Patent Publication Number: US-11652316-B2

Title: Retention clip for a mechanical strain relief of a cable

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119 to EP Patent Application No. 20185341.3, filed Jul. 10, 2020, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present disclosure relates to cable connectors, and more particularly, to a retention clip for mechanical strain relief of a cable in a connector. 
     BACKGROUND 
     Cables are often installed between spaced-apart technical units in order to transfer power and/or signals therebetween. In the field of electrical engineering, for example, a conductive core of an electrical cable is electrically connected with conductive counterparts of electrical units, respectively. These electrical connections may be achieved in a separable manner using electrical connectors. Furthermore, permanent joining techniques such as crimping, clamping, soldering, and/or welding may also be involved in these electrical connections. 
     As electrical connections are mainly designed with a focus on their electrical performance, they often exhibit poor mechanical stability. As a result, mechanical strain relief structures are commonly utilized, which receive and divert mechanical loads acting on the electrical cable. The mechanical strain relief structures may thus help to avoid an unwanted pull-out of the electrical cable from the electrical connector or prevent damage at the permanent joinings, for example, due to improper handling of the electrical cable. 
     Existing strain relief structures usually comprise a multitude of separate components, such as clamps and screws, and/or require a time-consuming installation process. In addition, many existing strain relief structures are installed by clamping the electrical cable with excessive force in order to fixate the electrical cable to the electrical connector or electrical unit, respectively. This poses an inherent threat to the cable&#39;s integrity. Furthermore, the electrical cable often tends to slip within many existing strain relief structures when twisted. 
     Therefore, it is desirable for a mechanical strain relief structure to have a low number of components, be easily and quickly installable, while protecting the electrical cable against twisting without causing unnecessary damage to the electrical cable. 
     SUMMARY 
     According to an embodiment of the present disclosure, a retention clip providing mechanical strain relief of a cable in a connector comprises two curved spring sections, each having a free end including at least one discontinuity in a direction along its length, and a base. The two curved spring sections are separated from each other at their respective free ends by a cable insertion gap. A center section of the retention cable extends from the base of one of the two curved spring sections to the base of the other one of the two curved spring sections and includes a cable insertion opening. The cable insertion gap and the cable insertion opening are aligned providing a through-opening extending through the retention clip in a cable insertion direction. Each one of the free ends further defines at least one discontinuity in a direction along its edge. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of example with reference to the accompanying Figures, of which: 
         FIG.  1    is a schematic illustration of a perspective view of a retention clip according to one embodiment of the present disclosure; 
         FIG.  2    is a schematic illustration of another perspective view of the retention clip according to the embodiment shown in  FIG.  1   ; 
         FIG.  3    is a schematic illustration of a top view of a cable assembly according to one embodiment of the present disclosure; 
         FIG.  4    is a schematic illustration of a sectional view of a connector according to one embodiment of the present disclosure; and 
         FIG.  5    is a schematic illustration of another sectional view of a connector according to one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Exemplary embodiments of the present disclosure will be described hereinafter in detail with reference to the attached drawings, wherein the like reference numerals refer to the like elements. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein; rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those skilled in the art. 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     In the following, the structure of possible embodiments of a retention clip  1 , a cable assembly  2  and a connector  4  according to the present invention is explained with reference to the exemplary embodiments shown in  FIGS.  1  to  5   . 
       FIG.  1    shows a perspective view of the retention clip  1  according to one possible embodiment of the present disclosure. The retention clip  1  may be a stamped and bent piece made of stainless steel. Alternatively, the retention clip  1  may be made of a material with a yield strength of at least 930 MPa. As shown, the retention clip  1  comprises two curved spring sections  6  and a center section  8 . Each of the two curved spring sections  6  has a free end  10  and a base  12 . The two curved spring sections  6  are separated from each other at their respective free ends  10  by a cable insertion gap  14 . In particular, the free ends  10  of the two curved spring sections  6  may each have an edge  16 . The edges  16  may be arranged opposite to each other with respect to the cable insertion gap  14 . The edges  16  may further be parallel to each other and may also extend parallel to the center section  8 . The center section  8  extends from the base  12  of one of the two curved spring sections  6  to the base  12  of the other one of the two curved spring sections  6 . Consequently, the two curved spring sections  6  may be monolithically connected at their respective bases  12  by the center section  8 . Further, the center section  8  comprises a cable insertion opening  18 . 
     As shown in  FIGS.  1 - 3   , the cable insertion gap  14  and the cable insertion opening  18  are aligned and provide a through-opening  20  extending through the retention clip  1  in a cable insertion direction  22 . As will be described further herein, a cable  24 , such as an electrical cable  26 , may be passed through the through-opening  20  to be gripped by the retention clip  1 . In particular, a cable jacket surface  28  of the cable  24  abuts against the edges  16  of the free ends  10 . 
     As shown in  FIGS.  1  and  2   , each of the free ends  10  has at least one discontinuity  30  in a direction  32  along its respective edge  16 . The at least one discontinuity  30  of at least one free end  10  may comprise at least one of a recess  34  or a protrusion. In the exemplary embodiment of  FIG.  1   , both free ends  10  have the at least one discontinuity  30  comprising one recess  34 . The recess  34  is a concave cut-out  36  extending from the edge  16  of the corresponding free end  10  into the corresponding curved spring section  6 . The recess  34  has a round shape, more specifically a semi-circular shape. Alternatively, the recess may also be an indentation and/or have an oval shape (not shown). 
     As shown in  FIG.  1   , the recess  34  creates two juxtaposed, mirror-inverted shoulders  38   a,    38   b  on the corresponding free end  10 . A break  40  in the edge  16  of the corresponding free end  10  is formed between the shoulders  38   a,    38   b.  When the cable  24  is gripped by the retention clip  1 , the cable jacket  42  may be locally deformed such that material of the cable jacket  42  enters the recess  34 . Thereby a form fit between the cable jacket  42  and the two shoulders  38   a ,  38   b  may be created. As a result, the transfer of torsional forces oriented in the circumferential direction of the cable are improved, and relative rotational movement between the cable and retention clip impeded. 
     A depth  44  of the respective recess  34  measured perpendicularly to the corresponding edge  16  is preferably smaller than a material thickness  46  of the cable jacket  42  (see  FIG.  3   ). A width  48  of the respective recess  34  measured parallel to the corresponding edge  16  is preferably smaller than an outer diameter  50  of the cable jacket  42  (see  FIG.  3   ). Further, each recess  34  may preferably have its depth  44  and/or width  48  larger than the material thickness  52  of the corresponding free end  10 . 
     The discontinuities  30  of both free ends  10  may be arranged opposite to each other, preferably diametrically opposite to each other. In other words, for each discontinuity  30  of one free end  10 , there may be a counterpart discontinuity  54  arranged at a diametrically opposite position of the respective other free end  10 . This opposite arrangement may be done with respect to the cable insertion gap  14  and/or with respect to a center line  56  of the cable insertion opening  18 . This is also shown in  FIG.  1   . 
     The at least one discontinuity  30  of at least one free end  10  may be positioned in the middle of the edge  16  of the corresponding free end  10 . Further, the at least one discontinuity  30  of at least one free end  10  may overlap with the cable insertion opening  18  in the cable insertion direction  22 . In the shown exemplary embodiment of  FIG.  1   , the at least one discontinuity  30  of each free end  10  is positioned in the middle of the corresponding edge  16  and overlaps with the cable insertion opening  18 , respectively. In particular, each recess  34  is aligned with the cable insertion opening  18  in the cable insertion direction  22  and arranged in the middle of the respective edge  16 . 
     Additionally or alternatively, the at least one discontinuity  30  of at least one free end  10  may comprise a protrusion. In particular, the protrusion may be convex and project from the edge  16  of the corresponding free end  10  towards the edge  16  of the respectively opposite free end  10 . The retention clip  1  may be symmetrical with respect to a plane  58  extending perpendicularly to the center section  8  (see  FIG.  5   ). 
     The perspective view of the retention clip  1  of  FIG.  2    shows that the free ends  10  of the curved spring sections  6  may be angled towards the center section  8  and partly cover the cable insertion opening  18  in the cable insertion direction  22 . In particular, the free ends  10  of the curved spring sections  6  may form lead-in chamfers  60  towards the cable insertion opening  18 . 
     As can be seen in  FIGS.  1  and  2   , the curved spring sections  6  may extend away from the cable insertion opening  18  at their respective bases  12  and may be curled back towards the cable insertion opening  18 , such that their respective free ends  10  generally point towards the cable insertion opening  18 . The free ends  10  may further be spaced apart from the center section  8  in the cable insertion direction  22 , increasing an available range of motion of the free ends. 
     In particular, the two curved spring sections  6  may be formed by flexible spring fingers  62  extending in a curved manner between the respective free end  10  and base  12 . The spring fingers  62  may exhibit multiple, preferably mutually parallel, slits  64  extending through the spring fingers  62  in the direction of their curvature. The curvature may be continuous and have a degree of curvature equal to or larger than 180°. The respective free ends  10  of the curved spring sections  6 , may be formed by substantially straight sections  66  of the spring fingers  62 , which transition into said curvature. 
       FIG.  2    shows that the free ends  10  of the curved spring sections  6  may have rounded edges  68 . A rounding  70  of each rounded edge  68  may extend in a circumferential direction  72  with respect to the direction  32  along the respective edge  16 . In particular, the rounded edges  68  may be formed by bending an outer section  74  of the free ends  10  i.e., the straight sections  66 , inwardly or outwardly. The bending of the free ends  10  may result in the free ends  10  having two layers of material at their respective outer sections  74 . Preferably, corners  76   a,    76   b  of the shoulders  38   a,    38   b  are sharper than the roundings  70  of the rounded edges  68  (see  FIG.  1   ). 
     According to another embodiment, the free ends may have two or more discontinuities. For example, multiple recesses and/or protrusions may be formed on the edges of the free ends resulting in a waved or riffled edge, respectively. In this case, the waves or riffles are aligned along the direction of the corresponding edge. 
     As is further shown in  FIG.  2   , the center section  8  may be formed by a perforated sheet section  78  having the cable insertion opening  18  in the center  80  of the sheet section  78 , such that the sheet section  78  forms a frame  82  around the cable insertion opening  18 . The sheet section  78  of the shown exemplary embodiment is rectangular, preferably square. Furthermore, the sheet section  78  may be flat and straight. 
     The flexible spring fingers  62  may extend from two opposite rims  84  of the perforated sheet section  78 , while the straight sections  66  of the flexible spring fingers  62 , corresponding to the edges  16  of the free ends  10 , at least partially overlap with the cable insertion opening  18  in the cable insertion direction  22 . Thereby, the cable insertion opening  18  may have a larger clear width than the cable insertion gap  14 . In particular, a distance  86  between the opposite edges  16  of the free ends  10  may be shorter than a diameter  88  of the cable insertion opening  18 . 
     Optionally, the retention clip  1  may comprise two guiding flaps  90 , which protrude from the center section  8  towards the cable insertion gap  14 . As shown in  FIG.  1   , the guiding flaps  90  preferably protrude from a circumference  92  of the cable insertion opening  18  on two opposite sides thereof. The guiding flaps  90  extend obliquely away from a center axis  94  of the through-opening  20  provided by the cable insertion gap  14  and the cable insertion opening  18 . In particular, the guiding flaps  90  may be formed by cantilever tabs  96  having their supported ends  98  bent towards the cable insertion gap  14  and their unsupported ends  100  arranged opposite to each other with respect to the cable insertion gap  14  (see  FIG.  2   ). A distance  102  between the unsupported ends  100  of the guiding flaps  90  may be larger than a distance  104  between the supported ends  98  of the guiding flaps  90 , resulting in a lead-in chamfer  106  (see  FIG.  4   ). 
       FIG.  3    shows a top view of the cable assembly  2 , comprising the retention clip  1  according to any one of the embodiments described above and a cable  24  that is passed in the cable insertion direction  22  through the cable insertion gap  14  and the cable insertion opening  18  of the retention clip  1 . In the shown exemplary embodiment, the cable  24  is an electrical cable  26  comprising a conductive core  110  circumferentially surrounded by a cable jacket  42 . Alternatively, the cable  24  may also be an optical cable or a cable comprising means for transmitting both electrical and optical signals and/or power. 
     The free ends  10  of the curved spring sections  6  are elastically pressed against an outer surface  112  of the cable  24  e.g., a cable jacket surface  28 . The at least one discontinuity  30  of each free end  10  abuts against the outer surface  112  of the cable  24 . Preferably, the free ends  10  of the curved spring sections  6  are outwardly defected by the cable jacket surface  28 . Further, the free ends  10  are angled with respect to the outer surface  112  of the cable  24  and point towards the cable insertion opening  18 . Preferably, each free end  10  is inclined by an angle  116  relative to the cable insertion direction  22 . Advantageously, the angle  116  may for example amount to 30° to 40°. Thereby, the cable  24  is gripped between the edges  16  of the free ends  10  in a self-locking manner. The necessary angle  116  for achieving a self-lock may vary depending on the outer diameter  50  of the cable jacket  42 , the material of the cable jacket  42 , the material of the retention clip  1  and/or any other substance present between the cable jacket  42  and the retention clip  1 , such as a sealing gel. 
     As also shown in  FIG.  3   , the guiding flaps  90  protrude on the same face  118  of the center section  8  as the two curved spring sections  6 . In particular, the guiding flaps  90  may extend from between the bases  12  of the curved spring sections  6  towards and beyond the free ends  10  of the curved spring sections  6 . 
       FIGS.  4  and  5    show the connector  4  in a sectional view. The connector  4  comprises a retention clip  1  according to any one of the embodiments described above and a connector housing  120 . The connector housing  120  has a reception chamber  122  and a cable insertion aperture  124  for feeding a cable  24  into the reception chamber  122 , wherein the retention clip  1  is integrated in the reception chamber  122 , the cable insertion opening  18  of the retention clip  1  being aligned with the cable insertion aperture  124  of the connector housing  120 . Further, the cable insertion gap  14  of the retention clip  1  is arranged between the cable insertion aperture  124  and the cable insertion opening  18 . 
     As can be seen in  FIG.  5   , inner walls  126  of the reception chamber  122  may be shaped complementarily to the curved spring sections  6  of the retention clip  1 . In particular, the retention clip  1  fits snugly into the reception chamber  122 . Preferably, the curved spring sections  6  of the retention clip  1  abut along their entire curvature against the inner walls  126  of the retention chamber  122 . 
     The connector housing  120  may comprise two mateable housing halves  128   a,    128   b , which jointly form the connector housing  120  in an assembled state  130  and surround the retention clip  1  entirely, as shown in  FIG.  4   . In particular, the two housing halves  128   a,    128   b  may each comprise at least part of the reception chamber  122  and be assembled by means of a screw connection, latching connection and/or adhesive connection. 
     In a state prior to assembling the two housing halves  128   a,    128   b,  the retention clip  1  can be placed into one part of the reception chamber  122  of one of the housing halves  128   b . Thereafter, the housing halves may be pre-assembled to a state  132  as shown in  FIG.  5   , in which the screw connection, latching connection and/or adhesive connection is not yet established. 
     The connector  4  may further comprise at least one electrically conductive contact element  134  for terminating an electrical cable  26  and contacting a mating contact of a mating connector. Preferably, the at least one contact element  134  is an insulation displacement contact  136 . In the pre-assembled state  132 , the insulation displacement contact  136  and the retention clip  1  are each preferably placed in a different housing half  128   a,    128   b  of the connector housing as shown in  FIG.  5   . 
     In the configuration shown in  FIG.  5   , an unstripped electrical cable  26  can readily be installed to the connector  4 . In particular, an unstripped end  138  of the electrical cable  26  can be passed through the cable insertion aperture  124 , the cable insertion gap  14  and the cable insertion opening  18 . After passing the cable insertion opening  18 , the unstripped end  138  of the electrical cable  26  preferably reaches a position, in which it is aligned with blades  140  of the insulation displacement contact  136  placed in the other one of the two housing halves  128   a,    128   b . Thereupon, the housing halves  128   a,    128   b  are assembled by pressing both housing halves  128   a ,  128   b  together such that the unstripped end  138  of the electrical cable  26  is terminated by the insulation displacement contact  136 . 
     Referring again to  FIG.  1   , the retention clip  1  may comprise multiple barbed hooks  142 , which claw to the inner walls  126  of the reception chamber  122 . In particular, the barbed hooks  142  may be provided in notches  144  formed at the center section  8  of the retention clip  1 . The inner walls  126  of the reception chamber  122  of the connector housing  120  may have spikes or ribs formed thereon, which enter the notches  144  of the center section  8 , when the retention clip  1  is placed into the reception chamber  122 . Thereupon, the barbed hooks  142  claw into the spikes or ribs and secure the retention clip  1  within the reception chamber  122 . 
     Additionally or alternatively, the retention clip  1  may comprise spikes, which are provided with the barbed hooks  142 . The retention clip  1  may also be glued, soldered or welded to the inner walls  126  of the reception chamber  122 . According to another alternative embodiment, the connector housing  120  may be over-molded on the retention clip  1 . In a sealed embodiment of the connector  4 , the reception chamber  122  may be filled with a sealing gel. The sealing gel may entirely surround the retention clip  1  and fill out the cable insertion gap  14  as well as the cable insertion opening  18 . 
     It should be appreciated for those skilled in this art that the above embodiments are intended to be illustrated, and not restrictive. For example, many modifications may be made to the above embodiments by those skilled in this art, and various features described in different embodiments may be freely combined with each other without conflicting in configuration or principle. 
     Although several exemplary embodiments have been shown and described, it would be appreciated by those skilled in the art that various changes or modifications may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents. 
     As used herein, an element recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.