Abstract:
The invention relates to a shielded connector for a motor vehicle. The connector comprises at least one casing shielding element. The shielding element includes a cable outlet portion provided with a plurality of resilient tabs that are integral with the shielding element. The tabs include a contact zone in electrical contact with a ferrule crimped to a shielding braid of a cable. The contact zone is maintained pressed against the shielding braid by means of a removable clamping ring.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a national stage application under 35 U.S.C. §371 of PCT Application Number PCT/EP2015/062970 having an international filing date of Jun. 10, 2015, which designated the United States, said PCT application claiming the benefit of priority under Article 8 of the Patent Cooperation Treaty to French Patent Application No. 1455366, now French Patent No. 3022410, having a filing date of Jun. 12, 2014, the entire disclosure of each of which are hereby incorporated herein by reference. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The invention relates to the field of electromagnetically shielded electrical connectors. In many applications, and in particular for example in the field of electrical power connectors for rechargeable electric or hybrid motor vehicles, the cables and electrical connections must be electromagnetically shielded. 
       BACKGROUND OF THE INVENTION 
       [0003]    In effect, due to the electrical powers involved in these applications, the shielding of the cables and connectors is essential in order to avoid interferences. It is thus important to assure continued shielding in the cable bundles involved in these applications and in particular at the connectors present in these bundles. 
         [0004]    Various solutions have been developed for this purpose. As described for example in document WO 2011/124562 A1, a shielded connector for a motor vehicle has been designed which comprises an electrically insulating inner casing with at least one cavity accommodating a contact electrically connected to an electrical cable provided with a shielding braid. At least one casing shielding element, which is electrically conductive and which has a cable outlet portion, is placed at least partially around the casing interior. This type of connector, although capable of satisfying the technical requirements, can be difficult to repair. 
         [0005]    Thus, such connectors must be produced in an effective way and at a lower cost whilst satisfying demanding quality standards and allowing any potential repairs of the cable. 
         [0006]    The quality of the electrical connection between the shielding braid of a cable and the shielding element of the casing of the connector mounted thereon, as well as the robustness of the cable outlet portion of this shielding element are particularly critical in this regard. In fact, the cable at the connector outlet can be subjected to strong stresses and vibrations. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The object of the invention is to produce a shielded connector that at least partially satisfies the above-mentioned demands. 
         [0008]    This objective is achieved by a connector of the above-indicated type, in which at least one resilient tab has a contact zone kept pressed against the shielding braid by means of a removable clamping ring (the term “removable” in this document being relative to the position on the tab(s)—in other words, the clamping ring can be removed from its position in which it at least partially covers the tab(s), but cannot be removed completely or easily from the cable). 
         [0009]    Thus, the elasticity of the tab can accommodate the movements of the cable at the connector outlet whilst avoiding mechanical breakage of the casing shielding element and interruption of the electrical continuity between the casing shielding element and the shielding braid. This arrangement makes the connection between the casing shielding element and the cable flexible, thus freeing the casing shielding element of excessive stresses. 
         [0010]    In addition, the clamping ring makes it possible to hold the resilient tab in contact with the shielding braid. The fact that the clamping ring is also removable makes it easily possible to release the connection between the casing shielding element and the shielding braid, thus providing the possibility of repairing just the cable more easily, without having to replace other elements of the connector. 
         [0011]    This connector can comprise any of the following features, considered individually or in combination:
       it comprises a seal around the cable and in contact with the clamping ring; in this case, the clamping ring forms a stop or surface, against which the seal can be compressed;   it comprises an outer ferrule crimped to the shielding braid and against which the resilient tab is pressed by the clamping ring; in this case, the electrical connection between the shielding element and the shielding braid is reinforced by the fact that the tab is in contact with a rigid element;   it comprises an inner ferrule placed around the shielding braid and over which the shielding braid is folded; this arrangement makes it possible to secure the crimping of the outer ferrule and to ensure an improved holding of the outer ferrule on the cable as well as an optimized electrical connection between the shielding braid and the rigid ferrules between which said braid is sandwiched.       
 
         [0015]    In accordance with another aspect, the invention relates to a method for assembling a shielded connector for motor vehicles, comprising the following steps:
       providing an electrical cable provided with a shielding braid,   stripping a portion of the shielding braid in the proximity of one of the ends of the electrical cable,   fixing at least one contact at the end of the electrical cable located in the vicinity of the stripped portion of the shielding braid,   inserting the contact into an electrically insulating inner casing, and   placing at least one casing shielding element, which is electrically conductive, on the inner casing, this shielding element comprising a cable outlet portion.       
 
         [0021]    The cable outlet portion is provided with at least one resilient tab integral with the shielding element, which tab extends in line with the portion of the stripped shielding braid. A removable clamping ring can then be returned over the tab, above the portion of the stripped shielding braid. 
         [0022]    This method makes it possible to prepare the cable and the elements which make it possible to ensure the continuity of shielding in the connector solely on the cable. There are no elements involved with the shielding function that are to be assembled in the rest of the connector. 
         [0023]    This method may also include any of the following features, considered individually or in combination:
       an outer ferrule is crimped to the cable at the portion of the stripped shielding braid, and the clamping ring presses the tab against the outer ferrule,   an inner ferrule is placed on the cable, over the portion of the stripped shielding braid, then the shielding braid is folded back over the inner ferrule, before the outer ferrule is crimped to the inner ferrule,   a seal is placed around the cable and against the clamping ring.       
 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0027]    Further features and advantages of the invention will become clear upon reading the following detailed description and studying the accompanying drawings, in which: 
           [0028]      FIG. 1  schematically shows a perspective exploded view of an embodiment of a connector according to the invention; 
           [0029]      FIG. 2  schematically shows a perspective view of the shielding of the connector of  FIG. 1 ; 
           [0030]      FIG. 3  schematically shows, in a perspective and sectional view, a detail of the connection between a shielding element of the connector and the shielding braid of the cable; 
           [0031]      FIGS. 4A and 4B  schematically show, for two different ferrule diameters, the crimping of the outer ferrule at the stripped end of the cable; and 
           [0032]      FIGS. 5A to 5G  show a sequence of steps of the assembly method according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]      FIG. 1  illustrates a non-limiting example of an embodiment of the connector  1 . In accordance with this example, the connector  1  includes an interfacial coupling  2  and a wired coupling  4 , both made of an elastomer material, an inner casing  6 , an outer casing  8 , a device  10  for holding the interfacial coupling  2 , two compression half-shells  12 , a cover  14 , a device  16  for assuring the connection (“CPA” or Connection Positioning Assurance), a secondary locking device  18 , and a spacer  20 , all molded from an electrically insulating plastics material. The connector  1  also includes an inner ferrule  22 , an outer ferrule  24 , and casing shielding elements  26 , all made of metal. 
         [0034]    The connector  1  further includes contacts  28  electrically connected to a cable  30  (see  FIG. 5D ). 
         [0035]      FIG. 2  shows more particularly how the inner ferrule  22  and outer ferrule  24  are arranged with the casing shielding elements  26 . The casing shielding elements  26 , of which there are two in accordance with this example, are produced for example by stamping and cutting from a metal sheet. They are nested with one another to form a cage extending along a longitudinal axis A, between an open end  32  toward the connection interface and an opposite end comprising a cable outlet portion  34 . 
         [0036]    This cable outlet portion  34  has a substantially tubular form, which is symmetrical about the longitudinal axis A. It comprises a plurality of tabs  36  or resilient blades integral with the casing shielding elements  26 . For example, there are ten of these tabs  36  distributed uniformly about the longitudinal axis A. However, it should be noted that the tabs rest on an outer ferrule  24  without any crimping operation having been performed at the casing shielding elements  26  at the cable outlet portion  34 . This thus substantially limits the level of stress exerted on the casing shielding elements  26 . This is also allows manual assembly and facilitates repair operations. 
         [0037]    As has been shown in greater detail in  FIG. 3 , each tab  36  has a curved form. In other words, each tab  36  becomes distanced progressively from the longitudinal axis A as it extends from the casing shielding element  26  to which it is connected, as far as a peak  38 . Then, proceeding from this peak  38 , in the direction of its free end  40 , the tab moves closer toward the longitudinal axis again. The diameter of the circle described at the free ends of the tabs  36 , when these are not stressed, is smaller than the outer diameter of the outer ferrule  24 . Thus, the free ends  40  of the tabs  36  form contact zones which rest on and exert a contact force onto the outer surface  42  of the outer ferrule  24 , when this is housed in the cable outlet portion  34 . 
         [0038]    The inner ferrule  22  has an outer diameter smaller than the inner diameter of the outer ferrule  24 . Thus, the inner ferrule  22  is placed against the cable  30 , above a stripped portion  48  of the shielding braid  44 . The shielding braid  44  is thus in contact with the inner face  46  of the inner ferrule  22 . The shielding braid  44  is also folded over, i.e. turned back on itself, so as to be in contact with the outer surface  50  of the inner ferrule  22 . The outer ferrule  24  is threaded on above the stripped portion  48  of the shielding braid  44  resting on the inner ferrule  22 , against which it is crimped. The outer surface  42  of the outer ferrule  24  is essentially smooth (with no shielding braid visible). Thus, the free ends  40  of the tabs  36  come to rest on this smooth surface and produce reliable and long-lasting electrical contact, even if these free ends  40  start to rub against this outer surface  42  of the outer ferrule  24  during the service life of the connector  1 . 
         [0039]    As shown in  FIG. 4 , the configuration of the resilient tabs  36  presented above makes it possible to accommodate a number of diameters of cables  30 , with a limited number of ferrules of different diameters. For example, in  FIG. 4A , an inner ferrule  22  of large diameter (for example 10.1 mm inner diameter and 10.9 mm outer diameter) can be used for a cable of relatively large diameter, and the crimping teeth  52  extending between the outer ferrule  24  (for example 12.3 mm inner diameter and 13.1 mm outer diameter) and the inner ferrule  22  have a relatively small dimension d (for example d=0.7 mm). As shown in  FIG. 4B , an inner ferrule  22  of small diameter (for example 8.6 mm inner diameter and 9.4 mm outer diameter) can be used for a cable having a relatively small diameter, whilst keeping the same outer ferrule  24  as for the case illustrated in  FIG. 4A . By contrast, in this case, the crimping teeth  52  extending between the outer ferrule  24  and the inner ferrule  22  have a larger dimension D (D=1.45 mm). It should therefore be noted that when the outer diameter of the cable  30  varies, it is sufficient to adapt the diameter of the inner ferrule  22  without changing the diameter (before crimping) of the outer ferrule  24 . 
         [0040]    As shown in  FIG. 1 , the spacer  20  has an inner tubular surface  54  forming a clamping ring  56 . The spacer  20  (and therefore its clamping ring  56 ) is movable along the cable  30  and can be positioned removably above the tabs  36  ( FIG. 5G ). The inner surface  54  of the clamping ring  56 , by pressing against the peak  38  of the tabs  36 , exerts a force which presses and holds the free ends  40  of the tabs  36  in contact with the outer surface  42  of the outer ferrule  24 . In other words, the clamping ring  56  exerts a force on the resilient tab  36 , primarily at the peak  38  thereof, radially, in the direction of the cable  30 . Because the tabs  36  are on the one hand inclined relative to the outer surface  42  of the outer ferrule  24  and on the other hand are resilient, the clamping ring  56  (of which the inner diameter is slightly greater than the outer diameter of the outer ferrule, but smaller than the diameter described at the peaks  38  of the tabs  36 ) can be displaced relatively easily along the cable  30 , then over the tabs  36 . 
         [0041]    In accordance with a variant, the clamping ring  56  and the spacer are two separate elements. 
         [0042]      FIG. 5  illustrates, in greater detail, the assembly of the connector  1  comprising the connection between the casing shielding elements  26  and the shielding braid  44 . Thus, in  FIG. 5A , the cover  14 , the wired coupling  4 , the spacer  20 , and the inner ferrule  22  and outer ferrule  24  have been threaded onto the cable  30  (the two compression half-shells  12  can be placed on the cable  30  subsequently). It should be noted that the inner ferrule  22  and outer ferrule  24  can assume any angular position around the cable  30 , which simplifies the method for assembling the connector according to the invention. 
         [0043]    It can be seen that the clamping ring  56  and the spacer  20  on which the clamping ring is mounted contribute to forming a stop or surface against which the wired coupling  4  can be compressed by the two compression half-shells  12  and the cover  14 . As shown in  FIG. 5B , a portion of the inner insulation of the cable  30  is then removed in the proximity of one of its ends so as to free the wires  58  of the cable  30 . A portion of the outer insulation  60  of the cable  30  is also removed so as to strip the shielding braid  44 , which is then folded over on the inner ferrule  22 . The outer ferrule  24  can then be returned and crimped to the portion of the shielding braid folded over the inner ferrule  22  ( FIG. 5C ). Contacts  28  are then crimped to the ends, previously cleared and stripped, of the wires  58  of the cable  30  ( FIG. 5D ). These contacts  28  are inserted into the inner casing  6  ( FIG. 5E ). The two casing shielding elements  26  are returned to the inner casing  6  ( FIG. 5F ). The tabs  36  cover the outer ferrule  24 . The flexibility of the tabs makes it possible to optimize the performance under vibration without affecting the shielding performance. For example, vibration levels of 42 G sine can be reached, that is to say substantially 17 G RMS, instead of 25 G sine of the existing shielded connectors of this type. It should be noted that the casing shielding elements  26  and their tabs  36  are not crimped to the outer ferrule, which makes disassembly and repair operations possible. The two casing shielding elements  26  are nested one inside the other, and the clamping ring  56  of the spacer  20  is returned to the tabs  36  ( FIG. 5G ). 
         [0044]    The end of the cable  30  thus prepared and shielded can potentially be stored and/or transported before being introduced into the outer casing  8  and assembled with the other elements of the connector  1 .