, although being connected at both ends to the semicylindrical shell  3 , nevertheless acts as a spring element which is only attached to the semicylindrical shell  3  on one side. 
     The measure according to the invention can be used with a wide variety of multipole plug-and-socket connectors of any desired size, also with mixed-component plug-and-socket connectors having coaxial cables, light guides, thermocouples, etc. (Fischer Catalogue, Sections E to G).